ref: 00d566eae1591078ecbadcaf67e30b2778c06b4e
dir: /vp8/decoder/dboolhuff.h/
/*
* Copyright (c) 2010 The VP8 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 "vpx_ports/config.h"
#include "vpx_ports/mem.h"
#include "vpx/vpx_integer.h"
/* Size of the bool decoder backing storage
*
* This size was chosen to be greater than the worst case encoding of a
* single macroblock. This was calcluated as follows (python):
*
* def max_cost(prob):
* return max(prob_costs[prob], prob_costs[255-prob]) / 256;
*
* tree_nodes_cost = 7 * max_cost(255)
* extra_bits_cost = sum([max_cost(bit) for bit in extra_bits])
* sign_bit_cost = max_cost(128)
* total_cost = tree_nodes_cost + extra_bits_cost + sign_bit_cost
*
* where the prob_costs table was taken from the C vp8_prob_cost table in
* boolhuff.c and the extra_bits table was taken from the 11 extrabits for
* a category 6 token as defined in vp8d_token_extra_bits2/detokenize.c
*
* This equation produced a maximum of 79 bits per coefficient. Scaling up
* to the macroblock level:
*
* 79 bits/coeff * 16 coeff/block * 25 blocks/macroblock = 31600 b/mb
*
* 4096 bytes = 32768 bits > 31600
*/
#define VP8_BOOL_DECODER_SZ 4096
#define VP8_BOOL_DECODER_MASK (VP8_BOOL_DECODER_SZ-1)
#define VP8_BOOL_DECODER_PTR_MASK (~(uintptr_t)(VP8_BOOL_DECODER_SZ))
struct vp8_dboolhuff_rtcd_vtable;
typedef struct
{
unsigned int lowvalue;
unsigned int range;
unsigned int value;
int count;
const unsigned char *user_buffer;
unsigned int user_buffer_sz;
unsigned char *decode_buffer;
const unsigned char *read_ptr;
unsigned char *write_ptr;
#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_stop(sym) void sym(BOOL_DECODER *bc)
#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_stop
#define vp8_dbool_stop vp8dx_stop_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_stop(vp8_dbool_stop);
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_stop((*vp8_dbool_stop_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_stop_fn_t stop;
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
static unsigned char *br_ptr_advance(const unsigned char *_ptr,
unsigned int n)
{
uintptr_t ptr = (uintptr_t)_ptr;
ptr += n;
ptr &= VP8_BOOL_DECODER_PTR_MASK;
return (void *)ptr;
}
DECLARE_ALIGNED(16, extern const unsigned int, 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_stop_decode(BOOL_DECODER *br) {
DBOOLHUFF_INVOKE(br->rtcd, stop)(br);
}
static void vp8dx_bool_decoder_fill(BOOL_DECODER *br) {
DBOOLHUFF_INVOKE(br->rtcd, fill)(br);
}
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;
unsigned int split;
unsigned int bigsplit;
register unsigned int range = br->range;
register unsigned int value = br->value;
split = 1 + (((range - 1) * probability) >> 8);
bigsplit = (split << 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
}*/
{
int count = br->count;
register unsigned int shift = vp8dx_bitreader_norm[range];
range <<= shift;
value <<= shift;
count -= shift;
if (count <= 0)
{
value |= (*br->read_ptr) << (-count);
br->read_ptr = br_ptr_advance(br->read_ptr, 1);
count += 8 ;
}
br->count = count;
}
br->value = value;
br->range = range;
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