7e3acc0e0a
The IJG README file has been renamed to README.ijg, in order to avoid confusion (many people were assuming that that was our project's README file and weren't reading README-turbo.txt) and to lay the groundwork for markdown versions of the libjpeg-turbo README and build instructions.
44 lines
1.4 KiB
C
44 lines
1.4 KiB
C
/*
|
|
* jchuff.h
|
|
*
|
|
* This file was part of the Independent JPEG Group's software:
|
|
* Copyright (C) 1991-1997, Thomas G. Lane.
|
|
* It was modified by The libjpeg-turbo Project to include only code relevant
|
|
* to libjpeg-turbo.
|
|
* For conditions of distribution and use, see the accompanying README.ijg
|
|
* 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;
|
|
|
|
/* Expand a Huffman table definition into the derived format */
|
|
EXTERN(void) jpeg_make_c_derived_tbl
|
|
(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
|
|
(j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[]);
|