nuclear@14: /*
nuclear@14:  * jchuff.h
nuclear@14:  *
nuclear@14:  * Copyright (C) 1991-1997, Thomas G. Lane.
nuclear@14:  * This file is part of the Independent JPEG Group's software.
nuclear@14:  * For conditions of distribution and use, see the accompanying README file.
nuclear@14:  *
nuclear@14:  * This file contains declarations for Huffman entropy encoding routines
nuclear@14:  * that are shared between the sequential encoder (jchuff.c) and the
nuclear@14:  * progressive encoder (jcphuff.c).  No other modules need to see these.
nuclear@14:  */
nuclear@14: 
nuclear@14: /* The legal range of a DCT coefficient is
nuclear@14:  *  -1024 .. +1023  for 8-bit data;
nuclear@14:  * -16384 .. +16383 for 12-bit data.
nuclear@14:  * Hence the magnitude should always fit in 10 or 14 bits respectively.
nuclear@14:  */
nuclear@14: 
nuclear@14: #if BITS_IN_JSAMPLE == 8
nuclear@14: #define MAX_COEF_BITS 10
nuclear@14: #else
nuclear@14: #define MAX_COEF_BITS 14
nuclear@14: #endif
nuclear@14: 
nuclear@14: /* Derived data constructed for each Huffman table */
nuclear@14: 
nuclear@14: typedef struct {
nuclear@14:   unsigned int ehufco[256];	/* code for each symbol */
nuclear@14:   char ehufsi[256];		/* length of code for each symbol */
nuclear@14:   /* If no code has been allocated for a symbol S, ehufsi[S] contains 0 */
nuclear@14: } c_derived_tbl;
nuclear@14: 
nuclear@14: /* Short forms of external names for systems with brain-damaged linkers. */
nuclear@14: 
nuclear@14: #ifdef NEED_SHORT_EXTERNAL_NAMES
nuclear@14: #define jpeg_make_c_derived_tbl	jMkCDerived
nuclear@14: #define jpeg_gen_optimal_table	jGenOptTbl
nuclear@14: #endif /* NEED_SHORT_EXTERNAL_NAMES */
nuclear@14: 
nuclear@14: /* Expand a Huffman table definition into the derived format */
nuclear@14: EXTERN(void) jpeg_make_c_derived_tbl
nuclear@14: 	JPP((j_compress_ptr cinfo, boolean isDC, int tblno,
nuclear@14: 	     c_derived_tbl ** pdtbl));
nuclear@14: 
nuclear@14: /* Generate an optimal table definition given the specified counts */
nuclear@14: EXTERN(void) jpeg_gen_optimal_table
nuclear@14: 	JPP((j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[]));