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