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slice.cpp

/*
 * 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, 2);    /* 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, 4);    /* 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, 2);    /* 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, 2);    /* 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, 2);    /* 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 >> 1),                \
            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
}

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