parseblock.c

MPEG2 PLAYER in linux

/*
 * parseblock.c --
 *
 *      Procedures to read in the values of a block and store them
 *      in a place where the player can use them.
 *
 */

/*
 * Copyright (c) 1995 The Regents of the University of California.
 * All rights reserved.
 * 
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose, without fee, and without written agreement is
 * hereby granted, provided that the above copyright notice and the following
 * two paragraphs appear in all copies of this software.
 * 
 * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
 * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 */

/*
 * Portions of this software Copyright (c) 1995 Brown University.
 * All rights reserved.
 * 
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose, without fee, and without written agreement
 * is hereby granted, provided that the above copyright notice and the
 * following two paragraphs appear in all copies of this software.
 * 
 * IN NO EVENT SHALL BROWN UNIVERSITY BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF BROWN
 * UNIVERSITY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * BROWN UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
 * BASIS, AND BROWN UNIVERSITY HAS NO OBLIGATION TO PROVIDE MAINTENANCE,
 * SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 */

#define NO_SANITY_CHECKS
#include <assert.h>
#include "video.h"
#include "proto.h"
#include "decoders.h"


/*
   Changes to make the code reentrant:
      deglobalized: curBits, bitOffset, bitLength, bitBuffer, curVidStream,
      zigzag_direct now a const int variable initialized once
   [e-mail] (Loring Holden)
 */

/* External declarations. */
extern const int zigzag_direct[];
#ifdef DCPREC
extern int dcprec;
#endif

/* Macro for returning 1 if num is positive, -1 if negative, 0 if 0. */

#define Sign(num) ((num > 0) ? 1 : ((num == 0) ? 0 : -1))


/*
 *--------------------------------------------------------------
 *
 * ParseReconBlock --
 *
 *    Parse values for block structure from bitstream.
 *      n is an indication of the position of the block within
 *      the macroblock (i.e. 0-5) and indicates the type of 
 *      block (i.e. luminance or chrominance). Reconstructs
 *      coefficients from values parsed and puts in 
 *      block.dct_recon array in vid stream structure.
 *      sparseFlag is set when the block contains only one
 *      coeffictient and is used by the IDCT.
 *
 * Results:
 *    
 *
 * Side effects:
 *      Bit stream irreversibly parsed.
 *
 *--------------------------------------------------------------
 */

#define DCT_recon blockPtr->dct_recon
#define DCT_dc_y_past blockPtr->dct_dc_y_past
#define DCT_dc_cr_past blockPtr->dct_dc_cr_past
#define DCT_dc_cb_past blockPtr->dct_dc_cb_past

#define DECODE_DCT_COEFF_FIRST DecodeDCTCoeffFirst
#define DECODE_DCT_COEFF_NEXT DecodeDCTCoeffNext

void
ParseReconBlock(n, vid_stream)
     int n;
     VidStream *vid_stream;
{
#ifdef RISC
  unsigned int temp_curBits;
  int temp_bitOffset;
  int temp_bufLength;
  unsigned int *temp_bitBuffer;
#endif

  Block *blockPtr = &vid_stream->block;
  int coeffCount=0;
  
  if (vid_stream->buf_length < 100)
    correct_underflow(vid_stream);

#ifdef RISC
  temp_curBits = vid_stream->curBits;
  temp_bitOffset = vid_stream->buf_offset;
  temp_bufLength = vid_stream->buf_length;
  temp_bitBuffer = bitBuffer;
#endif

  {
    /*
     * Copy the VidStream fields curBits, bitOffset, and bitBuffer
     * into local variables with the same names, so the macros use the
     * local variables instead.  This allows register allocation and
     * can provide 1-2 fps speedup.  On machines with not so many registers,
     * don't do this.
     */
#ifdef RISC
    register unsigned int curBits = temp_curBits;
    register int bitOffset = temp_bitOffset;
    register int bufLength = temp_bufLength;
    register unsigned int *bitBuffer = temp_bitBuffer;
#endif

    int diff;
    int size, level=0, i, run, pos, coeff;
    short int *reconptr;
    unsigned char *iqmatrixptr, *niqmatrixptr;
    int qscale;

    reconptr = DCT_recon[0];

    /* 
     * Hand coded version of memset that's a little faster...
     * Old call:
     *    memset((char *) DCT_recon, 0, 64*sizeof(short int));
     */
    {
      INT32 *p;
      p = (INT32 *) reconptr;

      p[0] = p[1] = p[2] = p[3] = p[4] = p[5] = p[6] = p[7] = p[8] = p[9] = 
      p[10] = p[11] = p[12] = p[13] = p[14] = p[15] = p[16] = p[17] = p[18] =
      p[19] = p[20] = p[21] = p[22] = p[23] = p[24] = p[25] = p[26] = p[27] =
      p[28] = p[29] = p[30] = p[31] = 0;

    }

    if (vid_stream->mblock.mb_intra) {

      if (n < 4) {

    /*
     * Get the luminance bits.  This code has been hand optimized to
     * get by the normal bit parsing routines.  We get some speedup
     * by grabbing the next 16 bits and parsing things locally.
     * Thus, calls are translated as:
     *
     *    show_bitsX  <-->   next16bits >> (16-X)
     *    get_bitsX   <-->   val = next16bits >> (16-flushed-X);
     *               flushed += X;
     *               next16bits &= bitMask[flushed];
     *    flush_bitsX <-->   flushed += X;
     *               next16bits &= bitMask[flushed];
     *
     * I've streamlined the code a lot, so that we don't have to mask
     * out the low order bits and a few of the extra adds are removed.
     *    bsmith
     */
    unsigned int next16bits, index, flushed;

        show_bits16(next16bits);
        index = next16bits >> (16-5);
        if (index < 31) {
          size = dct_dc_size_luminance[index].value;
          flushed = dct_dc_size_luminance[index].num_bits;
        } else {
          index = next16bits >> (16-9);
          index -= 0x1f0;
          size = dct_dc_size_luminance1[index].value;
          flushed = dct_dc_size_luminance1[index].num_bits;
        }
        next16bits &= bitMask[16+flushed];

        if (size != 0) {
          flushed += size;
          diff = next16bits >> (16-flushed);
          if (!(diff & bitTest[32-size])) {
            diff = rBitMask[size] | (diff + 1);
          }
        } else {
          diff = 0;
        }
        flush_bits(flushed);

        if (n == 0) {
          coeff = diff << 3;
          if (vid_stream->mblock.mb_address -
              vid_stream->mblock.past_intra_addr > 1) {
            coeff += 1024;
          } else {
		    coeff += DCT_dc_y_past;
          }
          DCT_dc_y_past = coeff;
        } else {
          coeff = DCT_dc_y_past + (diff << 3);
          DCT_dc_y_past = coeff;
        }

      } else { /* n = 4 or 5 */
    
    /*
     * Get the chrominance bits.  This code has been hand optimized to
     * as described above
     */

    unsigned int next16bits, index, flushed;

        show_bits16(next16bits);
        index = next16bits >> (16-5);
        if (index < 31) {
          size = dct_dc_size_chrominance[index].value;
          flushed = dct_dc_size_chrominance[index].num_bits;
        } else {
          index = next16bits >> (16-10);
          index -= 0x3e0;
          size = dct_dc_size_chrominance1[index].value;
          flushed = dct_dc_size_chrominance1[index].num_bits;
        }
        next16bits &= bitMask[16+flushed];
    
        if (size != 0) {
          flushed += size;
          diff = next16bits >> (16-flushed);
          if (!(diff & bitTest[32-size])) {
            diff = rBitMask[size] | (diff + 1);
          }
        } else {
          diff = 0;
        }
        flush_bits(flushed);
    
      /* We test 5 first; a result of the mixup of Cr and Cb */
        if (n == 5) {
          coeff = diff << 3;

          if (vid_stream->mblock.mb_address -
              vid_stream->mblock.past_intra_addr > 1) {
            coeff += 1024;
          } else {
            coeff += DCT_dc_cr_past;
          }
          DCT_dc_cr_past = coeff;
        } else {
          coeff = diff << 3;
          if (vid_stream->mblock.mb_address -
              vid_stream->mblock.past_intra_addr > 1) {
            coeff += 1024;
          } else {
            coeff += DCT_dc_cb_past;
          }
          DCT_dc_cb_past = coeff;
        }
      }
      
      *reconptr = coeff;
      i = 0; 
      pos = 0;
      coeffCount = (coeff != 0);
    
      if (vid_stream->picture.code_type != 4) {
    
        qscale = vid_stream->slice.quant_scale;
        iqmatrixptr = vid_stream->intra_quant_matrix[0];
    
        while(1) {
      
          DECODE_DCT_COEFF_NEXT(run, level);

          if (run >= END_OF_BLOCK) break;

          i = i + run + 1;
          pos = zigzag_direct[i];

          /* quantizes and oddifies each coefficient */
          if (level < 0) {
            coeff = ((level<<1) * qscale * 
                     ((int) (iqmatrixptr[pos]))) / 16; 
            coeff += (1 - (coeff & 1));
          } else {
            coeff = ((level<<1) * qscale * 
                     ((int) (*(iqmatrixptr+pos)))) >> 4; 
            coeff -= (1 - (coeff & 1));
          }
#ifdef QUANT_CHECK
          printf ("coeff: %d\n", coeff);
#endif

          reconptr[pos] = coeff;
          coeffCount++;

        }

#ifdef QUANT_CHECK
		printf ("\n");
#endif

#ifdef ANALYSIS 
        {
          extern unsigned int *mbCoeffPtr;
          mbCoeffPtr[pos]++;
        }
#endif

        flush_bits(2);
		goto end;
      }
    } else { /* non-intra-coded macroblock */
      
      niqmatrixptr = vid_stream->non_intra_quant_matrix[0];
      qscale = vid_stream->slice.quant_scale;
      
      DECODE_DCT_COEFF_FIRST(run, level);
      i = run;

      pos = zigzag_direct[i];

        /* quantizes and oddifies each coefficient */
      if (level < 0) {
        coeff = (((level<<1) - 1) * qscale * 
                 ((int) (niqmatrixptr[pos]))) / 16; 
	if ((coeff & 1) == 0) {coeff = coeff + 1;}
      } else {
        coeff = (((level<<1) + 1) * qscale * 
                 ((int) (*(niqmatrixptr+pos)))) >> 4; 
	coeff = (coeff-1) | 1; /* equivalent to: if ((coeff&1)==0) coeff = coeff - 1; */
      }

      reconptr[pos] = coeff;
      if (coeff) {
          coeffCount = 1;
      }

      if (vid_stream->picture.code_type != 4) {
    
        while(1) {
      
          DECODE_DCT_COEFF_NEXT(run, level);

          if (run >= END_OF_BLOCK) {
	       	break;
          }

          i = i+run+1;
          pos = zigzag_direct[i];
          if (level < 0) {
            coeff = (((level<<1) - 1) * qscale * 
                     ((int) (niqmatrixptr[pos]))) / 16; 
            if ((coeff & 1) == 0) {coeff = coeff + 1;}
          } else {
            coeff = (((level<<1) + 1) * qscale * 
                     ((int) (*(niqmatrixptr+pos)))) >> 4; 
            coeff = (coeff-1) | 1; /* equivalent to: if ((coeff&1)==0) coeff = coeff - 1; */
          }
          reconptr[pos] = coeff;
          coeffCount++;
        } /* end while */

#ifdef ANALYSIS
        {
          extern unsigned int *mbCoeffPtr;
          mbCoeffPtr[pos]++;
        }
#endif

        flush_bits(2);

        goto end;
      } /* end if (vid_stream->picture.code_type != 4) */
    }
    
  end:

    if (coeffCount == 1) {
      j_rev_dct_sparse (reconptr, pos);
    }
    else {
#ifdef FLOATDCT
      if (qualityFlag) {
     	float_idct(reconptr);
      } else {
#endif
        j_rev_dct(reconptr);
#ifdef FLOATDCT
      }
#endif
    }

#ifdef RISC
    temp_curBits = vid_stream->curBits;
    temp_bitOffset = vid_stream->bit_offset;
    temp_bufLength = vid_stream->buf_length;
    temp_bitBuffer = bitBuffer;
#endif

  }

#ifdef RISC
  vid_stream->curBits = temp_curBits;
  vid_stream->bitOffset = temp_bitOffset;
  vid_stream->buf_length = temp_bufLength;
  bitBuffer = temp_bitBuffer;
#endif
}
    
#undef DCT_recon 
#undef DCT_dc_y_past 
#undef DCT_dc_cr_past 
#undef DCT_dc_cb_past 


/*
 *--------------------------------------------------------------
 *
 * ParseAwayBlock --
 *
 *    Parses off block values, throwing them away.
 *      Used with grayscale dithering.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *      None.
 *
 *--------------------------------------------------------------
 */

void
ParseAwayBlock(n, vid_stream)
     int n;
     VidStream *vid_stream;
{
  unsigned int diff;
  unsigned int size, run;
  int level;

  if (vid_stream->buf_length < 100)
    correct_underflow(vid_stream);

  if (vid_stream->mblock.mb_intra) {

    /* If the block is a luminance block... */

    if (n < 4) {

      /* Parse and decode size of first coefficient. */

      DecodeDCTDCSizeLum(size);

      /* Parse first coefficient. */

      if (size != 0) {
        get_bitsn(size, diff);
      }
    }

    /* Otherwise, block is chrominance block... */

    else {

      /* Parse and decode size of first coefficient. */

      DecodeDCTDCSizeChrom(size);

      /* Parse first coefficient. */

      if (size != 0) {
        get_bitsn(size, diff);
      }
    }
  }

  /* Otherwise, block is not intracoded... */

  else {

    /* Decode and set first coefficient. */

    DECODE_DCT_COEFF_FIRST(run, level);
  }

  /* If picture is not D type (i.e. I, P, or B)... */

  if (vid_stream->picture.code_type != 4) {

    /* While end of macroblock has not been reached... */

    while (1) {

      /* Get the dct_coeff_next */

      DECODE_DCT_COEFF_NEXT(run, level);

      if (run >= END_OF_BLOCK) break;
    }

    /* End_of_block */

    flush_bits(2);
  }
}