slice.c

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/*
 * slice.c
 * Copyright (C) 2000-2003 Michel Lespinasse <walken@zoy.org>
 * Copyright (C) 2003      Peter Gubanov <peter@elecard.net.ru>
 * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
 *
 * This file is part of mpeg2dec, a free MPEG-2 video stream decoder.
 * See http://libmpeg2.sourceforge.net/ for updates.
 *
 * mpeg2dec is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * mpeg2dec is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "config.h"

#include <inttypes.h>

#include "mpeg2.h"
#include "attributes.h"
#include "mpeg2_internal.h"

extern mpeg2_mc_t mpeg2_mc;
extern void (* mpeg2_idct_copy) (int16_t * block, uint8_t * dest, int stride);
extern void (* mpeg2_idct_add) (int last, int16_t * block,
                                uint8_t * dest, int stride);
extern void (* mpeg2_cpu_state_save) (cpu_state_t * state);
extern void (* mpeg2_cpu_state_restore) (cpu_state_t * state);

#include "vlc.h"

static inline int get_macroblock_modes (mpeg2_decoder_t * const decoder)
{
#define bit_buf (decoder->bitstream_buf)
#define bits (decoder->bitstream_bits)
#define bit_ptr (decoder->bitstream_ptr)
    int macroblock_modes;
    const MBtab * tab;

    switch (decoder->coding_type) {
    case I_TYPE:

        tab = MB_I + UBITS (bit_buf, 1);
        DUMPBITS (bit_buf, bits, tab->len);
        macroblock_modes = tab->modes;

        if ((! (decoder->frame_pred_frame_dct)) &&
            (decoder->picture_structure == FRAME_PICTURE)) {
            macroblock_modes |= UBITS (bit_buf, 1) * DCT_TYPE_INTERLACED;
            DUMPBITS (bit_buf, bits, 1);
        }

        return macroblock_modes;

    case P_TYPE:

        tab = MB_P + UBITS (bit_buf, 5);
        DUMPBITS (bit_buf, bits, tab->len);
        macroblock_modes = tab->modes;

        if (decoder->picture_structure != FRAME_PICTURE) {
            if (macroblock_modes & MACROBLOCK_MOTION_FORWARD) {
                macroblock_modes |= UBITS (bit_buf, 2) << MOTION_TYPE_SHIFT;
                DUMPBITS (bit_buf, bits, 2);
            }
            return macroblock_modes | MACROBLOCK_MOTION_FORWARD;
        } else if (decoder->frame_pred_frame_dct) {
            if (macroblock_modes & MACROBLOCK_MOTION_FORWARD)
                macroblock_modes |= MC_FRAME << MOTION_TYPE_SHIFT;
            return macroblock_modes | MACROBLOCK_MOTION_FORWARD;
        } else {
            if (macroblock_modes & MACROBLOCK_MOTION_FORWARD) {
                macroblock_modes |= UBITS (bit_buf, 2) << MOTION_TYPE_SHIFT;
                DUMPBITS (bit_buf, bits, 2);
            }
            if (macroblock_modes & (MACROBLOCK_INTRA | MACROBLOCK_PATTERN)) {
                macroblock_modes |= UBITS (bit_buf, 1) * DCT_TYPE_INTERLACED;
                DUMPBITS (bit_buf, bits, 1);
            }
            return macroblock_modes | MACROBLOCK_MOTION_FORWARD;
        }

    case B_TYPE:

        tab = MB_B + UBITS (bit_buf, 6);
        DUMPBITS (bit_buf, bits, tab->len);
        macroblock_modes = tab->modes;

        if (decoder->picture_structure != FRAME_PICTURE) {
            if (! (macroblock_modes & MACROBLOCK_INTRA)) {
                macroblock_modes |= UBITS (bit_buf, 2) << MOTION_TYPE_SHIFT;
                DUMPBITS (bit_buf, bits, 2);
            }
            return macroblock_modes;
        } else if (decoder->frame_pred_frame_dct) {
            /* if (! (macroblock_modes & MACROBLOCK_INTRA)) */
            macroblock_modes |= MC_FRAME << MOTION_TYPE_SHIFT;
            return macroblock_modes;
        } else {
            if (macroblock_modes & MACROBLOCK_INTRA)
                goto intra;
            macroblock_modes |= UBITS (bit_buf, 2) << MOTION_TYPE_SHIFT;
            DUMPBITS (bit_buf, bits, 2);
            if (macroblock_modes & (MACROBLOCK_INTRA | MACROBLOCK_PATTERN)) {
            intra:
                macroblock_modes |= UBITS (bit_buf, 1) * DCT_TYPE_INTERLACED;
                DUMPBITS (bit_buf, bits, 1);
            }
            return macroblock_modes;
        }

    case D_TYPE:

        DUMPBITS (bit_buf, bits, 1);
        return MACROBLOCK_INTRA;

    default:
        return 0;
    }
#undef bit_buf
#undef bits
#undef bit_ptr
}

static inline void get_quantizer_scale (mpeg2_decoder_t * const decoder)
{
#define bit_buf (decoder->bitstream_buf)
#define bits (decoder->bitstream_bits)
#define bit_ptr (decoder->bitstream_ptr)

    int quantizer_scale_code;

    quantizer_scale_code = UBITS (bit_buf, 5);
    DUMPBITS (bit_buf, bits, 5);

    decoder->quantizer_matrix[0] =
        decoder->quantizer_prescale[0][quantizer_scale_code];
    decoder->quantizer_matrix[1] =
        decoder->quantizer_prescale[1][quantizer_scale_code];
    decoder->quantizer_matrix[2] =
        decoder->chroma_quantizer[0][quantizer_scale_code];
    decoder->quantizer_matrix[3] =
        decoder->chroma_quantizer[1][quantizer_scale_code];
#undef bit_buf
#undef bits
#undef bit_ptr
}

static inline int get_motion_delta (mpeg2_decoder_t * const decoder,
                                    const int f_code)
{
#define bit_buf (decoder->bitstream_buf)
#define bits (decoder->bitstream_bits)
#define bit_ptr (decoder->bitstream_ptr)

    int delta;
    int sign;
    const MVtab * tab;

    if (bit_buf & 0x80000000) {
        DUMPBITS (bit_buf, bits, 1);
        return 0;
    } else if (bit_buf >= 0x0c000000) {

        tab = MV_4 + UBITS (bit_buf, 4);
        delta = (tab->delta << f_code) + 1;
        bits += tab->len + f_code + 1;
        bit_buf <<= tab->len;

        sign = SBITS (bit_buf, 1);
        bit_buf <<= 1;

        if (f_code)
            delta += UBITS (bit_buf, f_code);
        bit_buf <<= f_code;

        return (delta ^ sign) - sign;

    } else {

        tab = MV_10 + UBITS (bit_buf, 10);
        delta = (tab->delta << f_code) + 1;
        bits += tab->len + 1;
        bit_buf <<= tab->len;

        sign = SBITS (bit_buf, 1);
        bit_buf <<= 1;

        if (f_code) {
            NEEDBITS (bit_buf, bits, bit_ptr);
            delta += UBITS (bit_buf, f_code);
            DUMPBITS (bit_buf, bits, f_code);
        }

        return (delta ^ sign) - sign;

    }
#undef bit_buf
#undef bits
#undef bit_ptr
}

static inline int bound_motion_vector (const int vector, const int f_code)
{
    return ((int32_t)vector << (27 - f_code)) >> (27 - f_code);
}

static inline int get_dmv (mpeg2_decoder_t * const decoder)
{
#define bit_buf (decoder->bitstream_buf)
#define bits (decoder->bitstream_bits)
#define bit_ptr (decoder->bitstream_ptr)

    const DMVtab * tab;

    tab = DMV_2 + UBITS (bit_buf, 2);
    DUMPBITS (bit_buf, bits, tab->len);
    return tab->dmv;
#undef bit_buf
#undef bits
#undef bit_ptr
}

static inline int get_coded_block_pattern (mpeg2_decoder_t * const decoder)
{
#define bit_buf (decoder->bitstream_buf)
#define bits (decoder->bitstream_bits)
#define bit_ptr (decoder->bitstream_ptr)

    const CBPtab * tab;

    NEEDBITS (bit_buf, bits, bit_ptr);

    if (bit_buf >= 0x20000000) {

        tab = CBP_7 + (UBITS (bit_buf, 7) - 16);
        DUMPBITS (bit_buf, bits, tab->len);
        return tab->cbp;

    } else {

        tab = CBP_9 + UBITS (bit_buf, 9);
        DUMPBITS (bit_buf, bits, tab->len);
        return tab->cbp;
    }

#undef bit_buf
#undef bits
#undef bit_ptr
}

static inline int get_luma_dc_dct_diff (mpeg2_decoder_t * const decoder)
{
#define bit_buf (decoder->bitstream_buf)
#define bits (decoder->bitstream_bits)
#define bit_ptr (decoder->bitstream_ptr)
    const DCtab * tab;
    int size;
    int dc_diff;

    if (bit_buf < 0xf8000000) {
        tab = DC_lum_5 + UBITS (bit_buf, 5);
        size = tab->size;
        if (size) {
            bits += tab->len + size;
            bit_buf <<= tab->len;
            dc_diff =
                UBITS (bit_buf, size) - UBITS (SBITS (~bit_buf, 1), size);
            bit_buf <<= size;
            return dc_diff << decoder->intra_dc_precision;
        } else {
            DUMPBITS (bit_buf, bits, 3);
            return 0;
        }
    } else {
        tab = DC_long + (UBITS (bit_buf, 9) - 0x1e0);
        size = tab->size;
        DUMPBITS (bit_buf, bits, tab->len);
        NEEDBITS (bit_buf, bits, bit_ptr);
        dc_diff = UBITS (bit_buf, size) - UBITS (SBITS (~bit_buf, 1), size);
        DUMPBITS (bit_buf, bits, size);
        return dc_diff << decoder->intra_dc_precision;
    }
#undef bit_buf
#undef bits
#undef bit_ptr
}

static inline int get_chroma_dc_dct_diff (mpeg2_decoder_t * const decoder)
{
#define bit_buf (decoder->bitstream_buf)
#define bits (decoder->bitstream_bits)
#define bit_ptr (decoder->bitstream_ptr)
    const DCtab * tab;
    int size;
    int dc_diff;

    if (bit_buf < 0xf8000000) {
        tab = DC_chrom_5 + UBITS (bit_buf, 5);
        size = tab->size;
        if (size) {
            bits += tab->len + size;
            bit_buf <<= tab->len;
            dc_diff =
                UBITS (bit_buf, size) - UBITS (SBITS (~bit_buf, 1), size);
            bit_buf <<= size;
            return dc_diff << decoder->intra_dc_precision;
        } else {
            DUMPBITS (bit_buf, bits, 2);
            return 0;
        }
    } else {
        tab = DC_long + (UBITS (bit_buf, 10) - 0x3e0);
        size = tab->size;
        DUMPBITS (bit_buf, bits, tab->len + 1);
        NEEDBITS (bit_buf, bits, bit_ptr);
        dc_diff = UBITS (bit_buf, size) - UBITS (SBITS (~bit_buf, 1), size);
        DUMPBITS (bit_buf, bits, size);
        return dc_diff << decoder->intra_dc_precision;
    }
#undef bit_buf
#undef bits
#undef bit_ptr
}

#define SATURATE(val)                           \
do {                                            \
    val <<= 4;                                  \
    if (unlikely (val != (int16_t) val))        \
        val = (SBITS (val, 1) ^ 2047) << 4;     \
} while (0)

static void get_intra_block_B14 (mpeg2_decoder_t * const decoder,
                                 const uint16_t * const quant_matrix)
{
    int i;
    int j;
    int val;
    const uint8_t * const scan = decoder->scan;
    int mismatch;
    const DCTtab * tab;
    uint32_t bit_buf;
    int bits;
    const uint8_t * bit_ptr;
    int16_t * const dest = decoder->DCTblock;

    i = 0;
    mismatch = ~dest[0];

    bit_buf = decoder->bitstream_buf;
    bits = decoder->bitstream_bits;
    bit_ptr = decoder->bitstream_ptr;

    NEEDBITS (bit_buf, bits, bit_ptr);

    while (1) {
        if (bit_buf >= 0x28000000) {

            tab = DCT_B14AC_5 + (UBITS (bit_buf, 5) - 5);

            i += tab->run;
            if (i >= 64)
                break;  /* end of block */

        normal_code:
            j = scan[i];
            bit_buf <<= tab->len;
            bits += tab->len + 1;
            val = (tab->level * quant_matrix[j]) >> 4;

            /* if (bitstream_get (1)) val = -val; */
            val = (val ^ SBITS (bit_buf, 1)) - SBITS (bit_buf, 1);

            SATURATE (val);
            dest[j] = val;
            mismatch ^= val;

            bit_buf <<= 1;
            NEEDBITS (bit_buf, bits, bit_ptr);

            continue;

        } else if (bit_buf >= 0x04000000) {

            tab = DCT_B14_8 + (UBITS (bit_buf, 8) - 4);

            i += tab->run;
            if (i < 64)
                goto normal_code;

            /* escape code */

            i += UBITS (bit_buf << 6, 6) - 64;
            if (i >= 64)
                break;  /* illegal, check needed to avoid buffer overflow */

            j = scan[i];

            DUMPBITS (bit_buf, bits, 12);
            NEEDBITS (bit_buf, bits, bit_ptr);
            val = (SBITS (bit_buf, 12) * quant_matrix[j]) / 16;

            SATURATE (val);
            dest[j] = val;
            mismatch ^= val;

            DUMPBITS (bit_buf, bits, 12);
            NEEDBITS (bit_buf, bits, bit_ptr);

            continue;

        } else if (bit_buf >= 0x02000000) {
            tab = DCT_B14_10 + (UBITS (bit_buf, 10) - 8);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else if (bit_buf >= 0x00800000) {
            tab = DCT_13 + (UBITS (bit_buf, 13) - 16);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else if (bit_buf >= 0x00200000) {
            tab = DCT_15 + (UBITS (bit_buf, 15) - 16);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else {
            tab = DCT_16 + UBITS (bit_buf, 16);
            bit_buf <<= 16;
            GETWORD (bit_buf, bits + 16, bit_ptr);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        }
        break;  /* illegal, check needed to avoid buffer overflow */
    }
    dest[63] ^= mismatch & 16;
    DUMPBITS (bit_buf, bits, tab->len); /* dump end of block code */
    decoder->bitstream_buf = bit_buf;
    decoder->bitstream_bits = bits;
    decoder->bitstream_ptr = bit_ptr;
}

static void get_intra_block_B15 (mpeg2_decoder_t * const decoder,
                                 const uint16_t * const quant_matrix)
{
    int i;
    int j;
    int val;
    const uint8_t * const scan = decoder->scan;
    int mismatch;
    const DCTtab * tab;
    uint32_t bit_buf;
    int bits;
    const uint8_t * bit_ptr;
    int16_t * const dest = decoder->DCTblock;

    i = 0;
    mismatch = ~dest[0];

    bit_buf = decoder->bitstream_buf;
    bits = decoder->bitstream_bits;
    bit_ptr = decoder->bitstream_ptr;

    NEEDBITS (bit_buf, bits, bit_ptr);

    while (1) {
        if (bit_buf >= 0x04000000) {

            tab = DCT_B15_8 + (UBITS (bit_buf, 8) - 4);

            i += tab->run;
            if (i < 64) {

            normal_code:
                j = scan[i];
                bit_buf <<= tab->len;
                bits += tab->len + 1;
                val = (tab->level * quant_matrix[j]) >> 4;

                /* if (bitstream_get (1)) val = -val; */
                val = (val ^ SBITS (bit_buf, 1)) - SBITS (bit_buf, 1);

                SATURATE (val);
                dest[j] = val;
                mismatch ^= val;

                bit_buf <<= 1;
                NEEDBITS (bit_buf, bits, bit_ptr);

                continue;

            } else {

                /* end of block. I commented out this code because if we */
                /* dont exit here we will still exit at the later test :) */

                /* if (i >= 128) break; */      /* end of block */

                /* escape code */

                i += UBITS (bit_buf << 6, 6) - 64;
                if (i >= 64)
                    break;      /* illegal, check against buffer overflow */

                j = scan[i];

                DUMPBITS (bit_buf, bits, 12);
                NEEDBITS (bit_buf, bits, bit_ptr);
                val = (SBITS (bit_buf, 12) * quant_matrix[j]) / 16;

                SATURATE (val);
                dest[j] = val;
                mismatch ^= val;

                DUMPBITS (bit_buf, bits, 12);
                NEEDBITS (bit_buf, bits, bit_ptr);

                continue;

            }
        } else if (bit_buf >= 0x02000000) {
            tab = DCT_B15_10 + (UBITS (bit_buf, 10) - 8);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else if (bit_buf >= 0x00800000) {
            tab = DCT_13 + (UBITS (bit_buf, 13) - 16);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else if (bit_buf >= 0x00200000) {
            tab = DCT_15 + (UBITS (bit_buf, 15) - 16);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else {
            tab = DCT_16 + UBITS (bit_buf, 16);
            bit_buf <<= 16;
            GETWORD (bit_buf, bits + 16, bit_ptr);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        }
        break;  /* illegal, check needed to avoid buffer overflow */
    }
    dest[63] ^= mismatch & 16;
    DUMPBITS (bit_buf, bits, tab->len); /* dump end of block code */
    decoder->bitstream_buf = bit_buf;
    decoder->bitstream_bits = bits;
    decoder->bitstream_ptr = bit_ptr;
}

static int get_non_intra_block (mpeg2_decoder_t * const decoder,
                                const uint16_t * const quant_matrix)
{
    int i;
    int j;
    int val;
    const uint8_t * const scan = decoder->scan;
    int mismatch;
    const DCTtab * tab;
    uint32_t bit_buf;
    int bits;
    const uint8_t * bit_ptr;
    int16_t * const dest = decoder->DCTblock;

    i = -1;
    mismatch = -1;

    bit_buf = decoder->bitstream_buf;
    bits = decoder->bitstream_bits;
    bit_ptr = decoder->bitstream_ptr;

    NEEDBITS (bit_buf, bits, bit_ptr);
    if (bit_buf >= 0x28000000) {
        tab = DCT_B14DC_5 + (UBITS (bit_buf, 5) - 5);
        goto entry_1;
    } else
        goto entry_2;

    while (1) {
        if (bit_buf >= 0x28000000) {

            tab = DCT_B14AC_5 + (UBITS (bit_buf, 5) - 5);

        entry_1:
            i += tab->run;
            if (i >= 64)
                break;  /* end of block */

        normal_code:
            j = scan[i];
            bit_buf <<= tab->len;
            bits += tab->len + 1;
            val = ((2 * tab->level + 1) * quant_matrix[j]) >> 5;

            /* if (bitstream_get (1)) val = -val; */
            val = (val ^ SBITS (bit_buf, 1)) - SBITS (bit_buf, 1);

            SATURATE (val);
            dest[j] = val;
            mismatch ^= val;

            bit_buf <<= 1;
            NEEDBITS (bit_buf, bits, bit_ptr);

            continue;

        }

    entry_2:
        if (bit_buf >= 0x04000000) {

            tab = DCT_B14_8 + (UBITS (bit_buf, 8) - 4);

            i += tab->run;
            if (i < 64)
                goto normal_code;

            /* escape code */

            i += UBITS (bit_buf << 6, 6) - 64;
            if (i >= 64)
                break;  /* illegal, check needed to avoid buffer overflow */

            j = scan[i];

            DUMPBITS (bit_buf, bits, 12);
            NEEDBITS (bit_buf, bits, bit_ptr);
            val = 2 * (SBITS (bit_buf, 12) + SBITS (bit_buf, 1)) + 1;
            val = (val * quant_matrix[j]) / 32;

            SATURATE (val);
            dest[j] = val;
            mismatch ^= val;

            DUMPBITS (bit_buf, bits, 12);
            NEEDBITS (bit_buf, bits, bit_ptr);

            continue;

        } else if (bit_buf >= 0x02000000) {
            tab = DCT_B14_10 + (UBITS (bit_buf, 10) - 8);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else if (bit_buf >= 0x00800000) {
            tab = DCT_13 + (UBITS (bit_buf, 13) - 16);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else if (bit_buf >= 0x00200000) {
            tab = DCT_15 + (UBITS (bit_buf, 15) - 16);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else {
            tab = DCT_16 + UBITS (bit_buf, 16);
            bit_buf <<= 16;
            GETWORD (bit_buf, bits + 16, bit_ptr);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        }
        break;  /* illegal, check needed to avoid buffer overflow */
    }
    dest[63] ^= mismatch & 16;
    DUMPBITS (bit_buf, bits, tab->len); /* dump end of block code */
    decoder->bitstream_buf = bit_buf;
    decoder->bitstream_bits = bits;
    decoder->bitstream_ptr = bit_ptr;
    return i;
}

static void get_mpeg1_intra_block (mpeg2_decoder_t * const decoder)
{
    int i;
    int j;
    int val;
    const uint8_t * const scan = decoder->scan;
    const uint16_t * const quant_matrix = decoder->quantizer_matrix[0];
    const DCTtab * tab;
    uint32_t bit_buf;
    int bits;
    const uint8_t * bit_ptr;
    int16_t * const dest = decoder->DCTblock;

    i = 0;

    bit_buf = decoder->bitstream_buf;
    bits = decoder->bitstream_bits;
    bit_ptr = decoder->bitstream_ptr;

    NEEDBITS (bit_buf, bits, bit_ptr);

    while (1) {
        if (bit_buf >= 0x28000000) {

            tab = DCT_B14AC_5 + (UBITS (bit_buf, 5) - 5);

            i += tab->run;
            if (i >= 64)
                break;  /* end of block */

        normal_code:
            j = scan[i];
            bit_buf <<= tab->len;
            bits += tab->len + 1;
            val = (tab->level * quant_matrix[j]) >> 4;

            /* oddification */
            val = (val - 1) | 1;

            /* if (bitstream_get (1)) val = -val; */
            val = (val ^ SBITS (bit_buf, 1)) - SBITS (bit_buf, 1);

            SATURATE (val);
            dest[j] = val;

            bit_buf <<= 1;
            NEEDBITS (bit_buf, bits, bit_ptr);

            continue;

        } else if (bit_buf >= 0x04000000) {

            tab = DCT_B14_8 + (UBITS (bit_buf, 8) - 4);

            i += tab->run;
            if (i < 64)
                goto normal_code;

            /* escape code */

            i += UBITS (bit_buf << 6, 6) - 64;
            if (i >= 64)
                break;  /* illegal, check needed to avoid buffer overflow */

            j = scan[i];

            DUMPBITS (bit_buf, bits, 12);
            NEEDBITS (bit_buf, bits, bit_ptr);
            val = SBITS (bit_buf, 8);
            if (! (val & 0x7f)) {
                DUMPBITS (bit_buf, bits, 8);
                val = UBITS (bit_buf, 8) + 2 * val;
            }
            val = (val * quant_matrix[j]) / 16;

            /* oddification */
            val = (val + ~SBITS (val, 1)) | 1;

            SATURATE (val);
            dest[j] = val;

            DUMPBITS (bit_buf, bits, 8);
            NEEDBITS (bit_buf, bits, bit_ptr);

            continue;

        } else if (bit_buf >= 0x02000000) {
            tab = DCT_B14_10 + (UBITS (bit_buf, 10) - 8);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else if (bit_buf >= 0x00800000) {
            tab = DCT_13 + (UBITS (bit_buf, 13) - 16);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else if (bit_buf >= 0x00200000) {
            tab = DCT_15 + (UBITS (bit_buf, 15) - 16);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else {
            tab = DCT_16 + UBITS (bit_buf, 16);
            bit_buf <<= 16;
            GETWORD (bit_buf, bits + 16, bit_ptr);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        }
        break;  /* illegal, check needed to avoid buffer overflow */
    }
    DUMPBITS (bit_buf, bits, tab->len); /* dump end of block code */
    decoder->bitstream_buf = bit_buf;
    decoder->bitstream_bits = bits;
    decoder->bitstream_ptr = bit_ptr;
}

static int get_mpeg1_non_intra_block (mpeg2_decoder_t * const decoder)
{
    int i;
    int j;
    int val;
    const uint8_t * const scan = decoder->scan;
    const uint16_t * const quant_matrix = decoder->quantizer_matrix[1];
    const DCTtab * tab;
    uint32_t bit_buf;
    int bits;
    const uint8_t * bit_ptr;
    int16_t * const dest = decoder->DCTblock;

    i = -1;

    bit_buf = decoder->bitstream_buf;
    bits = decoder->bitstream_bits;
    bit_ptr = decoder->bitstream_ptr;

    NEEDBITS (bit_buf, bits, bit_ptr);
    if (bit_buf >= 0x28000000) {
        tab = DCT_B14DC_5 + (UBITS (bit_buf, 5) - 5);
        goto entry_1;
    } else
        goto entry_2;

    while (1) {
        if (bit_buf >= 0x28000000) {

            tab = DCT_B14AC_5 + (UBITS (bit_buf, 5) - 5);

        entry_1:
            i += tab->run;
            if (i >= 64)
                break;  /* end of block */

        normal_code:
            j = scan[i];
            bit_buf <<= tab->len;
            bits += tab->len + 1;
            val = ((2 * tab->level + 1) * quant_matrix[j]) >> 5;

            /* oddification */
            val = (val - 1) | 1;

            /* if (bitstream_get (1)) val = -val; */
            val = (val ^ SBITS (bit_buf, 1)) - SBITS (bit_buf, 1);

            SATURATE (val);
            dest[j] = val;

            bit_buf <<= 1;
            NEEDBITS (bit_buf, bits, bit_ptr);

            continue;

        }

    entry_2:
        if (bit_buf >= 0x04000000) {

            tab = DCT_B14_8 + (UBITS (bit_buf, 8) - 4);

            i += tab->run;
            if (i < 64)
                goto normal_code;

            /* escape code */

            i += UBITS (bit_buf << 6, 6) - 64;
            if (i >= 64)
                break;  /* illegal, check needed to avoid buffer overflow */

            j = scan[i];

            DUMPBITS (bit_buf, bits, 12);
            NEEDBITS (bit_buf, bits, bit_ptr);
            val = SBITS (bit_buf, 8);
            if (! (val & 0x7f)) {
                DUMPBITS (bit_buf, bits, 8);
                val = UBITS (bit_buf, 8) + 2 * val;
            }
            val = 2 * (val + SBITS (val, 1)) + 1;
            val = (val * quant_matrix[j]) / 32;

            /* oddification */
            val = (val + ~SBITS (val, 1)) | 1;

            SATURATE (val);
            dest[j] = val;

            DUMPBITS (bit_buf, bits, 8);
            NEEDBITS (bit_buf, bits, bit_ptr);

            continue;

        } else if (bit_buf >= 0x02000000) {
            tab = DCT_B14_10 + (UBITS (bit_buf, 10) - 8);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else if (bit_buf >= 0x00800000) {
            tab = DCT_13 + (UBITS (bit_buf, 13) - 16);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else if (bit_buf >= 0x00200000) {
            tab = DCT_15 + (UBITS (bit_buf, 15) - 16);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        } else {
            tab = DCT_16 + UBITS (bit_buf, 16);
            bit_buf <<= 16;
            GETWORD (bit_buf, bits + 16, bit_ptr);
            i += tab->run;
            if (i < 64)
                goto normal_code;
        }
        break;  /* illegal, check needed to avoid buffer overflow */
    }
    DUMPBITS (bit_buf, bits, tab->len); /* dump end of block code */
    decoder->bitstream_buf = bit_buf;
    decoder->bitstream_bits = bits;
    decoder->bitstream_ptr = bit_ptr;
    return i;
}

static inline void slice_intra_DCT (mpeg2_decoder_t * const decoder,
                                    const int cc,
                                    uint8_t * const dest, const int stride)
{
#define bit_buf (decoder->bitstream_buf)
#define bits (decoder->bitstream_bits)
#define bit_ptr (decoder->bitstream_ptr)
    NEEDBITS (bit_buf, bits, bit_ptr);
    /* Get the intra DC coefficient and inverse quantize it */
    if (cc == 0)
        decoder->DCTblock[0] =
            decoder->dc_dct_pred[0] += get_luma_dc_dct_diff (decoder);
    else
        decoder->DCTblock[0] =
            decoder->dc_dct_pred[cc] += get_chroma_dc_dct_diff (decoder);

    if (decoder->mpeg1) {
        if (decoder->coding_type != D_TYPE)
            get_mpeg1_intra_block (decoder);
    } else if (decoder->intra_vlc_format)
        get_intra_block_B15 (decoder, decoder->quantizer_matrix[cc ? 2 : 0]);
    else
        get_intra_block_B14 (decoder, decoder->quantizer_matrix[cc ? 2 : 0]);
    mpeg2_idct_copy (decoder->DCTblock, dest, stride);
#undef bit_buf
#undef bits
#undef bit_ptr
}

static inline void slice_non_intra_DCT (mpeg2_decoder_t * const decoder,
                                        const int cc,
                                        uint8_t * const dest, const int stride)
{
    int last;

    if (decoder->mpeg1)
        last = get_mpeg1_non_intra_block (decoder);
    else
        last = get_non_intra_block (decoder,
                                    decoder->quantizer_matrix[cc ? 3 : 1]);
    mpeg2_idct_add (last, decoder->DCTblock, dest, stride);
}

#define MOTION_420(table,ref,motion_x,motion_y,size,y)                        \
    pos_x = 2 * decoder->offset + motion_x;                                   \
    pos_y = 2 * decoder->v_offset + motion_y + 2 * y;                         \
    if (unlikely (pos_x > decoder->limit_x)) {                                \
        pos_x = ((int)pos_x < 0) ? 0 : decoder->limit_x;                      \
        motion_x = pos_x - 2 * decoder->offset;                               \
    }                                                                         \
    if (unlikely (pos_y > decoder->limit_y_ ## size)) {                       \
        pos_y = ((int)pos_y < 0) ? 0 : decoder->limit_y_ ## size;             \
        motion_y = pos_y - 2 * decoder->v_offset - 2 * y;                     \
    }                                                                         \
    xy_half = ((pos_y & 1) << 1) | (pos_x & 1);                               \
    table[xy_half] (decoder->dest[0] + y * decoder->stride + decoder->offset, \
                    ref[0] + (pos_x >> 1) + (pos_y >> 1) * decoder->stride,   \
                    decoder->stride, size);                                   \
    motion_x /= 2;      motion_y /= 2;                                        \
    xy_half = ((motion_y & 1) << 1) | (motion_x & 1);                         \
    offset = (((decoder->offset + motion_x) >> 1) +                           \
              ((((decoder->v_offset + motion_y) >> 1) + y/2) *                \
               decoder->uv_stride));                                          \
    table[4+xy_half] (decoder->dest[1] + y/2 * decoder->uv_stride +           \
                      (decoder->offset >> 1), ref[1] + offset,                \
                      decoder->uv_stride, size/2);                            \
    table[4+xy_half] (decoder->dest[2] + y/2 * decoder->uv_stride +           \
                      (decoder->offset >> 1), ref[2] + offset,                \
                      decoder->uv_stride, size/2)

#define MOTION_FIELD_420(table,ref,motion_x,motion_y,dest_field,op,src_field) \
    pos_x = 2 * decoder->offset + motion_x;                                   \
    pos_y = decoder->v_offset + motion_y;                                     \
    if (unlikely (pos_x > decoder->limit_x)) {                                \
        pos_x = ((int)pos_x < 0) ? 0 : decoder->limit_x;                      \
        motion_x = pos_x - 2 * decoder->offset;                               \
    }                                                                         \
    if (unlikely (pos_y > decoder->limit_y)) {                                \
        pos_y = ((int)pos_y < 0) ? 0 : decoder->limit_y;                      \
        motion_y = pos_y - decoder->v_offset;                                 \
    }                                                                         \
    xy_half = ((pos_y & 1) << 1) | (pos_x & 1);                               \
    table[xy_half] (decoder->dest[0] + dest_field * decoder->stride +         \
                    decoder->offset,                                          \
                    (ref[0] + (pos_x >> 1) +                                  \
                     ((pos_y op) + src_field) * decoder->stride),             \
                    2 * decoder->stride, 8);                                  \
    motion_x /= 2;      motion_y /= 2;                                        \
    xy_half = ((motion_y & 1) << 1) | (motion_x & 1);                         \
    offset = (((decoder->offset + motion_x) >> 1) +                           \
              (((decoder->v_offset >> 1) + (motion_y op) + src_field) *       \
               decoder->uv_stride));                                          \
    table[4+xy_half] (decoder->dest[1] + dest_field * decoder->uv_stride +    \
                      (decoder->offset >> 1), ref[1] + offset,                \
                      2 * decoder->uv_stride, 4);                             \
    table[4+xy_half] (decoder->dest[2] + dest_field * decoder->uv_stride +    \
                      (decoder->offset >> 1), ref[2] + offset,                \
                      2 * decoder->uv_stride, 4)

#define MOTION_DMV_420(table,ref,motion_x,motion_y)                           \
    pos_x = 2 * decoder->offset + motion_x;                                   \
    pos_y = decoder->v_offset + motion_y;                                     \
    if (unlikely (pos_x > decoder->limit_x)) {                                \
        pos_x = ((int)pos_x < 0) ? 0 : decoder->limit_x;                      \
        motion_x = pos_x - 2 * decoder->offset;                               \
    }                                                                         \
    if (unlikely (pos_y > decoder->limit_y)) {                                \
        pos_y = ((int)pos_y < 0) ? 0 : decoder->limit_y;                      \
        motion_y = pos_y - decoder->v_offset;                                 \
    }                                                                         \
    xy_half = ((pos_y & 1) << 1) | (pos_x & 1);                               \
    offset = (pos_x >> 1) + (pos_y & ~1) * decoder->stride;                   \
    table[xy_half] (decoder->dest[0] + decoder->offset,                       \
                    ref[0] + offset, 2 * decoder->stride, 8);                 \
    table[xy_half] (decoder->dest[0] + decoder->stride + decoder->offset,     \
                    ref[0] + decoder->stride + offset,                        \
                    2 * decoder->stride, 8);                                  \
    motion_x /= 2;      motion_y /= 2;                                        \
    xy_half = ((motion_y & 1) << 1) | (motion_x & 1);                         \
    offset = (((decoder->offset + motion_x) >> 1) +                           \
              (((decoder->v_offset >> 1) + (motion_y & ~1)) *                 \
               decoder->uv_stride));                                          \
    table[4+xy_half] (decoder->dest[1] + (decoder->offset >> 1),              \
                      ref[1] + offset, 2 * decoder->uv_stride, 4);            \
    table[4+xy_half] (decoder->dest[1] + decoder->uv_stride +                 \
                      (decoder->offset >> 1),                                 \
                      ref[1] + decoder->uv_stride + offset,                   \
                      2 * decoder->uv_stride, 4);                             \
    table[4+xy_half] (decoder->dest[2] + (decoder->offset >> 1),              \
                      ref[2] + offset, 2 * decoder->uv_stride, 4);            \
    table[4+xy_half] (decoder->dest[2] + decoder->uv_stride +                 \
                      (decoder->offset >> 1),                                 \
                      ref[2] + decoder->uv_stride + offset,                   \
                      2 * decoder->uv_stride, 4)

#define MOTION_ZERO_420(table,ref)                                            \
    table[0] (decoder->dest[0] + decoder->offset,                             \
              (ref[0] + decoder->offset +                                     \
               decoder->v_offset * decoder->stride), decoder->stride, 16);    \
    offset = ((decoder->offset >> 1) +                                        \
              (decoder->v_offset >> 1) * decoder->uv_stride);                 \
    table[4] (decoder->dest[1] + (decoder->offset >> 1),                      \
              ref[1] + offset, decoder->uv_stride, 8);                        \
    table[4] (decoder->dest[2] + (decoder->offset >> 1),                      \
              ref[2] + offset, decoder->uv_stride, 8)

#define MOTION_422(table,ref,motion_x,motion_y,size,y)                        \
    pos_x = 2 * decoder->offset + motion_x;                                   \
    pos_y = 2 * decoder->v_offset + motion_y + 2 * y;                         \
    if (unlikely (pos_x > decoder->limit_x)) {                                \
        pos_x = ((int)pos_x < 0) ? 0 : decoder->limit_x;                      \
        motion_x = pos_x - 2 * decoder->offset;                               \
    }                                                                         \
    if (unlikely (pos_y > decoder->limit_y_ ## size)) {                       \
        pos_y = ((int)pos_y < 0) ? 0 : decoder->limit_y_ ## size;             \
        motion_y = pos_y - 2 * decoder->v_offset - 2 * y;                     \
    }                                                                         \
    xy_half = ((pos_y & 1) << 1) | (pos_x & 1);                               \
    offset = (pos_x >> 1) + (pos_y >> 1) * decoder->stride;                   \
    table[xy_half] (decoder->dest[0] + y * decoder->stride + decoder->offset, \
                    ref[0] + offset, decoder->stride, size);                  \
    offset = (offset + (motion_x & (motion_x < 0))) >> 1;                     \
    motion_x /= 2;                                                            \
    xy_half = ((pos_y & 1) << 1) | (motion_x & 1);                            \
    table[4+xy_half] (decoder->dest[1] + y * decoder->uv_stride +             \
                      (decoder->offset >> 1), ref[1] + offset,                \
                      decoder->uv_stride, size);                              \
    table[4+xy_half] (decoder->dest[2] + y * decoder->uv_stride +             \
                      (decoder->offset >> 1), ref[2] + offset,                \
                      decoder->uv_stride, size)

#define MOTION_FIELD_422(table,ref,motion_x,motion_y,dest_field,op,src_field) \
    pos_x = 2 * decoder->offset + motion_x;                                   \
    pos_y = decoder->v_offset + motion_y;                                     \
    if (unlikely (pos_x > decoder->limit_x)) {                                \
        pos_x = ((int)pos_x < 0) ? 0 : decoder->limit_x;                      \
        motion_x = pos_x - 2 * decoder->offset;                               \
    }                                                                         \
    if (unlikely (pos_y > decoder->limit_y)) {                                \
        pos_y = ((int)pos_y < 0) ? 0 : decoder->limit_y;                      \
        motion_y = pos_y - decoder->v_offset;                                 \
    }                                                                         \
    xy_half = ((pos_y & 1) << 1) | (pos_x & 1);                               \
    offset = (pos_x >> 1) + ((pos_y op) + src_field) * decoder->stride;       \
    table[xy_half] (decoder->dest[0] + dest_field * decoder->stride +         \
                    decoder->offset, ref[0] + offset,                         \
                    2 * decoder->stride, 8);                                  \
    offset = (offset + (motion_x & (motion_x < 0))) >> 1;                     \
    motion_x /= 2;                                                            \
    xy_half = ((pos_y & 1) << 1) | (motion_x & 1);                            \
    table[4+xy_half] (decoder->dest[1] + dest_field * decoder->uv_stride +    \
                      (decoder->offset >> 1), ref[1] + offset,                \
                      2 * decoder->uv_stride, 8);                             \
    table[4+xy_half] (decoder->dest[2] + dest_field * decoder->uv_stride +    \
                      (decoder->offset >> 1), ref[2] + offset,                \
                      2 * decoder->uv_stride, 8)

#define MOTION_DMV_422(table,ref,motion_x,motion_y)                           \
    pos_x = 2 * decoder->offset + motion_x;                                   \
    pos_y = decoder->v_offset + motion_y;                                     \
    if (unlikely (pos_x > decoder->limit_x)) {                                \
        pos_x = ((int)pos_x < 0) ? 0 : decoder->limit_x;                      \
        motion_x = pos_x - 2 * decoder->offset;                               \
    }                                                                         \
    if (unlikely (pos_y > decoder->limit_y)) {                                \
        pos_y = ((int)pos_y < 0) ? 0 : decoder->limit_y;                      \
        motion_y = pos_y - decoder->v_offset;                                 \
    }                                                                         \
    xy_half = ((pos_y & 1) << 1) | (pos_x & 1);                               \
    offset = (pos_x >> 1) + (pos_y & ~1) * decoder->stride;                   \
    table[xy_half] (decoder->dest[0] + decoder->offset,                       \
                    ref[0] + offset, 2 * decoder->stride, 8);                 \
    table[xy_half] (decoder->dest[0] + decoder->stride + decoder->offset,     \
                    ref[0] + decoder->stride + offset,                        \
                    2 * decoder->stride, 8);                                  \
    offset = (offset + (motion_x & (motion_x < 0))) >> 1;                     \
    motion_x /= 2;                                                            \
    xy_half = ((pos_y & 1) << 1) | (motion_x & 1);                            \
    table[4+xy_half] (decoder->dest[1] + (decoder->offset >> 1),              \
                      ref[1] + offset, 2 * decoder->uv_stride, 8);            \
    table[4+xy_half] (decoder->dest[1] + decoder->uv_stride +                 \
                      (decoder->offset >> 1),                                 \
                      ref[1] + decoder->uv_stride + offset,                   \
                      2 * decoder->uv_stride, 8);                             \
    table[4+xy_half] (decoder->dest[2] + (decoder->offset >> 1),              \
                      ref[2] + offset, 2 * decoder->uv_stride, 8);            \
    table[4+xy_half] (decoder->dest[2] + decoder->uv_stride +                 \
                      (decoder->offset >> 1),                                 \
                      ref[2] + decoder->uv_stride + offset,                   \
                      2 * decoder->uv_stride, 8)

#define MOTION_ZERO_422(table,ref)                                            \
    offset = decoder->offset + decoder->v_offset * decoder->stride;           \
    table[0] (decoder->dest[0] + decoder->offset,                             \
              ref[0] + offset, decoder->stride, 16);                          \
    offset >>= 1;                                                             \
    table[4] (decoder->dest[1] + (decoder->offset >> 1),                      \
              ref[1] + offset, decoder->uv_stride, 16);                       \
    table[4] (decoder->dest[2] + (decoder->offset >> 1),                      \
              ref[2] + offset, decoder->uv_stride, 16)

#define MOTION_444(table,ref,motion_x,motion_y,size,y)                        \
    pos_x = 2 * decoder->offset + motion_x;                                   \
    pos_y = 2 * decoder->v_offset + motion_y + 2 * y;                         \
    if (unlikely (pos_x > decoder->limit_x)) {                                \
        pos_x = ((int)pos_x < 0) ? 0 : decoder->limit_x;                      \
        motion_x = pos_x - 2 * decoder->offset;                               \
    }                                                                         \
    if (unlikely (pos_y > decoder->limit_y_ ## size)) {                       \
        pos_y = ((int)pos_y < 0) ? 0 : decoder->limit_y_ ## size;             \
        motion_y = pos_y - 2 * decoder->v_offset - 2 * y;                     \
    }                                                                         \
    xy_half = ((pos_y & 1) << 1) | (pos_x & 1);                               \
    offset = (pos_x >> 1) + (pos_y >> 1) * decoder->stride;                   \
    table[xy_half] (decoder->dest[0] + y * decoder->stride + decoder->offset, \
                    ref[0] + offset, decoder->stride, size);                  \
    table[xy_half] (decoder->dest[1] + y * decoder->stride + decoder->offset, \
                    ref[1] + offset, decoder->stride, size);                  \
    table[xy_half] (decoder->dest[2] + y * decoder->stride + decoder->offset, \
                    ref[2] + offset, decoder->stride, size)

#define MOTION_FIELD_444(table,ref,motion_x,motion_y,dest_field,op,src_field) \
    pos_x = 2 * decoder->offset + motion_x;                                   \
    pos_y = decoder->v_offset + motion_y;                                     \
    if (unlikely (pos_x > decoder->limit_x)) {                                \
        pos_x = ((int)pos_x < 0) ? 0 : decoder->limit_x;                      \
        motion_x = pos_x - 2 * decoder->offset;                               \
    }                                                                         \
    if (unlikely (pos_y > decoder->limit_y)) {                                \
        pos_y = ((int)pos_y < 0) ? 0 : decoder->limit_y;                      \
        motion_y = pos_y - decoder->v_offset;                                 \
    }                                                                         \
    xy_half = ((pos_y & 1) << 1) | (pos_x & 1);                               \
    offset = (pos_x >> 1) + ((pos_y op) + src_field) * decoder->stride;       \
    table[xy_half] (decoder->dest[0] + dest_field * decoder->stride +         \
                    decoder->offset, ref[0] + offset,                         \
                    2 * decoder->stride, 8);                                  \
    table[xy_half] (decoder->dest[1] + dest_field * decoder->stride +         \
                    decoder->offset, ref[1] + offset,                         \
                    2 * decoder->stride, 8);                                  \
    table[xy_half] (decoder->dest[2] + dest_field * decoder->stride +         \
                    decoder->offset, ref[2] + offset,                         \
                    2 * decoder->stride, 8)

#define MOTION_DMV_444(table,ref,motion_x,motion_y)                           \
    pos_x = 2 * decoder->offset + motion_x;                                   \
    pos_y = decoder->v_offset + motion_y;                                     \
    if (unlikely (pos_x > decoder->limit_x)) {                                \
        pos_x = ((int)pos_x < 0) ? 0 : decoder->limit_x;                      \
        motion_x = pos_x - 2 * decoder->offset;                               \
    }                                                                         \
    if (unlikely (pos_y > decoder->limit_y)) {                                \
        pos_y = ((int)pos_y < 0) ? 0 : decoder->limit_y;                      \
        motion_y = pos_y - decoder->v_offset;                                 \
    }                                                                         \
    xy_half = ((pos_y & 1) << 1) | (pos_x & 1);                               \
    offset = (pos_x >> 1) + (pos_y & ~1) * decoder->stride;                   \
    table[xy_half] (decoder->dest[0] + decoder->offset,                       \
                    ref[0] + offset, 2 * decoder->stride, 8);                 \
    table[xy_half] (decoder->dest[0] + decoder->stride + decoder->offset,     \
                    ref[0] + decoder->stride + offset,                        \
                    2 * decoder->stride, 8);                                  \
    table[xy_half] (decoder->dest[1] + decoder->offset,                       \
                    ref[1] + offset, 2 * decoder->stride, 8);                 \
    table[xy_half] (decoder->dest[1] + decoder->stride + decoder->offset,     \
                    ref[1] + decoder->stride + offset,                        \
                    2 * decoder->stride, 8);                                  \
    table[xy_half] (decoder->dest[2] + decoder->offset,                       \
                    ref[2] + offset, 2 * decoder->stride, 8);                 \
    table[xy_half] (decoder->dest[2] + decoder->stride + decoder->offset,     \
                    ref[2] + decoder->stride + offset,                        \
                    2 * decoder->stride, 8)

#define MOTION_ZERO_444(table,ref)                                            \
    offset = decoder->offset + decoder->v_offset * decoder->stride;           \
    table[0] (decoder->dest[0] + decoder->offset,                             \
              ref[0] + offset, decoder->stride, 16);                          \
    table[4] (decoder->dest[1] + decoder->offset,                             \
              ref[1] + offset, decoder->stride, 16);                          \
    table[4] (decoder->dest[2] + decoder->offset,                             \
              ref[2] + offset, decoder->stride, 16)

#define bit_buf (decoder->bitstream_buf)
#define bits (decoder->bitstream_bits)
#define bit_ptr (decoder->bitstream_ptr)

static void motion_mp1 (mpeg2_decoder_t * const decoder,
                        motion_t * const motion,
                        mpeg2_mc_fct * const * const table)
{
    int motion_x, motion_y;
    unsigned int pos_x, pos_y, xy_half, offset;

    NEEDBITS (bit_buf, bits, bit_ptr);
    motion_x = (motion->pmv[0][0] +
                (get_motion_delta (decoder,
                                   motion->f_code[0]) << motion->f_code[1]));
    motion_x = bound_motion_vector (motion_x,
                                    motion->f_code[0] + motion->f_code[1]);
    motion->pmv[0][0] = motion_x;

    NEEDBITS (bit_buf, bits, bit_ptr);
    motion_y = (motion->pmv[0][1] +
                (get_motion_delta (decoder,
                                   motion->f_code[0]) << motion->f_code[1]));
    motion_y = bound_motion_vector (motion_y,
                                    motion->f_code[0] + motion->f_code[1]);
    motion->pmv[0][1] = motion_y;

    MOTION_420 (table, motion->ref[0], motion_x, motion_y, 16, 0);
}

#define MOTION_FUNCTIONS(FORMAT,MOTION,MOTION_FIELD,MOTION_DMV,MOTION_ZERO)   \
                                                                              \
static void motion_fr_frame_##FORMAT (mpeg2_decoder_t * const decoder,        \
                                      motion_t * const motion,                \
                                      mpeg2_mc_fct * const * const table)     \
{                                                                             \
    int motion_x, motion_y;                                                   \
    unsigned int pos_x, pos_y, xy_half, offset;                               \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    motion_x = motion->pmv[0][0] + get_motion_delta (decoder,                 \
                                                     motion->f_code[0]);      \
    motion_x = bound_motion_vector (motion_x, motion->f_code[0]);             \
    motion->pmv[1][0] = motion->pmv[0][0] = motion_x;                         \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    motion_y = motion->pmv[0][1] + get_motion_delta (decoder,                 \
                                                     motion->f_code[1]);      \
    motion_y = bound_motion_vector (motion_y, motion->f_code[1]);             \
    motion->pmv[1][1] = motion->pmv[0][1] = motion_y;                         \
                                                                              \
    MOTION (table, motion->ref[0], motion_x, motion_y, 16, 0);                \
}                                                                             \
                                                                              \
static void motion_fr_field_##FORMAT (mpeg2_decoder_t * const decoder,        \
                                      motion_t * const motion,                \
                                      mpeg2_mc_fct * const * const table)     \
{                                                                             \
    int motion_x, motion_y, field;                                            \
    unsigned int pos_x, pos_y, xy_half, offset;                               \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    field = UBITS (bit_buf, 1);                                               \
    DUMPBITS (bit_buf, bits, 1);                                              \
                                                                              \
    motion_x = motion->pmv[0][0] + get_motion_delta (decoder,                 \
                                                     motion->f_code[0]);      \
    motion_x = bound_motion_vector (motion_x, motion->f_code[0]);             \
    motion->pmv[0][0] = motion_x;                                             \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    motion_y = ((motion->pmv[0][1] >> 1) +                                    \
                get_motion_delta (decoder, motion->f_code[1]));               \
    /* motion_y = bound_motion_vector (motion_y, motion->f_code[1]); */       \
    motion->pmv[0][1] = motion_y << 1;                                        \
                                                                              \
    MOTION_FIELD (table, motion->ref[0], motion_x, motion_y, 0, & ~1, field); \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    field = UBITS (bit_buf, 1);                                               \
    DUMPBITS (bit_buf, bits, 1);                                              \
                                                                              \
    motion_x = motion->pmv[1][0] + get_motion_delta (decoder,                 \
                                                     motion->f_code[0]);      \
    motion_x = bound_motion_vector (motion_x, motion->f_code[0]);             \
    motion->pmv[1][0] = motion_x;                                             \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    motion_y = ((motion->pmv[1][1] >> 1) +                                    \
                get_motion_delta (decoder, motion->f_code[1]));               \
    /* motion_y = bound_motion_vector (motion_y, motion->f_code[1]); */       \
    motion->pmv[1][1] = motion_y << 1;                                        \
                                                                              \
    MOTION_FIELD (table, motion->ref[0], motion_x, motion_y, 1, & ~1, field); \
}                                                                             \
                                                                              \
static void motion_fr_dmv_##FORMAT (mpeg2_decoder_t * const decoder,          \
                                    motion_t * const motion,                  \
                                    mpeg2_mc_fct * const * const table)       \
{                                                                             \
    int motion_x, motion_y, dmv_x, dmv_y, m, other_x, other_y;                \
    unsigned int pos_x, pos_y, xy_half, offset;                               \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    motion_x = motion->pmv[0][0] + get_motion_delta (decoder,                 \
                                                     motion->f_code[0]);      \
    motion_x = bound_motion_vector (motion_x, motion->f_code[0]);             \
    motion->pmv[1][0] = motion->pmv[0][0] = motion_x;                         \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    dmv_x = get_dmv (decoder);                                                \
                                                                              \
    motion_y = ((motion->pmv[0][1] >> 1) +                                    \
                get_motion_delta (decoder, motion->f_code[1]));               \
    /* motion_y = bound_motion_vector (motion_y, motion->f_code[1]); */       \
    motion->pmv[1][1] = motion->pmv[0][1] = motion_y << 1;                    \
    dmv_y = get_dmv (decoder);                                                \
                                                                              \
    m = decoder->top_field_first ? 1 : 3;                                     \
    other_x = ((motion_x * m + (motion_x > 0)) >> 1) + dmv_x;                 \
    other_y = ((motion_y * m + (motion_y > 0)) >> 1) + dmv_y - 1;             \
    MOTION_FIELD (mpeg2_mc.put, motion->ref[0], other_x, other_y, 0, | 1, 0); \
                                                                              \
    m = decoder->top_field_first ? 3 : 1;                                     \
    other_x = ((motion_x * m + (motion_x > 0)) >> 1) + dmv_x;                 \
    other_y = ((motion_y * m + (motion_y > 0)) >> 1) + dmv_y + 1;             \
    MOTION_FIELD (mpeg2_mc.put, motion->ref[0], other_x, other_y, 1, & ~1, 0);\
                                                                              \
    MOTION_DMV (mpeg2_mc.avg, motion->ref[0], motion_x, motion_y);            \
}                                                                             \
                                                                              \
static void motion_reuse_##FORMAT (mpeg2_decoder_t * const decoder,           \
                                   motion_t * const motion,                   \
                                   mpeg2_mc_fct * const * const table)        \
{                                                                             \
    int motion_x, motion_y;                                                   \
    unsigned int pos_x, pos_y, xy_half, offset;                               \
                                                                              \
    motion_x = motion->pmv[0][0];                                             \
    motion_y = motion->pmv[0][1];                                             \
                                                                              \
    MOTION (table, motion->ref[0], motion_x, motion_y, 16, 0);                \
}                                                                             \
                                                                              \
static void motion_zero_##FORMAT (mpeg2_decoder_t * const decoder,            \
                                  motion_t * const motion,                    \
                                  mpeg2_mc_fct * const * const table)         \
{                                                                             \
    unsigned int offset;                                                      \
                                                                              \
    motion->pmv[0][0] = motion->pmv[0][1] = 0;                                \
    motion->pmv[1][0] = motion->pmv[1][1] = 0;                                \
                                                                              \
    MOTION_ZERO (table, motion->ref[0]);                                      \
}                                                                             \
                                                                              \
static void motion_fi_field_##FORMAT (mpeg2_decoder_t * const decoder,        \
                                      motion_t * const motion,                \
                                      mpeg2_mc_fct * const * const table)     \
{                                                                             \
    int motion_x, motion_y;                                                   \
    uint8_t ** ref_field;                                                     \
    unsigned int pos_x, pos_y, xy_half, offset;                               \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    ref_field = motion->ref2[UBITS (bit_buf, 1)];                             \
    DUMPBITS (bit_buf, bits, 1);                                              \
                                                                              \
    motion_x = motion->pmv[0][0] + get_motion_delta (decoder,                 \
                                                     motion->f_code[0]);      \
    motion_x = bound_motion_vector (motion_x, motion->f_code[0]);             \
    motion->pmv[1][0] = motion->pmv[0][0] = motion_x;                         \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    motion_y = motion->pmv[0][1] + get_motion_delta (decoder,                 \
                                                     motion->f_code[1]);      \
    motion_y = bound_motion_vector (motion_y, motion->f_code[1]);             \
    motion->pmv[1][1] = motion->pmv[0][1] = motion_y;                         \
                                                                              \
    MOTION (table, ref_field, motion_x, motion_y, 16, 0);                     \
}                                                                             \
                                                                              \
static void motion_fi_16x8_##FORMAT (mpeg2_decoder_t * const decoder,         \
                                     motion_t * const motion,                 \
                                     mpeg2_mc_fct * const * const table)      \
{                                                                             \
    int motion_x, motion_y;                                                   \
    uint8_t ** ref_field;                                                     \
    unsigned int pos_x, pos_y, xy_half, offset;                               \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    ref_field = motion->ref2[UBITS (bit_buf, 1)];                             \
    DUMPBITS (bit_buf, bits, 1);                                              \
                                                                              \
    motion_x = motion->pmv[0][0] + get_motion_delta (decoder,                 \
                                                     motion->f_code[0]);      \
    motion_x = bound_motion_vector (motion_x, motion->f_code[0]);             \
    motion->pmv[0][0] = motion_x;                                             \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    motion_y = motion->pmv[0][1] + get_motion_delta (decoder,                 \
                                                     motion->f_code[1]);      \
    motion_y = bound_motion_vector (motion_y, motion->f_code[1]);             \
    motion->pmv[0][1] = motion_y;                                             \
                                                                              \
    MOTION (table, ref_field, motion_x, motion_y, 8, 0);                      \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    ref_field = motion->ref2[UBITS (bit_buf, 1)];                             \
    DUMPBITS (bit_buf, bits, 1);                                              \
                                                                              \
    motion_x = motion->pmv[1][0] + get_motion_delta (decoder,                 \
                                                     motion->f_code[0]);      \
    motion_x = bound_motion_vector (motion_x, motion->f_code[0]);             \
    motion->pmv[1][0] = motion_x;                                             \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    motion_y = motion->pmv[1][1] + get_motion_delta (decoder,                 \
                                                     motion->f_code[1]);      \
    motion_y = bound_motion_vector (motion_y, motion->f_code[1]);             \
    motion->pmv[1][1] = motion_y;                                             \
                                                                              \
    MOTION (table, ref_field, motion_x, motion_y, 8, 8);                      \
}                                                                             \
                                                                              \
static void motion_fi_dmv_##FORMAT (mpeg2_decoder_t * const decoder,          \
                                    motion_t * const motion,                  \
                                    mpeg2_mc_fct * const * const table)       \
{                                                                             \
    int motion_x, motion_y, other_x, other_y;                                 \
    unsigned int pos_x, pos_y, xy_half, offset;                               \
                                                                              \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    motion_x = motion->pmv[0][0] + get_motion_delta (decoder,                 \
                                                     motion->f_code[0]);      \
    motion_x = bound_motion_vector (motion_x, motion->f_code[0]);             \
    motion->pmv[1][0] = motion->pmv[0][0] = motion_x;                         \
    NEEDBITS (bit_buf, bits, bit_ptr);                                        \
    other_x = ((motion_x + (motion_x > 0)) >> 1) + get_dmv (decoder);         \
                                                                              \
    motion_y = motion->pmv[0][1] + get_motion_delta (decoder,                 \
                                                     motion->f_code[1]);      \
    motion_y = bound_motion_vector (motion_y, motion->f_code[1]);             \
    motion->pmv[1][1] = motion->pmv[0][1] = motion_y;                         \
    other_y = (((motion_y + (motion_y > 0)) >> 1) + get_dmv (decoder) +       \
               decoder->dmv_offset);                                          \
                                                                              \
    MOTION (mpeg2_mc.put, motion->ref[0], motion_x, motion_y, 16, 0);         \
    MOTION (mpeg2_mc.avg, motion->ref[1], other_x, other_y, 16, 0);           \
}                                                                             \

MOTION_FUNCTIONS (420, MOTION_420, MOTION_FIELD_420, MOTION_DMV_420,
                  MOTION_ZERO_420)
MOTION_FUNCTIONS (422, MOTION_422, MOTION_FIELD_422, MOTION_DMV_422,
                  MOTION_ZERO_422)
MOTION_FUNCTIONS (444, MOTION_444, MOTION_FIELD_444, MOTION_DMV_444,
                  MOTION_ZERO_444)

/* like motion_frame, but parsing without actual motion compensation */
static void motion_fr_conceal (mpeg2_decoder_t * const decoder)
{
    int tmp;

    NEEDBITS (bit_buf, bits, bit_ptr);
    tmp = (decoder->f_motion.pmv[0][0] +
           get_motion_delta (decoder, decoder->f_motion.f_code[0]));
    tmp = bound_motion_vector (tmp, decoder->f_motion.f_code[0]);
    decoder->f_motion.pmv[1][0] = decoder->f_motion.pmv[0][0] = tmp;

    NEEDBITS (bit_buf, bits, bit_ptr);
    tmp = (decoder->f_motion.pmv[0][1] +
           get_motion_delta (decoder, decoder->f_motion.f_code[1]));
    tmp = bound_motion_vector (tmp, decoder->f_motion.f_code[1]);
    decoder->f_motion.pmv[1][1] = decoder->f_motion.pmv[0][1] = tmp;

    DUMPBITS (bit_buf, bits, 1); /* remove marker_bit */
}

static void motion_fi_conceal (mpeg2_decoder_t * const decoder)
{
    int tmp;

    NEEDBITS (bit_buf, bits, bit_ptr);
    DUMPBITS (bit_buf, bits, 1); /* remove field_select */

    tmp = (decoder->f_motion.pmv[0][0] +
           get_motion_delta (decoder, decoder->f_motion.f_code[0]));
    tmp = bound_motion_vector (tmp, decoder->f_motion.f_code[0]);
    decoder->f_motion.pmv[1][0] = decoder->f_motion.pmv[0][0] = tmp;

    NEEDBITS (bit_buf, bits, bit_ptr);
    tmp = (decoder->f_motion.pmv[0][1] +
           get_motion_delta (decoder, decoder->f_motion.f_code[1]));
    tmp = bound_motion_vector (tmp, decoder->f_motion.f_code[1]);
    decoder->f_motion.pmv[1][1] = decoder->f_motion.pmv[0][1] = tmp;

    DUMPBITS (bit_buf, bits, 1); /* remove marker_bit */
}

#undef bit_buf
#undef bits
#undef bit_ptr

#define MOTION_CALL(routine,direction)                          \
do {                                                            \
    if ((direction) & MACROBLOCK_MOTION_FORWARD)                \
        routine (decoder, &(decoder->f_motion), mpeg2_mc.put);  \
    if ((direction) & MACROBLOCK_MOTION_BACKWARD)               \
        routine (decoder, &(decoder->b_motion),                 \
                 ((direction) & MACROBLOCK_MOTION_FORWARD ?     \
                  mpeg2_mc.avg : mpeg2_mc.put));                \
} while (0)

#define NEXT_MACROBLOCK                                                 \
do {                                                                    \
    decoder->offset += 16;                                              \
    if (decoder->offset == decoder->width) {                            \
        do { /* just so we can use the break statement */               \
            if (decoder->convert) {                                     \
                decoder->convert (decoder->convert_id, decoder->dest,   \
                                  decoder->v_offset);                   \
                if (decoder->coding_type == B_TYPE)                     \
                    break;                                              \
            }                                                           \
            decoder->dest[0] += decoder->slice_stride;                  \
            decoder->dest[1] += decoder->slice_uv_stride;               \
            decoder->dest[2] += decoder->slice_uv_stride;               \
        } while (0);                                                    \
        decoder->v_offset += 16;                                        \
        if (decoder->v_offset > decoder->limit_y) {                     \
            if (mpeg2_cpu_state_restore)                                \
                mpeg2_cpu_state_restore (&cpu_state);                   \
            return;                                                     \
        }                                                               \
        decoder->offset = 0;                                            \
    }                                                                   \
} while (0)

void mpeg2_init_fbuf (mpeg2_decoder_t * decoder, uint8_t * current_fbuf[3],
                      uint8_t * forward_fbuf[3], uint8_t * backward_fbuf[3])
{
    int offset, stride, height, bottom_field;

    stride = decoder->stride_frame;
    bottom_field = (decoder->picture_structure == BOTTOM_FIELD);
    offset = bottom_field ? stride : 0;
    height = decoder->height;

    decoder->picture_dest[0] = current_fbuf[0] + offset;
    decoder->picture_dest[1] = current_fbuf[1] + (offset >> 1);
    decoder->picture_dest[2] = current_fbuf[2] + (offset >> 1);

    decoder->f_motion.ref[0][0] = forward_fbuf[0] + offset;
    decoder->f_motion.ref[0][1] = forward_fbuf[1] + (offset >> 1);
    decoder->f_motion.ref[0][2] = forward_fbuf[2] + (offset >> 1);

    decoder->b_motion.ref[0][0] = backward_fbuf[0] + offset;
    decoder->b_motion.ref[0][1] = backward_fbuf[1] + (offset >> 1);
    decoder->b_motion.ref[0][2] = backward_fbuf[2] + (offset >> 1);

    if (decoder->picture_structure != FRAME_PICTURE) {
        decoder->dmv_offset = bottom_field ? 1 : -1;
        decoder->f_motion.ref2[0] = decoder->f_motion.ref[bottom_field];
        decoder->f_motion.ref2[1] = decoder->f_motion.ref[!bottom_field];
        decoder->b_motion.ref2[0] = decoder->b_motion.ref[bottom_field];
        decoder->b_motion.ref2[1] = decoder->b_motion.ref[!bottom_field];
        offset = stride - offset;

        if (decoder->second_field && (decoder->coding_type != B_TYPE))
            forward_fbuf = current_fbuf;

        decoder->f_motion.ref[1][0] = forward_fbuf[0] + offset;
        decoder->f_motion.ref[1][1] = forward_fbuf[1] + (offset >> 1);
        decoder->f_motion.ref[1][2] = forward_fbuf[2] + (offset >> 1);

        decoder->b_motion.ref[1][0] = backward_fbuf[0] + offset;
        decoder->b_motion.ref[1][1] = backward_fbuf[1] + (offset >> 1);
        decoder->b_motion.ref[1][2] = backward_fbuf[2] + (offset >> 1);

        stride <<= 1;
        height >>= 1;
    }

    decoder->stride = stride;
    decoder->uv_stride = stride >> 1;
    decoder->slice_stride = 16 * stride;
    decoder->slice_uv_stride =
        decoder->slice_stride >> (2 - decoder->chroma_format);
    decoder->limit_x = 2 * decoder->width - 32;
    decoder->limit_y_16 = 2 * height - 32;
    decoder->limit_y_8 = 2 * height - 16;
    decoder->limit_y = height - 16;

    if (decoder->mpeg1) {
        decoder->motion_parser[0] = motion_zero_420;
        decoder->motion_parser[MC_FRAME] = motion_mp1;
        decoder->motion_parser[4] = motion_reuse_420;
    } else if (decoder->picture_structure == FRAME_PICTURE) {
        if (decoder->chroma_format == 0) {
            decoder->motion_parser[0] = motion_zero_420;
            decoder->motion_parser[MC_FIELD] = motion_fr_field_420;
            decoder->motion_parser[MC_FRAME] = motion_fr_frame_420;
            decoder->motion_parser[MC_DMV] = motion_fr_dmv_420;
            decoder->motion_parser[4] = motion_reuse_420;
        } else if (decoder->chroma_format == 1) {
            decoder->motion_parser[0] = motion_zero_422;
            decoder->motion_parser[MC_FIELD] = motion_fr_field_422;
            decoder->motion_parser[MC_FRAME] = motion_fr_frame_422;
            decoder->motion_parser[MC_DMV] = motion_fr_dmv_422;
            decoder->motion_parser[4] = motion_reuse_422;
        } else {
            decoder->motion_parser[0] = motion_zero_444;
            decoder->motion_parser[MC_FIELD] = motion_fr_field_444;
            decoder->motion_parser[MC_FRAME] = motion_fr_frame_444;
            decoder->motion_parser[MC_DMV] = motion_fr_dmv_444;
            decoder->motion_parser[4] = motion_reuse_444;
        }
    } else {
        if (decoder->chroma_format == 0) {
            decoder->motion_parser[0] = motion_zero_420;
            decoder->motion_parser[MC_FIELD] = motion_fi_field_420;
            decoder->motion_parser[MC_16X8] = motion_fi_16x8_420;
            decoder->motion_parser[MC_DMV] = motion_fi_dmv_420;
            decoder->motion_parser[4] = motion_reuse_420;
        } else if (decoder->chroma_format == 1) {
            decoder->motion_parser[0] = motion_zero_422;
            decoder->motion_parser[MC_FIELD] = motion_fi_field_422;
            decoder->motion_parser[MC_16X8] = motion_fi_16x8_422;
            decoder->motion_parser[MC_DMV] = motion_fi_dmv_422;
            decoder->motion_parser[4] = motion_reuse_422;
        } else {
            decoder->motion_parser[0] = motion_zero_444;
            decoder->motion_parser[MC_FIELD] = motion_fi_field_444;
            decoder->motion_parser[MC_16X8] = motion_fi_16x8_444;
            decoder->motion_parser[MC_DMV] = motion_fi_dmv_444;
            decoder->motion_parser[4] = motion_reuse_444;
        }
    }
}

static inline int slice_init (mpeg2_decoder_t * const decoder, int code)
{
#define bit_buf (decoder->bitstream_buf)
#define bits (decoder->bitstream_bits)
#define bit_ptr (decoder->bitstream_ptr)
    int offset;
    const MBAtab * mba;

    decoder->dc_dct_pred[0] = decoder->dc_dct_pred[1] =
        decoder->dc_dct_pred[2] = 16384;

    decoder->f_motion.pmv[0][0] = decoder->f_motion.pmv[0][1] = 0;
    decoder->f_motion.pmv[1][0] = decoder->f_motion.pmv[1][1] = 0;
    decoder->b_motion.pmv[0][0] = decoder->b_motion.pmv[0][1] = 0;
    decoder->b_motion.pmv[1][0] = decoder->b_motion.pmv[1][1] = 0;

    if (decoder->vertical_position_extension) {
        code += UBITS (bit_buf, 3) << 7;
        DUMPBITS (bit_buf, bits, 3);
    }
    decoder->v_offset = (code - 1) * 16;
    offset = 0;
    if (!(decoder->convert) || decoder->coding_type != B_TYPE)
        offset = (code - 1) * decoder->slice_stride;

    decoder->dest[0] = decoder->picture_dest[0] + offset;
    offset >>= (2 - decoder->chroma_format);
    decoder->dest[1] = decoder->picture_dest[1] + offset;
    decoder->dest[2] = decoder->picture_dest[2] + offset;

    get_quantizer_scale (decoder);

    /* ignore intra_slice and all the extra data */
    while (bit_buf & 0x80000000) {
        DUMPBITS (bit_buf, bits, 9);
        NEEDBITS (bit_buf, bits, bit_ptr);
    }

    /* decode initial macroblock address increment */
    offset = 0;
    while (1) {
        if (bit_buf >= 0x08000000) {
            mba = MBA_5 + (UBITS (bit_buf, 6) - 2);
            break;
        } else if (bit_buf >= 0x01800000) {
            mba = MBA_11 + (UBITS (bit_buf, 12) - 24);
            break;
        } else switch (UBITS (bit_buf, 12)) {
        case 8:         /* macroblock_escape */
            offset += 33;
            DUMPBITS (bit_buf, bits, 11);
            NEEDBITS (bit_buf, bits, bit_ptr);
            continue;
        case 15:        /* macroblock_stuffing (MPEG1 only) */
            bit_buf &= 0xfffff;
            DUMPBITS (bit_buf, bits, 11);
            NEEDBITS (bit_buf, bits, bit_ptr);
            continue;
        default:        /* error */
            return 1;
        }
    }
    DUMPBITS (bit_buf, bits, mba->len + 1);
    decoder->offset = (offset + mba->mba) << 4;

    while (decoder->offset - decoder->width >= 0) {
        decoder->offset -= decoder->width;
        if (!(decoder->convert) || decoder->coding_type != B_TYPE) {
            decoder->dest[0] += decoder->slice_stride;
            decoder->dest[1] += decoder->slice_uv_stride;
            decoder->dest[2] += decoder->slice_uv_stride;
        }
        decoder->v_offset += 16;
    }
    if (decoder->v_offset > decoder->limit_y)
        return 1;

    return 0;
#undef bit_buf
#undef bits
#undef bit_ptr
}

void mpeg2_slice (mpeg2_decoder_t * const decoder, const int code,
                  const uint8_t * const buffer)
{
#define bit_buf (decoder->bitstream_buf)
#define bits (decoder->bitstream_bits)
#define bit_ptr (decoder->bitstream_ptr)
    cpu_state_t cpu_state;

    bitstream_init (decoder, buffer);

    if (slice_init (decoder, code))
        return;

    if (mpeg2_cpu_state_save)
        mpeg2_cpu_state_save (&cpu_state);

    while (1) {
        int macroblock_modes;
        int mba_inc;
        const MBAtab * mba;

        NEEDBITS (bit_buf, bits, bit_ptr);

        macroblock_modes = get_macroblock_modes (decoder);

        /* maybe integrate MACROBLOCK_QUANT test into get_macroblock_modes ? */
        if (macroblock_modes & MACROBLOCK_QUANT)
            get_quantizer_scale (decoder);

        if (macroblock_modes & MACROBLOCK_INTRA) {

            int DCT_offset, DCT_stride;
            int offset;
            uint8_t * dest_y;

            if (decoder->concealment_motion_vectors) {
                if (decoder->picture_structure == FRAME_PICTURE)
                    motion_fr_conceal (decoder);
                else
                    motion_fi_conceal (decoder);
            } else {
                decoder->f_motion.pmv[0][0] = decoder->f_motion.pmv[0][1] = 0;
                decoder->f_motion.pmv[1][0] = decoder->f_motion.pmv[1][1] = 0;
                decoder->b_motion.pmv[0][0] = decoder->b_motion.pmv[0][1] = 0;
                decoder->b_motion.pmv[1][0] = decoder->b_motion.pmv[1][1] = 0;
            }

            if (macroblock_modes & DCT_TYPE_INTERLACED) {
                DCT_offset = decoder->stride;
                DCT_stride = decoder->stride * 2;
            } else {
                DCT_offset = decoder->stride * 8;
                DCT_stride = decoder->stride;
            }

            offset = decoder->offset;
            dest_y = decoder->dest[0] + offset;
            slice_intra_DCT (decoder, 0, dest_y, DCT_stride);
            slice_intra_DCT (decoder, 0, dest_y + 8, DCT_stride);
            slice_intra_DCT (decoder, 0, dest_y + DCT_offset, DCT_stride);
            slice_intra_DCT (decoder, 0, dest_y + DCT_offset + 8, DCT_stride);
            if (likely (decoder->chroma_format == 0)) {
                slice_intra_DCT (decoder, 1, decoder->dest[1] + (offset >> 1),
                                 decoder->uv_stride);
                slice_intra_DCT (decoder, 2, decoder->dest[2] + (offset >> 1),
                                 decoder->uv_stride);
                if (decoder->coding_type == D_TYPE) {
                    NEEDBITS (bit_buf, bits, bit_ptr);
                    DUMPBITS (bit_buf, bits, 1);
                }
            } else if (likely (decoder->chroma_format == 1)) {
                uint8_t * dest_u = decoder->dest[1] + (offset >> 1);
                uint8_t * dest_v = decoder->dest[2] + (offset >> 1);
                DCT_stride >>= 1;
                DCT_offset >>= 1;
                slice_intra_DCT (decoder, 1, dest_u, DCT_stride);
                slice_intra_DCT (decoder, 2, dest_v, DCT_stride);
                slice_intra_DCT (decoder, 1, dest_u + DCT_offset, DCT_stride);
                slice_intra_DCT (decoder, 2, dest_v + DCT_offset, DCT_stride);
            } else {
                uint8_t * dest_u = decoder->dest[1] + offset;
                uint8_t * dest_v = decoder->dest[2] + offset;
                slice_intra_DCT (decoder, 1, dest_u, DCT_stride);
                slice_intra_DCT (decoder, 2, dest_v, DCT_stride);
                slice_intra_DCT (decoder, 1, dest_u + DCT_offset, DCT_stride);
                slice_intra_DCT (decoder, 2, dest_v + DCT_offset, DCT_stride);
                slice_intra_DCT (decoder, 1, dest_u + 8, DCT_stride);
                slice_intra_DCT (decoder, 2, dest_v + 8, DCT_stride);
                slice_intra_DCT (decoder, 1, dest_u + DCT_offset + 8,
                                 DCT_stride);
                slice_intra_DCT (decoder, 2, dest_v + DCT_offset + 8,
                                 DCT_stride);
            }
        } else {

            motion_parser_t * parser;

            parser =
                decoder->motion_parser[macroblock_modes >> MOTION_TYPE_SHIFT];
            MOTION_CALL (parser, macroblock_modes);

            if (macroblock_modes & MACROBLOCK_PATTERN) {
                int coded_block_pattern;
                int DCT_offset, DCT_stride;

                if (macroblock_modes & DCT_TYPE_INTERLACED) {
                    DCT_offset = decoder->stride;
                    DCT_stride = decoder->stride * 2;
                } else {
                    DCT_offset = decoder->stride * 8;
                    DCT_stride = decoder->stride;
                }

                coded_block_pattern = get_coded_block_pattern (decoder);

                if (likely (decoder->chroma_format == 0)) {
                    int offset = decoder->offset;
                    uint8_t * dest_y = decoder->dest[0] + offset;
                    if (coded_block_pattern & 1)
                        slice_non_intra_DCT (decoder, 0, dest_y, DCT_stride);
                    if (coded_block_pattern & 2)
                        slice_non_intra_DCT (decoder, 0, dest_y + 8,
                                             DCT_stride);
                    if (coded_block_pattern & 4)
                        slice_non_intra_DCT (decoder, 0, dest_y + DCT_offset,
                                             DCT_stride);
                    if (coded_block_pattern & 8)
                        slice_non_intra_DCT (decoder, 0,
                                             dest_y + DCT_offset + 8,
                                             DCT_stride);
                    if (coded_block_pattern & 16)
                        slice_non_intra_DCT (decoder, 1,
                                             decoder->dest[1] + (offset >> 1),
                                             decoder->uv_stride);
                    if (coded_block_pattern & 32)
                        slice_non_intra_DCT (decoder, 2,
                                             decoder->dest[2] + (offset >> 1),
                                             decoder->uv_stride);
                } else if (likely (decoder->chroma_format == 1)) {
                    int offset;
                    uint8_t * dest_y;

                    coded_block_pattern |= bit_buf & (3 << 30);
                    DUMPBITS (bit_buf, bits, 2);

                    offset = decoder->offset;
                    dest_y = decoder->dest[0] + offset;
                    if (coded_block_pattern & 1)
                        slice_non_intra_DCT (decoder, 0, dest_y, DCT_stride);
                    if (coded_block_pattern & 2)
                        slice_non_intra_DCT (decoder, 0, dest_y + 8,
                                             DCT_stride);
                    if (coded_block_pattern & 4)
                        slice_non_intra_DCT (decoder, 0, dest_y + DCT_offset,
                                             DCT_stride);
                    if (coded_block_pattern & 8)
                        slice_non_intra_DCT (decoder, 0,
                                             dest_y + DCT_offset + 8,
                                             DCT_stride);

                    DCT_stride >>= 1;
                    DCT_offset = (DCT_offset + offset) >> 1;
                    if (coded_block_pattern & 16)
                        slice_non_intra_DCT (decoder, 1,
                                             decoder->dest[1] + (offset >> 1),
                                             DCT_stride);
                    if (coded_block_pattern & 32)
                        slice_non_intra_DCT (decoder, 2,
                                             decoder->dest[2] + (offset >> 1),
                                             DCT_stride);
                    if (coded_block_pattern & (2 << 30))
                        slice_non_intra_DCT (decoder, 1,
                                             decoder->dest[1] + DCT_offset,
                                             DCT_stride);
                    if (coded_block_pattern & (1 << 30))
                        slice_non_intra_DCT (decoder, 2,
                                             decoder->dest[2] + DCT_offset,
                                             DCT_stride);
                } else {
                    int offset;
                    uint8_t * dest_y, * dest_u, * dest_v;

                    coded_block_pattern |= bit_buf & (63 << 26);
                    DUMPBITS (bit_buf, bits, 6);

                    offset = decoder->offset;
                    dest_y = decoder->dest[0] + offset;
                    dest_u = decoder->dest[1] + offset;
                    dest_v = decoder->dest[2] + offset;

                    if (coded_block_pattern & 1)
                        slice_non_intra_DCT (decoder, 0, dest_y, DCT_stride);
                    if (coded_block_pattern & 2)
                        slice_non_intra_DCT (decoder, 0, dest_y + 8,
                                             DCT_stride);
                    if (coded_block_pattern & 4)
                        slice_non_intra_DCT (decoder, 0, dest_y + DCT_offset,
                                             DCT_stride);
                    if (coded_block_pattern & 8)
                        slice_non_intra_DCT (decoder, 0,
                                             dest_y + DCT_offset + 8,
                                             DCT_stride);

                    if (coded_block_pattern & 16)
                        slice_non_intra_DCT (decoder, 1, dest_u, DCT_stride);
                    if (coded_block_pattern & 32)
                        slice_non_intra_DCT (decoder, 2, dest_v, DCT_stride);
                    if (coded_block_pattern & (32 << 26))
                        slice_non_intra_DCT (decoder, 1, dest_u + DCT_offset,
                                             DCT_stride);
                    if (coded_block_pattern & (16 << 26))
                        slice_non_intra_DCT (decoder, 2, dest_v + DCT_offset,
                                             DCT_stride);
                    if (coded_block_pattern & (8 << 26))
                        slice_non_intra_DCT (decoder, 1, dest_u + 8,
                                             DCT_stride);
                    if (coded_block_pattern & (4 << 26))
                        slice_non_intra_DCT (decoder, 2, dest_v + 8,
                                             DCT_stride);
                    if (coded_block_pattern & (2 << 26))
                        slice_non_intra_DCT (decoder, 1,
                                             dest_u + DCT_offset + 8,
                                             DCT_stride);
                    if (coded_block_pattern & (1 << 26))
                        slice_non_intra_DCT (decoder, 2,
                                             dest_v + DCT_offset + 8,
                                             DCT_stride);
                }
            }

            decoder->dc_dct_pred[0] = decoder->dc_dct_pred[1] =
                decoder->dc_dct_pred[2] = 16384;
        }

        NEXT_MACROBLOCK;

        NEEDBITS (bit_buf, bits, bit_ptr);
        mba_inc = 0;
        while (1) {
            if (bit_buf >= 0x10000000) {
                mba = MBA_5 + (UBITS (bit_buf, 5) - 2);
                break;
            } else if (bit_buf >= 0x03000000) {
                mba = MBA_11 + (UBITS (bit_buf, 11) - 24);
                break;
            } else switch (UBITS (bit_buf, 11)) {
            case 8:             /* macroblock_escape */
                mba_inc += 33;
                /* pass through */
            case 15:    /* macroblock_stuffing (MPEG1 only) */
                DUMPBITS (bit_buf, bits, 11);
                NEEDBITS (bit_buf, bits, bit_ptr);
                continue;
            default:    /* end of slice, or error */
                if (mpeg2_cpu_state_restore)
                    mpeg2_cpu_state_restore (&cpu_state);
                return;
            }
        }
        DUMPBITS (bit_buf, bits, mba->len);
        mba_inc += mba->mba;

        if (mba_inc) {
            decoder->dc_dct_pred[0] = decoder->dc_dct_pred[1] =
                decoder->dc_dct_pred[2] = 16384;

            if (decoder->coding_type == P_TYPE) {
                do {
                    MOTION_CALL (decoder->motion_parser[0],
                                 MACROBLOCK_MOTION_FORWARD);
                    NEXT_MACROBLOCK;
                } while (--mba_inc);
            } else {
                do {
                    MOTION_CALL (decoder->motion_parser[4], macroblock_modes);
                    NEXT_MACROBLOCK;
                } while (--mba_inc);
            }
        }
    }
#undef bit_buf
#undef bits
#undef bit_ptr
}

---