jchuff.h

Go to the documentation of this file.

/* +---------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)               |
   |                          http://www.mrpt.org/                             |
   |                                                                           |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file        |
   | See: http://www.mrpt.org/Authors - All rights reserved.                   |
   | Released under BSD License. See details in http://www.mrpt.org/License    |
   +---------------------------------------------------------------------------+ */
 
/* 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[]));