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/*
* Copyright (c) 1992 The Regents of the University of California.
* All rights reserved.
*
* Permission to use, copy, modify, and distribute this software and its
* documentation for any purpose, without fee, and without written agreement is
* hereby granted, provided that the above copyright notice and the following
* two paragraphs appear in all copies of this software.
*
* IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
* OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
* CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*/
/*
* decoders.h
*
* This file contains the declarations of structures required for Huffman
* decoding
*
*/
/* Include util.h for bit i/o parsing macros. */
#include "util.h"
/* Code for unbound values in decoding tables */
#define ERROR -1
#define DCT_ERROR 63
#define MACRO_BLOCK_STUFFING 34
#define MACRO_BLOCK_ESCAPE 35
/* Two types of DCT Coefficients */
#define DCT_COEFF_FIRST 0
#define DCT_COEFF_NEXT 1
/* Special values for DCT Coefficients */
#define END_OF_BLOCK 62
#define ESCAPE 61
/* Structure for an entry in the decoding table of
* macroblock_address_increment */
typedef struct {
unsigned int value; /* value for macroblock_address_increment */
int num_bits; /* length of the Huffman code */
} mb_addr_inc_entry;
/* Decoding table for macroblock_address_increment */
mb_addr_inc_entry mb_addr_inc[2048];
/* Structure for an entry in the decoding table of macroblock_type */
typedef struct {
unsigned int mb_quant; /* macroblock_quant */
unsigned int mb_motion_forward; /* macroblock_motion_forward */
unsigned int mb_motion_backward; /* macroblock_motion_backward */
unsigned int mb_pattern; /* macroblock_pattern */
unsigned int mb_intra; /* macroblock_intra */
int num_bits; /* length of the Huffman code */
} mb_type_entry;
/* Decoding table for macroblock_type in predictive-coded pictures */
mb_type_entry mb_type_P[64];
/* Decoding table for macroblock_type in bidirectionally-coded pictures */
mb_type_entry mb_type_B[64];
/* Structures for an entry in the decoding table of coded_block_pattern */
typedef struct {
unsigned int cbp; /* coded_block_pattern */
int num_bits; /* length of the Huffman code */
} coded_block_pattern_entry;
/* External declaration of coded block pattern table. */
extern coded_block_pattern_entry coded_block_pattern[512];
/* Structure for an entry in the decoding table of motion vectors */
typedef struct {
int code; /* value for motion_horizontal_forward_code,
* motion_vertical_forward_code,
* motion_horizontal_backward_code, or
* motion_vertical_backward_code.
*/
int num_bits; /* length of the Huffman code */
} motion_vectors_entry;
/* Decoding table for motion vectors */
motion_vectors_entry motion_vectors[2048];
/* Structure for an entry in the decoding table of dct_dc_size */
typedef struct {
unsigned int value; /* value of dct_dc_size (luminance or chrominance) */
int num_bits; /* length of the Huffman code */
} dct_dc_size_entry;
/* External declaration of dct dc size lumiance table. */
extern dct_dc_size_entry dct_dc_size_luminance[128];
/* External declaration of dct dc size chrom table. */
extern dct_dc_size_entry dct_dc_size_chrominance[256];
/* DCT coeff tables. */
#define RUN_MASK 0xfc00
#define LEVEL_MASK 0x03f0
#define NUM_MASK 0x000f
#define RUN_SHIFT 10
#define LEVEL_SHIFT 4
/* External declaration of dct coeff tables. */
extern unsigned short int dct_coeff_tbl_0[256];
extern unsigned short int dct_coeff_tbl_1[16];
extern unsigned short int dct_coeff_tbl_2[4];
extern unsigned short int dct_coeff_tbl_3[4];
extern unsigned short int dct_coeff_next[256];
extern unsigned short int dct_coeff_first[256];
#define DecodeDCTDCSizeLum(macro_val) \
{ \
unsigned int index; \
\
show_bits7(&index); \
\
*(macro_val) = dct_dc_size_luminance[index].value; \
\
flush_bits(dct_dc_size_luminance[index].num_bits); \
}
#define DecodeDCTDCSizeChrom(macro_val) \
{ \
unsigned int index; \
\
show_bits8(&index); \
\
*(macro_val) = dct_dc_size_chrominance[index].value; \
\
flush_bits(dct_dc_size_chrominance[index].num_bits); \
}
#define DecodeDCTCoeff(type, run, level) \
{ \
unsigned int temp_run, index, temp_level, num_bits; \
unsigned short int *dct_coeff_tbl; \
unsigned int value; \
\
show_bits8(&index); \
if (type == DCT_COEFF_FIRST) \
dct_coeff_tbl = dct_coeff_first; \
else \
dct_coeff_tbl = dct_coeff_next; \
\
if (index > 3) { \
value = dct_coeff_tbl[index]; \
temp_run = (value & RUN_MASK) >> RUN_SHIFT; \
if (temp_run == END_OF_BLOCK) { \
*run = END_OF_BLOCK; \
*level = END_OF_BLOCK; \
} \
else { \
num_bits = (value & NUM_MASK) + 1; \
flush_bits(num_bits); \
if (temp_run != ESCAPE) { \
value = dct_coeff_tbl[index]; \
temp_level = (value & LEVEL_MASK) >> LEVEL_SHIFT; \
*run = temp_run; \
get_bits1(&value); \
*level = value ? -temp_level : temp_level; \
} \
else { /* temp_run == ESCAPE */ \
get_bits6(run); \
get_bits8(&temp_level); \
if (temp_level != 0 && temp_level != 128) \
*level = ((int) (temp_level << 24)) >> 24; \
else if (temp_level == 0) { \
get_bits8(&temp_level); \
*level = temp_level; \
assert(*level >= 128); \
} \
else { \
get_bits8(&temp_level); \
*level = temp_level - 256; \
assert(*level <= -128 && *level >= -255); \
} \
} \
} \
} \
else { \
if (index == 2) { \
show_bits10(&index); \
value = dct_coeff_tbl_2[index & 3]; \
} \
else if (index == 3) { \
show_bits10(&index); \
value = dct_coeff_tbl_3[index & 3]; \
} \
else if (index == 1) { \
show_bits12(&index); \
value = dct_coeff_tbl_1[index & 15]; \
} \
else { /* index == 0 */ \
show_bits16(&index); \
value = dct_coeff_tbl_0[index & 255]; \
} \
*run = (value & RUN_MASK) >> RUN_SHIFT; \
temp_level = (value & LEVEL_MASK) >> LEVEL_SHIFT; \
num_bits = (value & NUM_MASK) + 1; \
flush_bits(num_bits); \
get_bits1(&value); \
*level = value ? -temp_level : temp_level; \
} \
}
#define DecodeDCTCoeffFirst(runval, levelval) \
{ \
DecodeDCTCoeff(DCT_COEFF_FIRST, runval, levelval); \
}
#define DecodeDCTCoeffNext(runval, levelval) \
{ \
DecodeDCTCoeff(DCT_COEFF_NEXT, runval, levelval); \
}
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