227 lines
6.4 KiB
C
227 lines
6.4 KiB
C
/*
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* Copyright (c) 2010 The VP8 project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license and patent
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* grant that can be found in the LICENSE file in the root of the source
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* tree. All contributing project authors may be found in the AUTHORS
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* file in the root of the source tree.
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*/
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#ifndef DBOOLHUFF_H
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#define DBOOLHUFF_H
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#include "vpx_ports/config.h"
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#include "vpx_ports/mem.h"
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#include "vpx_ports/vpx_integer.h"
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/* Size of the bool decoder backing storage
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*
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* This size was chosen to be greater than the worst case encoding of a
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* single macroblock. This was calcluated as follows (python):
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*
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* def max_cost(prob):
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* return max(prob_costs[prob], prob_costs[255-prob]) / 256;
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*
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* tree_nodes_cost = 7 * max_cost(255)
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* extra_bits_cost = sum([max_cost(bit) for bit in extra_bits])
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* sign_bit_cost = max_cost(128)
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* total_cost = tree_nodes_cost + extra_bits_cost + sign_bit_cost
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*
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* where the prob_costs table was taken from the C vp8_prob_cost table in
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* boolhuff.c and the extra_bits table was taken from the 11 extrabits for
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* a category 6 token as defined in vp8d_token_extra_bits2/detokenize.c
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*
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* This equation produced a maximum of 79 bits per coefficient. Scaling up
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* to the macroblock level:
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*
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* 79 bits/coeff * 16 coeff/block * 25 blocks/macroblock = 31600 b/mb
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*
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* 4096 bytes = 32768 bits > 31600
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*/
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#define VP8_BOOL_DECODER_SZ 4096
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#define VP8_BOOL_DECODER_MASK (VP8_BOOL_DECODER_SZ-1)
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#define VP8_BOOL_DECODER_PTR_MASK (~(uintptr_t)(VP8_BOOL_DECODER_SZ))
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struct vp8_dboolhuff_rtcd_vtable;
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typedef struct
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{
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unsigned int lowvalue;
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unsigned int range;
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unsigned int value;
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int count;
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const unsigned char *user_buffer;
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unsigned int user_buffer_sz;
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unsigned char *decode_buffer;
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const unsigned char *read_ptr;
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unsigned char *write_ptr;
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#if CONFIG_RUNTIME_CPU_DETECT
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struct vp8_dboolhuff_rtcd_vtable *rtcd;
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#endif
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} BOOL_DECODER;
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#define prototype_dbool_start(sym) int sym(BOOL_DECODER *br, \
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const unsigned char *source, unsigned int source_sz)
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#define prototype_dbool_stop(sym) void sym(BOOL_DECODER *bc)
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#define prototype_dbool_fill(sym) void sym(BOOL_DECODER *br)
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#define prototype_dbool_debool(sym) int sym(BOOL_DECODER *br, int probability)
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#define prototype_dbool_devalue(sym) int sym(BOOL_DECODER *br, int bits);
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#if ARCH_ARM
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#include "arm/dboolhuff_arm.h"
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#endif
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#ifndef vp8_dbool_start
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#define vp8_dbool_start vp8dx_start_decode_c
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#endif
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#ifndef vp8_dbool_stop
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#define vp8_dbool_stop vp8dx_stop_decode_c
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#endif
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#ifndef vp8_dbool_fill
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#define vp8_dbool_fill vp8dx_bool_decoder_fill_c
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#endif
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#ifndef vp8_dbool_debool
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#define vp8_dbool_debool vp8dx_decode_bool_c
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#endif
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#ifndef vp8_dbool_devalue
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#define vp8_dbool_devalue vp8dx_decode_value_c
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#endif
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extern prototype_dbool_start(vp8_dbool_start);
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extern prototype_dbool_stop(vp8_dbool_stop);
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extern prototype_dbool_fill(vp8_dbool_fill);
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extern prototype_dbool_debool(vp8_dbool_debool);
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extern prototype_dbool_devalue(vp8_dbool_devalue);
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typedef prototype_dbool_start((*vp8_dbool_start_fn_t));
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typedef prototype_dbool_stop((*vp8_dbool_stop_fn_t));
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typedef prototype_dbool_fill((*vp8_dbool_fill_fn_t));
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typedef prototype_dbool_debool((*vp8_dbool_debool_fn_t));
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typedef prototype_dbool_devalue((*vp8_dbool_devalue_fn_t));
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typedef struct vp8_dboolhuff_rtcd_vtable {
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vp8_dbool_start_fn_t start;
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vp8_dbool_stop_fn_t stop;
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vp8_dbool_fill_fn_t fill;
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vp8_dbool_debool_fn_t debool;
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vp8_dbool_devalue_fn_t devalue;
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} vp8_dboolhuff_rtcd_vtable_t;
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// There are no processor-specific versions of these
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// functions right now. Disable RTCD to avoid using
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// function pointers which gives a speed boost
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//#ifdef ENABLE_RUNTIME_CPU_DETECT
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//#define DBOOLHUFF_INVOKE(ctx,fn) (ctx)->fn
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//#define IF_RTCD(x) (x)
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//#else
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#define DBOOLHUFF_INVOKE(ctx,fn) vp8_dbool_##fn
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#define IF_RTCD(x) NULL
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//#endif
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static unsigned char *br_ptr_advance(const unsigned char *_ptr,
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unsigned int n)
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{
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uintptr_t ptr = (uintptr_t)_ptr;
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ptr += n;
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ptr &= VP8_BOOL_DECODER_PTR_MASK;
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return (void *)ptr;
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}
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DECLARE_ALIGNED(16, extern const unsigned int, vp8dx_bitreader_norm[256]);
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/* wrapper functions to hide RTCD. static means inline means hopefully no
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* penalty
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*/
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static int vp8dx_start_decode(BOOL_DECODER *br,
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struct vp8_dboolhuff_rtcd_vtable *rtcd,
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const unsigned char *source, unsigned int source_sz) {
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#if CONFIG_RUNTIME_CPU_DETECT
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br->rtcd = rtcd;
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#endif
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return DBOOLHUFF_INVOKE(rtcd, start)(br, source, source_sz);
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}
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static void vp8dx_stop_decode(BOOL_DECODER *br) {
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DBOOLHUFF_INVOKE(br->rtcd, stop)(br);
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}
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static void vp8dx_bool_decoder_fill(BOOL_DECODER *br) {
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DBOOLHUFF_INVOKE(br->rtcd, fill)(br);
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}
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static int vp8dx_decode_bool(BOOL_DECODER *br, int probability) {
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/*
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* Until optimized versions of this function are available, we
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* keep the implementation in the header to allow inlining.
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*
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*return DBOOLHUFF_INVOKE(br->rtcd, debool)(br, probability);
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*/
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unsigned int bit = 0;
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unsigned int split;
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unsigned int bigsplit;
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register unsigned int range = br->range;
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register unsigned int value = br->value;
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split = 1 + (((range - 1) * probability) >> 8);
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bigsplit = (split << 8);
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range = split;
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if (value >= bigsplit)
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{
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range = br->range - split;
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value = value - bigsplit;
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bit = 1;
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}
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/*if(range>=0x80)
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{
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br->value = value;
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br->range = range;
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return bit
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}*/
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{
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int count = br->count;
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register unsigned int shift = vp8dx_bitreader_norm[range];
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range <<= shift;
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value <<= shift;
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count -= shift;
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if (count <= 0)
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{
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value |= (*br->read_ptr) << (-count);
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br->read_ptr = br_ptr_advance(br->read_ptr, 1);
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count += 8 ;
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}
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br->count = count;
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}
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br->value = value;
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br->range = range;
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return bit;
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}
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static int vp8_decode_value(BOOL_DECODER *br, int bits)
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{
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/*
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* Until optimized versions of this function are available, we
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* keep the implementation in the header to allow inlining.
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*
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*return DBOOLHUFF_INVOKE(br->rtcd, devalue)(br, bits);
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*/
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int z = 0;
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int bit;
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for (bit = bits - 1; bit >= 0; bit--)
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{
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z |= (vp8dx_decode_bool(br, 0x80) << bit);
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}
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return z;
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}
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#endif
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