src/jpeg/jchuff.h

/*
 * jchuff.h
 *
 * 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 declarations for Huffman entropy encoding routines
 * that are shared between the sequential encoder (jchuff.c) and the
 * progressive encoder (jcphuff.c).  No other modules need to see these.
 */

/* The legal range of a DCT coefficient is
 *  -1024 .. +1023  for 8-bit data;
 * -16384 .. +16383 for 12-bit data.
 * Hence the magnitude should always fit in 10 or 14 bits respectively.
 */

#if BITS_IN_JSAMPLE == 8
#define MAX_COEF_BITS 10
#else
#define MAX_COEF_BITS 14
#endif

/* Derived data constructed for each Huffman table */

typedef struct {
  unsigned int ehufco[256];	/* code for each symbol */
  char ehufsi[256];		/* length of code for each symbol */
  /* If no code has been allocated for a symbol S, ehufsi[S] contains 0 */
} c_derived_tbl;

/* Short forms of external names for systems with brain-damaged linkers. */

#ifdef NEED_SHORT_EXTERNAL_NAMES
#define jpeg_make_c_derived_tbl	jMkCDerived
#define jpeg_gen_optimal_table	jGenOptTbl
#endif /* NEED_SHORT_EXTERNAL_NAMES */

/* Expand a Huffman table definition into the derived format */
EXTERN(void) jpeg_make_c_derived_tbl
	JPP((j_compress_ptr cinfo, boolean isDC, int tblno,
	     c_derived_tbl ** pdtbl));

/* Generate an optimal table definition given the specified counts */
EXTERN(void) jpeg_gen_optimal_table
	JPP((j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[]));
Commit	Line	Data
	1	/*
	2	* jchuff.h
	3	*
	4	* Copyright (C) 1991-1997, Thomas G. Lane.
	5	* This file is part of the Independent JPEG Group's software.
	6	* For conditions of distribution and use, see the accompanying README file.
	7	*
	8	* This file contains declarations for Huffman entropy encoding routines
	9	* that are shared between the sequential encoder (jchuff.c) and the
	10	* progressive encoder (jcphuff.c). No other modules need to see these.
	11	*/
	12
	13	/* The legal range of a DCT coefficient is
	14	* -1024 .. +1023 for 8-bit data;
	15	* -16384 .. +16383 for 12-bit data.
	16	* Hence the magnitude should always fit in 10 or 14 bits respectively.
	17	*/
	18
	19	#if BITS_IN_JSAMPLE == 8
	20	#define MAX_COEF_BITS 10
	21	#else
	22	#define MAX_COEF_BITS 14
	23	#endif
	24
	25	/* Derived data constructed for each Huffman table */
	26
	27	typedef struct {
	28	unsigned int ehufco[256]; /* code for each symbol */
	29	char ehufsi[256]; /* length of code for each symbol */
	30	/* If no code has been allocated for a symbol S, ehufsi[S] contains 0 */
	31	} c_derived_tbl;
	32
	33	/* Short forms of external names for systems with brain-damaged linkers. */
	34
	35	#ifdef NEED_SHORT_EXTERNAL_NAMES
	36	#define jpeg_make_c_derived_tbl jMkCDerived
	37	#define jpeg_gen_optimal_table jGenOptTbl
	38	#endif /* NEED_SHORT_EXTERNAL_NAMES */
	39
	40	/* Expand a Huffman table definition into the derived format */
	41	EXTERN(void) jpeg_make_c_derived_tbl
	42	JPP((j_compress_ptr cinfo, boolean isDC, int tblno,
	43	c_derived_tbl ** pdtbl));
	44
	45	/* Generate an optimal table definition given the specified counts */
	46	EXTERN(void) jpeg_gen_optimal_table
	47	JPP((j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[]));