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