gecko/media/libvpx/vp8/decoder/dboolhuff.h
2010-11-08 09:47:17 +02:00

210 lines
5.8 KiB
C

/*
* Copyright (c) 2010 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef DBOOLHUFF_H
#define DBOOLHUFF_H
#include <stddef.h>
#include <limits.h>
#include "vpx_ports/config.h"
#include "vpx_ports/mem.h"
#include "vpx/vpx_integer.h"
typedef size_t VP8_BD_VALUE;
# define VP8_BD_VALUE_SIZE ((int)sizeof(VP8_BD_VALUE)*CHAR_BIT)
/*This is meant to be a large, positive constant that can still be efficiently
loaded as an immediate (on platforms like ARM, for example).
Even relatively modest values like 100 would work fine.*/
# define VP8_LOTS_OF_BITS (0x40000000)
struct vp8_dboolhuff_rtcd_vtable;
typedef struct
{
const unsigned char *user_buffer_end;
const unsigned char *user_buffer;
VP8_BD_VALUE value;
int count;
unsigned int range;
#if CONFIG_RUNTIME_CPU_DETECT
struct vp8_dboolhuff_rtcd_vtable *rtcd;
#endif
} BOOL_DECODER;
#define prototype_dbool_start(sym) int sym(BOOL_DECODER *br, \
const unsigned char *source, unsigned int source_sz)
#define prototype_dbool_fill(sym) void sym(BOOL_DECODER *br)
#define prototype_dbool_debool(sym) int sym(BOOL_DECODER *br, int probability)
#define prototype_dbool_devalue(sym) int sym(BOOL_DECODER *br, int bits)
#if ARCH_ARM
#include "arm/dboolhuff_arm.h"
#endif
#ifndef vp8_dbool_start
#define vp8_dbool_start vp8dx_start_decode_c
#endif
#ifndef vp8_dbool_fill
#define vp8_dbool_fill vp8dx_bool_decoder_fill_c
#endif
#ifndef vp8_dbool_debool
#define vp8_dbool_debool vp8dx_decode_bool_c
#endif
#ifndef vp8_dbool_devalue
#define vp8_dbool_devalue vp8dx_decode_value_c
#endif
extern prototype_dbool_start(vp8_dbool_start);
extern prototype_dbool_fill(vp8_dbool_fill);
extern prototype_dbool_debool(vp8_dbool_debool);
extern prototype_dbool_devalue(vp8_dbool_devalue);
typedef prototype_dbool_start((*vp8_dbool_start_fn_t));
typedef prototype_dbool_fill((*vp8_dbool_fill_fn_t));
typedef prototype_dbool_debool((*vp8_dbool_debool_fn_t));
typedef prototype_dbool_devalue((*vp8_dbool_devalue_fn_t));
typedef struct vp8_dboolhuff_rtcd_vtable {
vp8_dbool_start_fn_t start;
vp8_dbool_fill_fn_t fill;
vp8_dbool_debool_fn_t debool;
vp8_dbool_devalue_fn_t devalue;
} vp8_dboolhuff_rtcd_vtable_t;
/* There are no processor-specific versions of these
* functions right now. Disable RTCD to avoid using
* function pointers which gives a speed boost
*/
/*#ifdef ENABLE_RUNTIME_CPU_DETECT
#define DBOOLHUFF_INVOKE(ctx,fn) (ctx)->fn
#define IF_RTCD(x) (x)
#else*/
#define DBOOLHUFF_INVOKE(ctx,fn) vp8_dbool_##fn
#define IF_RTCD(x) NULL
/*#endif*/
DECLARE_ALIGNED(16, extern const unsigned char, vp8dx_bitreader_norm[256]);
/* wrapper functions to hide RTCD. static means inline means hopefully no
* penalty
*/
static int vp8dx_start_decode(BOOL_DECODER *br,
struct vp8_dboolhuff_rtcd_vtable *rtcd,
const unsigned char *source, unsigned int source_sz) {
#if CONFIG_RUNTIME_CPU_DETECT
br->rtcd = rtcd;
#endif
return DBOOLHUFF_INVOKE(rtcd, start)(br, source, source_sz);
}
static void vp8dx_bool_decoder_fill(BOOL_DECODER *br) {
DBOOLHUFF_INVOKE(br->rtcd, fill)(br);
}
/*The refill loop is used in several places, so define it in a macro to make
sure they're all consistent.
An inline function would be cleaner, but has a significant penalty, because
multiple BOOL_DECODER fields must be modified, and the compiler is not smart
enough to eliminate the stores to those fields and the subsequent reloads
from them when inlining the function.*/
#define VP8DX_BOOL_DECODER_FILL(_count,_value,_bufptr,_bufend) \
do \
{ \
int shift; \
for(shift = VP8_BD_VALUE_SIZE - 8 - ((_count) + 8); shift >= 0; ) \
{ \
if((_bufptr) >= (_bufend)) { \
(_count) = VP8_LOTS_OF_BITS; \
break; \
} \
(_count) += 8; \
(_value) |= (VP8_BD_VALUE)*(_bufptr)++ << shift; \
shift -= 8; \
} \
} \
while(0)
static int vp8dx_decode_bool(BOOL_DECODER *br, int probability) {
/*
* Until optimized versions of this function are available, we
* keep the implementation in the header to allow inlining.
*
*return DBOOLHUFF_INVOKE(br->rtcd, debool)(br, probability);
*/
unsigned int bit = 0;
VP8_BD_VALUE value;
unsigned int split;
VP8_BD_VALUE bigsplit;
int count;
unsigned int range;
value = br->value;
count = br->count;
range = br->range;
split = 1 + (((range - 1) * probability) >> 8);
bigsplit = (VP8_BD_VALUE)split << (VP8_BD_VALUE_SIZE - 8);
range = split;
if (value >= bigsplit)
{
range = br->range - split;
value = value - bigsplit;
bit = 1;
}
/*if(range>=0x80)
{
br->value = value;
br->range = range;
return bit
}*/
{
register unsigned int shift = vp8dx_bitreader_norm[range];
range <<= shift;
value <<= shift;
count -= shift;
}
br->value = value;
br->count = count;
br->range = range;
if(count < 0)
vp8dx_bool_decoder_fill(br);
return bit;
}
static int vp8_decode_value(BOOL_DECODER *br, int bits)
{
/*
* Until optimized versions of this function are available, we
* keep the implementation in the header to allow inlining.
*
*return DBOOLHUFF_INVOKE(br->rtcd, devalue)(br, bits);
*/
int z = 0;
int bit;
for (bit = bits - 1; bit >= 0; bit--)
{
z |= (vp8dx_decode_bool(br, 0x80) << bit);
}
return z;
}
#endif