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jchuff.h
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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[]));
jpeg_make_c_derived_tbl
jpeg_make_c_derived_tbl(j_compress_ptr cinfo, boolean isDC, int tblno, c_derived_tbl **pdtbl)
Definition jchuff.cpp:179
EXTERN
EXTERN(void) jpeg_make_c_derived_tbl JPP((j_compress_ptr cinfo
pdtbl
boolean int c_derived_tbl ** pdtbl
Definition jchuff.h:43
isDC
boolean isDC
Definition jchuff.h:42
freq
JHUFF_TBL long freq[]
Definition jchuff.h:47
tblno
boolean int tblno
Definition jchuff.h:42
htbl
JHUFF_TBL * htbl
Definition jchuff.h:47
JPP
#define JPP(arglist)
Definition jpeglib.h:818
j_compress_ptr
struct jpeg_compress_struct * j_compress_ptr
Definition jpeglib.h:262
JHUFF_TBL
Definition jpeglib.h:100
c_derived_tbl
Definition jchuff.h:27
c_derived_tbl::ehufco
unsigned int ehufco[256]
Definition jchuff.h:28
c_derived_tbl::ehufsi
char ehufsi[256]
Definition jchuff.h:29