1/*
2 * reserved comment block
3 * DO NOT REMOVE OR ALTER!
4 */
5/*
6 * jchuff.h
7 *
8 * Copyright (C) 1991-1997, Thomas G. Lane.
9 * This file is part of the Independent JPEG Group's software.
10 * For conditions of distribution and use, see the accompanying README file.
11 *
12 * This file contains declarations for Huffman entropy encoding routines
13 * that are shared between the sequential encoder (jchuff.c) and the
14 * progressive encoder (jcphuff.c). No other modules need to see these.
15 */
16
17/* The legal range of a DCT coefficient is
18 * -1024 .. +1023 for 8-bit data;
19 * -16384 .. +16383 for 12-bit data.
20 * Hence the magnitude should always fit in 10 or 14 bits respectively.
21 */
22
23#if BITS_IN_JSAMPLE == 8
24#define MAX_COEF_BITS 10
25#else
26#define MAX_COEF_BITS 14
27#endif
28
29/* Derived data constructed for each Huffman table */
30
31typedef struct {
32 unsigned int ehufco[256]; /* code for each symbol */
33 char ehufsi[256]; /* length of code for each symbol */
34 /* If no code has been allocated for a symbol S, ehufsi[S] contains 0 */
35} c_derived_tbl;
36
37/* Short forms of external names for systems with brain-damaged linkers. */
38
39#ifdef NEED_SHORT_EXTERNAL_NAMES
40#define jpeg_make_c_derived_tbl jMkCDerived
41#define jpeg_gen_optimal_table jGenOptTbl
42#endif /* NEED_SHORT_EXTERNAL_NAMES */
43
44/* Expand a Huffman table definition into the derived format */
45EXTERN(void) jpeg_make_c_derived_tbl
46 JPP((j_compress_ptr cinfo, boolean isDC, int tblno,
47 c_derived_tbl ** pdtbl));
48
49/* Generate an optimal table definition given the specified counts */
50EXTERN(void) jpeg_gen_optimal_table
51 JPP((j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[]));
52