jchuff.h

Go to the documentation of this file.

/*
 * jchuff.h
 *
 * Copyright (C) 1991-1995, 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.
 */

/* 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,
                                JHUFF_TBL * htbl, 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[]));