| /* |
| * 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[])); |
