jchuff.c

基于Linux的ffmepg decoder

/*
 * jchuff.c
 *
 * Copyright (C) 1991-1997, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains Huffman entropy encoding routines.
 *
 * Much of the complexity here has to do with supporting output suspension.
 * If the data destination module demands suspension, we want to be able to
 * back up to the start of the current MCU.  To do this, we copy state
 * variables into local working storage, and update them back to the
 * permanent JPEG objects only upon successful completion of an MCU.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jchuff.h"		/* Declarations shared with jcphuff.c */
#include "huftbl_new.h"
#include "huftbl_default.h"


/* Expanded entropy encoder object for Huffman encoding.
 *
 * The savable_state subrecord contains fields that change within an MCU,
 * but must not be updated permanently until we complete the MCU.
 */

typedef struct {
  INT32 put_buffer;		/* current bit-accumulation buffer */
  int put_bits;			/* # of bits now in it */
  int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
} savable_state;

/* This macro is to work around compilers with missing or broken
 * structure assignment.  You'll need to fix this code if you have
 * such a compiler and you change MAX_COMPS_IN_SCAN.
 */
#if 0

#ifndef NO_STRUCT_ASSIGN
#define ASSIGN_STATE(dest,src)  ((dest) = (src))
#else
#if MAX_COMPS_IN_SCAN == 4
#define ASSIGN_STATE(dest,src)  \
	((dest).put_buffer = (src).put_buffer, \
	 (dest).put_bits = (src).put_bits, \
	 (dest).last_dc_val[0] = (src).last_dc_val[0], \
	 (dest).last_dc_val[1] = (src).last_dc_val[1], \
	 (dest).last_dc_val[2] = (src).last_dc_val[2], \
	 (dest).last_dc_val[3] = (src).last_dc_val[3])
#endif
#endif

#endif

typedef struct {
  struct jpeg_entropy_encoder pub; /* public fields */

  savable_state saved;		/* Bit buffer & DC state at start of MCU */

  /* These fields are NOT loaded into local working state. */
  unsigned int restarts_to_go;	/* MCUs left in this restart interval */
  int next_restart_num;		/* next restart number to write (0-7) */

  /* Pointers to derived tables (these workspaces have image lifespan) */
  c_derived_tbl * dc_derived_tbls[NUM_HUFF_TBLS];
  c_derived_tbl * ac_derived_tbls[NUM_HUFF_TBLS];

#ifdef ENTROPY_OPT_SUPPORTED	/* Statistics tables for optimization */
  long * dc_count_ptrs[NUM_HUFF_TBLS];
  long * ac_count_ptrs[NUM_HUFF_TBLS];
#endif
} huff_entropy_encoder;

typedef huff_entropy_encoder * huff_entropy_ptr;

/* Working state while writing an MCU.
 * This struct contains all the fields that are needed by subroutines.
 */

typedef struct {
  JOCTET * next_output_byte;	/* => next byte to write in buffer */
  unsigned int * next_output_word;		//pwhsu++:20040113
  size_t free_in_buffer;	/* # of byte spaces remaining in buffer */
  savable_state cur;		/* Current bit buffer & DC state */
  j_compress_ptr cinfo;		/* dump_buffer needs access to this */
} working_state;


/* Forward declarations */
//METHODDEF(boolean) encode_mcu_huff JPP((j_compress_ptr cinfo,
//					JBLOCKROW *MCU_data));
METHODDEF(void) finish_pass_huff JPP((j_compress_ptr cinfo));
//#ifdef ENTROPY_OPT_SUPPORTED
//METHODDEF(boolean) encode_mcu_gather JPP((j_compress_ptr cinfo,
//					  JBLOCKROW *MCU_data));
//METHODDEF(void) finish_pass_gather JPP((j_compress_ptr cinfo));


//METHODDEF(void) Encode_block JPP((working_state * state, int last_dc_val, 
//							 int dc_tbln, int ac_tbln, int vlcnum));
//#endif


/*
 * Initialize for a Huffman-compressed scan.
 * If gather_statistics is TRUE, we do not output anything during the scan,
 * just count the Huffman symbols used and generate Huffman code tables.
 */
#if 0
METHODDEF(void)
start_pass_huff (j_compress_ptr cinfo, boolean gather_statistics)
{
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
  int ci, dctbl, actbl;
  jpeg_component_info * compptr;

//  entropy->pub.encode_mcu = encode_mcu_huff;
  entropy->pub.finish_pass = finish_pass_huff;


  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
    compptr = cinfo->cur_comp_info[ci];
    dctbl = compptr->dc_tbl_no;
    actbl = compptr->ac_tbl_no;

    /* Compute derived values for Huffman tables */
    /* We may do this more than once for a table, but it's not expensive */
    jpeg_make_c_derived_tbl(cinfo, TRUE, dctbl,
			      & entropy->dc_derived_tbls[dctbl]);		//pwhsu:20031016 玻ネdc huffman table 
    jpeg_make_c_derived_tbl(cinfo, FALSE, actbl,
			      & entropy->ac_derived_tbls[actbl]);		//pwhsu:20031016 玻ネac huffman table
	
  }

  /* Initialize restart stuff */
  entropy->restarts_to_go = cinfo->restart_interval;
  entropy->next_restart_num = 0;
}
#endif



void start_pass_huff1 (j_compress_ptr cinfo)
{
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
  //int ci, dctbl, actbl; 
  //jpeg_component_info * compptr;
  unsigned int *curtbl;
  int i;

  entropy->pub.finish_pass = finish_pass_huff;
#if 0
  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
    compptr = cinfo->cur_comp_info[ci];
    dctbl = compptr->dc_tbl_no;
    actbl = compptr->ac_tbl_no;

    /* Compute derived values for Huffman tables */
    /* We may do this more than once for a table, but it's not expensive */
    jpeg_make_c_derived_tbl(cinfo, TRUE, dctbl,
			      & entropy->dc_derived_tbls[dctbl]);		//pwhsu:20031016 玻ネdc huffman table 
    jpeg_make_c_derived_tbl(cinfo, FALSE, actbl,
			      & entropy->ac_derived_tbls[actbl]);		//pwhsu:20031016 玻ネac huffman table
	
  }
#else
  if(hufftbl_no==1){	//default table
	  //dc 0 huffman table
	  curtbl = huftbl0_dc;
	  //__asm{
		  //STR	dchuftbl0[0], [curtbl]
		  //STR	dchuftbl0[1], [curtbl+1]
		  //STR	dchuftbl0[2], [curtbl+2]
		  //STR	dchuftbl0[3], [curtbl+3]
		  //STR	dchuftbl0[4], [curtbl+4]
		  //STR	dchuftbl0[5], [curtbl+5]
		  //STR	dchuftbl0[6], [curtbl+6]
		  //STR	dchuftbl0[7], [curtbl+7]
		  //STR	dchuftbl0[8], [curtbl+8]
		  //STR	dchuftbl0[9], [curtbl+9]
		  //STR	dchuftbl0[10], [curtbl+10]
		  //STR	dchuftbl0[11], [curtbl+11]
		  //STR	dchuftbl0[12], [curtbl+12]
		  //STR	dchuftbl0[13], [curtbl+13]
		  //STR	dchuftbl0[14], [curtbl+14]
	  //}
	      curtbl[0]=dchuftbl0[0];
	      curtbl[1]=dchuftbl0[1];
	      curtbl[2]=dchuftbl0[2];
	      curtbl[3]=dchuftbl0[3];
	      curtbl[4]=dchuftbl0[4];
	      curtbl[5]=dchuftbl0[5];
	      curtbl[6]=dchuftbl0[6];
	      curtbl[7]=dchuftbl0[7];
	      curtbl[8]=dchuftbl0[8];
	      curtbl[9]=dchuftbl0[9];
	      curtbl[10]=dchuftbl0[10];
	      curtbl[11]=dchuftbl0[11];
	      curtbl[12]=dchuftbl0[12];
	      curtbl[13]=dchuftbl0[13];
	      curtbl[14]=dchuftbl0[14];

	  //dc 1 huffman table
	  curtbl = huftbl1_dc;	  
	  //__asm{
		  //STR	dchuftbl1[0], [curtbl+0]
		  //STR	dchuftbl1[1], [curtbl+1]
		  //STR	dchuftbl1[2], [curtbl+2]
		  //STR	dchuftbl1[3], [curtbl+3]
		  //STR	dchuftbl1[4], [curtbl+4]
		  //STR	dchuftbl1[5], [curtbl+5]
		  //STR	dchuftbl1[6], [curtbl+6]
		  //STR	dchuftbl1[7], [curtbl+7]
		  //STR	dchuftbl1[8], [curtbl+8]
		  //STR	dchuftbl1[9], [curtbl+9]
		  //STR	dchuftbl1[10], [curtbl+10]
		  //STR	dchuftbl1[11], [curtbl+11]
		  //STR	dchuftbl1[12], [curtbl+12]
		  //STR	dchuftbl1[13], [curtbl+13]
		  //STR	dchuftbl1[14], [curtbl+14]
	  //}
	      curtbl[0]=dchuftbl1[0];
	      curtbl[1]=dchuftbl1[1];
	      curtbl[2]=dchuftbl1[2];
	      curtbl[3]=dchuftbl1[3];
	      curtbl[4]=dchuftbl1[4];
	      curtbl[5]=dchuftbl1[5];
	      curtbl[6]=dchuftbl1[6];
	      curtbl[7]=dchuftbl1[7];
	      curtbl[8]=dchuftbl1[8];
	      curtbl[9]=dchuftbl1[9];
	      curtbl[10]=dchuftbl1[10];
	      curtbl[11]=dchuftbl1[11];
	      curtbl[12]=dchuftbl1[12];
	      curtbl[13]=dchuftbl1[13];
	      curtbl[14]=dchuftbl1[14];
	  //ac 0 huffman table
	  curtbl = huftbl0_ac;
	  for(i=0;i<256;i++){
		  //__asm{
			  //STR	achuftbl0[i], [curtbl+i]
		  //}
		  curtbl[i]=achuftbl0[i];
	  }
	  //ac 1 huffman table
	  curtbl = huftbl1_ac;
	  for(i=0;i<256;i++){
		  //__asm{
			  //STR	achuftbl1[i], [curtbl+i]
		  //}
		  curtbl[i]=achuftbl1[i];
	  }  

  }else{	//new table
	  //dc 0 huffman table
	  curtbl = huftbl0_dc;
	  for(i=0;i<15;i++){
		  //__asm{
			  //STR	dchuftbln0[i], [curtbl+i]
		  //}
		  curtbl[i]=dchuftbln0[i];
	  }
	  //dc 1 huffman table
	  curtbl = huftbl1_dc;
	  for(i=0;i<15;i++){
		  //__asm{
			  //STR	dchuftbln1[i], [curtbl+i]
		  //}
		  curtbl[i]=dchuftbln1[i];
	  }
	  //ac 0 huffman table
	  curtbl = huftbl0_ac;
	  for(i=0;i<256;i++){
		  //__asm{
			  //STR	achuftbln0[i], [curtbl+i]
		  //}
		  curtbl[i]=achuftbln0[i];
	  }
	  //ac 1 huffman table
	  curtbl = huftbl1_ac;
	  for(i=0;i<256;i++){
		  //__asm{
			  //STR	achuftbln1[i], [curtbl+i]
		  //}
		  curtbl[i]=achuftbln1[i];
	  }  
  }

#endif

  /* Initialize restart stuff */
  entropy->restarts_to_go = cinfo->restart_interval;
  entropy->next_restart_num = 0;
}




/*
 * Compute the derived values for a Huffman table.