/*
 * Copyright (c) 1992 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.
 */
#define NO_SANITY_CHECKS
#include <config.h>
#include <assert.h>
#include "video.h"
#include "proto.h"
#include "decoders.h"
#include "my_dmalloc.h"

/* External declarations. */

extern int zigzag_direct[];

/* 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)
     int n;
{
#ifdef RISC
  unsigned int temp_curBits;
  int temp_bitOffset;
  int temp_bufLength;
  unsigned int *temp_bitBuffer;
#endif

  Block *blockPtr = &curVidStream->block;
  int coeffCount;
  
  if (bufLength < 100)
    correct_underflow();

#ifdef RISC
  temp_curBits = curBits;
  temp_bitOffset = bitOffset;
  temp_bufLength = bufLength;
  temp_bitBuffer = bitBuffer;
#endif

  {
    /*
     * Copy the globals curBits, bitOffset, bufLength, 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, 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 (curVidStream->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 >> (16-7);
	size = dct_dc_size_luminance[index].value;
	flushed = dct_dc_size_luminance[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 (curVidStream->mblock.mb_address -
	      curVidStream->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 {
	
	/*
	 * Get the chrominance bits.  This code has been hand optimized to
	 * as described above
	 */
	unsigned int next16bits, index, flushed;

	show_bits16(next16bits);
	index = next16bits >> (16-8);
	size = dct_dc_size_chrominance[index].value;
	flushed = dct_dc_size_chrominance[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 == 4) {
	  coeff = diff << 3;
	  if (curVidStream->mblock.mb_address -
	      curVidStream->mblock.past_intra_addr > 1) 
	    coeff += 1024;
	  else coeff += DCT_dc_cr_past;
	  DCT_dc_cr_past = coeff;

	} else {
	  coeff = diff << 3;
	  if (curVidStream->mblock.mb_address -
	      curVidStream->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 (curVidStream->picture.code_type != 4) {
	
	qscale = curVidStream->slice.quant_scale;
	iqmatrixptr = curVidStream->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];
	  coeff = (level * qscale * ((int) iqmatrixptr[pos])) >> 3;
	  if (level < 0) {
	      coeff += (coeff & 1);
	  } else {
	      coeff -= (coeff & 1);
	  }

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

	}

	flush_bits(2);

	goto end;
      }
    }
    
    else {
      
      niqmatrixptr = curVidStream->non_intra_quant_matrix[0];
      qscale = curVidStream->slice.quant_scale;
      
      DECODE_DCT_COEFF_FIRST(run, level);
      i = run;

      pos = zigzag_direct[i];
      if (level < 0) {
	  coeff = (((level<<1) - 1) * qscale * 
		   ((int) (niqmatrixptr[pos]))) >> 4; 
	  coeff += (coeff & 1);
      } else {
	  coeff = (((level<<1) + 1) * qscale * 
		   ((int) (*(niqmatrixptr+pos)))) >> 4; 
	  coeff -= (coeff & 1);
      }
      reconptr[pos] = coeff;
      if (coeff) {
	coeffCount = 1;
      }

      if (curVidStream->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]))) >> 4; 
	      coeff += (coeff & 1);
	  } else {
	      coeff = (((level<<1) + 1) * qscale * 
		       ((int) (*(niqmatrixptr+pos)))) >> 4; 
	      coeff -= (coeff & 1);
	  }
	  reconptr[pos] = coeff;
	  if (coeff) {
	    coeffCount++;
	  }
	}

	flush_bits(2);

	goto end;
      }
    }
    
  end:

    if (coeffCount == 1) mpeg_j_rev_dct_sparse (reconptr, pos);
    else mpeg_j_rev_dct(reconptr);

#ifdef RISC
    temp_curBits = curBits;
    temp_bitOffset = bitOffset;
    temp_bufLength = bufLength;
    temp_bitBuffer = bitBuffer;
#endif

  }

#ifdef RISC
  curBits = temp_curBits;
  bitOffset = temp_bitOffset;
  bufLength = 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)
     int n;
{
  unsigned int diff;
  unsigned int size, run;
  int level;

  if (bufLength < 100)
    correct_underflow();

  if (curVidStream->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 (curVidStream->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);
  }
}
