ref: b0a059537147237e868b4a8f07922ae8a349e55c
dir: /sys/src/cmd/gs/jpeg/jchuff.h/
/* * 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[]));