/*

 * 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[]));