17dd7cddfSDavid du Colombier /* 27dd7cddfSDavid du Colombier * jchuff.h 37dd7cddfSDavid du Colombier * 4*593dc095SDavid du Colombier * Copyright (C) 1991-1997, Thomas G. Lane. 57dd7cddfSDavid du Colombier * This file is part of the Independent JPEG Group's software. 67dd7cddfSDavid du Colombier * For conditions of distribution and use, see the accompanying README file. 77dd7cddfSDavid du Colombier * 87dd7cddfSDavid du Colombier * This file contains declarations for Huffman entropy encoding routines 97dd7cddfSDavid du Colombier * that are shared between the sequential encoder (jchuff.c) and the 107dd7cddfSDavid du Colombier * progressive encoder (jcphuff.c). No other modules need to see these. 117dd7cddfSDavid du Colombier */ 127dd7cddfSDavid du Colombier 13*593dc095SDavid du Colombier /* The legal range of a DCT coefficient is 14*593dc095SDavid du Colombier * -1024 .. +1023 for 8-bit data; 15*593dc095SDavid du Colombier * -16384 .. +16383 for 12-bit data. 16*593dc095SDavid du Colombier * Hence the magnitude should always fit in 10 or 14 bits respectively. 17*593dc095SDavid du Colombier */ 18*593dc095SDavid du Colombier 19*593dc095SDavid du Colombier #if BITS_IN_JSAMPLE == 8 20*593dc095SDavid du Colombier #define MAX_COEF_BITS 10 21*593dc095SDavid du Colombier #else 22*593dc095SDavid du Colombier #define MAX_COEF_BITS 14 23*593dc095SDavid du Colombier #endif 24*593dc095SDavid du Colombier 257dd7cddfSDavid du Colombier /* Derived data constructed for each Huffman table */ 267dd7cddfSDavid du Colombier 277dd7cddfSDavid du Colombier typedef struct { 287dd7cddfSDavid du Colombier unsigned int ehufco[256]; /* code for each symbol */ 297dd7cddfSDavid du Colombier char ehufsi[256]; /* length of code for each symbol */ 307dd7cddfSDavid du Colombier /* If no code has been allocated for a symbol S, ehufsi[S] contains 0 */ 317dd7cddfSDavid du Colombier } c_derived_tbl; 327dd7cddfSDavid du Colombier 337dd7cddfSDavid du Colombier /* Short forms of external names for systems with brain-damaged linkers. */ 347dd7cddfSDavid du Colombier 357dd7cddfSDavid du Colombier #ifdef NEED_SHORT_EXTERNAL_NAMES 367dd7cddfSDavid du Colombier #define jpeg_make_c_derived_tbl jMkCDerived 377dd7cddfSDavid du Colombier #define jpeg_gen_optimal_table jGenOptTbl 387dd7cddfSDavid du Colombier #endif /* NEED_SHORT_EXTERNAL_NAMES */ 397dd7cddfSDavid du Colombier 407dd7cddfSDavid du Colombier /* Expand a Huffman table definition into the derived format */ 417dd7cddfSDavid du Colombier EXTERN(void) jpeg_make_c_derived_tbl 42*593dc095SDavid du Colombier JPP((j_compress_ptr cinfo, boolean isDC, int tblno, 43*593dc095SDavid du Colombier c_derived_tbl ** pdtbl)); 447dd7cddfSDavid du Colombier 457dd7cddfSDavid du Colombier /* Generate an optimal table definition given the specified counts */ 467dd7cddfSDavid du Colombier EXTERN(void) jpeg_gen_optimal_table 477dd7cddfSDavid du Colombier JPP((j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[])); 48