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ARM optimised vp56_rac_get_prob() 

Approximately 3% faster on Cortex-A8.

Signed-off-by: Mans Rullgard <mans@mansr.com>
This commit is contained in:
Mans Rullgard 2010-12-22 12:57:53 +00:00
parent aa8ac53b51
commit 7da48fd011
2 changed files with 97 additions and 1 deletions
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92
libavcodec/arm/vp56_arith.h Normal file
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@ -0,0 +1,92 @@
/*
* Copyright (C) 2010 Mans Rullgard <mans@mansr.com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVCODEC_ARM_VP56_ARITH_H
#define AVCODEC_ARM_VP56_ARITH_H
#if HAVE_ARMV6 && HAVE_INLINE_ASM
#define vp56_rac_get_prob vp56_rac_get_prob_armv6
static inline int vp56_rac_get_prob_armv6(VP56RangeCoder *c, int pr)
{
unsigned shift = ff_vp56_norm_shift[c->high];
unsigned code_word = c->code_word << shift;
unsigned high = c->high << shift;
unsigned bit;
__asm__ volatile ("adds %3, %3, %0 \n"
"cmpcs %7, %4 \n"
"ldrcsh %2, [%4], #2 \n"
"rsb %0, %6, #256 \n"
"smlabb %0, %5, %6, %0 \n"
"rev16cs %2, %2 \n"
"orrcs %1, %1, %2, lsl %3 \n"
"subcs %3, %3, #16 \n"
"lsr %0, %0, #8 \n"
"cmp %1, %0, lsl #16 \n"
"subge %1, %1, %0, lsl #16 \n"
"subge %0, %5, %0 \n"
"movge %2, #1 \n"
"movlt %2, #0 \n"
: "=&r"(c->high), "=&r"(c->code_word), "=&r"(bit),
"+&r"(c->bits), "+&r"(c->buffer)
: "r"(high), "r"(pr), "r"(c->end - 1),
"0"(shift), "1"(code_word));
return bit;
}
#define vp56_rac_get_prob_branchy vp56_rac_get_prob_branchy_armv6
static inline int vp56_rac_get_prob_branchy_armv6(VP56RangeCoder *c, int pr)
{
unsigned shift = ff_vp56_norm_shift[c->high];
unsigned code_word = c->code_word << shift;
unsigned high = c->high << shift;
unsigned low;
unsigned tmp;
__asm__ volatile ("adds %3, %3, %0 \n"
"cmpcs %7, %4 \n"
"ldrcsh %2, [%4], #2 \n"
"rsb %0, %6, #256 \n"
"smlabb %0, %5, %6, %0 \n"
"rev16cs %2, %2 \n"
"orrcs %1, %1, %2, lsl %3 \n"
"subcs %3, %3, #16 \n"
"lsr %0, %0, #8 \n"
"lsl %2, %0, #16 \n"
: "=&r"(low), "+&r"(code_word), "=&r"(tmp),
"+&r"(c->bits), "+&r"(c->buffer)
: "r"(high), "r"(pr), "r"(c->end - 1), "0"(shift));
if (code_word >= tmp) {
c->high = high - low;
c->code_word = code_word - tmp;
return 1;
}
c->high = low;
c->code_word = code_word;
return 0;
}
#endif
#endif

6
libavcodec/vp56.h
View File

@ -201,7 +201,9 @@ static av_always_inline unsigned int vp56_rac_renorm(VP56RangeCoder *c)
return code_word;
}
#if ARCH_X86
#if ARCH_ARM
#include "arm/vp56_arith.h"
#elif ARCH_X86
#include "x86/vp56_arith.h"
#endif
@ -221,6 +223,7 @@ static av_always_inline int vp56_rac_get_prob(VP56RangeCoder *c, uint8_t prob)
}
#endif
#ifndef vp56_rac_get_prob_branchy
// branchy variant, to be used where there's a branch based on the bit decoded
static av_always_inline int vp56_rac_get_prob_branchy(VP56RangeCoder *c, int prob)
{
@ -238,6 +241,7 @@ static av_always_inline int vp56_rac_get_prob_branchy(VP56RangeCoder *c, int pro
c->code_word = code_word;
return 0;
}
#endif
static av_always_inline int vp56_rac_get(VP56RangeCoder *c)
{