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MIPS: MIPS32r1: Added optimizations for FastLog2

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Functions VP8LFastLog2Slow and VP8LFastSLog2Slow

also: replaced some "% y" by "& (y-1)" in the C-version
(since y is a power-of-two)

Change-Id: I875170384e3c333812ca42d6ce7278aecabd60f0
This commit is contained in:
Jovan Zelincevic 2014-03-24 14:47:19 +01:00 committed by skal
parent 3fe0291530
commit baabf1ea3a
7 changed files with 133 additions and 6 deletions
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1
Android.mk
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@ -33,6 +33,7 @@ LOCAL_SRC_FILES := \
src/dsp/enc_mips32.c \
src/dsp/enc_sse2.c \
src/dsp/lossless.c \
src/dsp/lossless_mips32.c \
src/dsp/lossless_sse2.c \
src/dsp/upsampling.c \
src/dsp/upsampling_mips32.c \

1
Makefile.vc
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@ -174,6 +174,7 @@ DSP_DEC_OBJS = \
$(DIROBJ)\dsp\dec_neon.obj \
$(DIROBJ)\dsp\dec_sse2.obj \
$(DIROBJ)\dsp\lossless.obj \
$(DIROBJ)\dsp\lossless_mips32.obj \
$(DIROBJ)\dsp\lossless_neon.obj \
$(DIROBJ)\dsp\lossless_sse2.obj \
$(DIROBJ)\dsp\upsampling.obj \

1
makefile.unix
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@ -109,6 +109,7 @@ DSP_DEC_OBJS = \
src/dsp/dec_neon.o \
src/dsp/dec_sse2.o \
src/dsp/lossless.o \
src/dsp/lossless_mips32.o \
src/dsp/lossless_neon.o \
src/dsp/lossless_sse2.o \
src/dsp/upsampling.o \

1
src/dsp/Makefile.am
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@ -17,6 +17,7 @@ COMMON_SOURCES += dec_neon.c
COMMON_SOURCES += dec_sse2.c
COMMON_SOURCES += dsp.h
COMMON_SOURCES += lossless.c
COMMON_SOURCES += lossless_mips32.c
COMMON_SOURCES += lossless_neon.c
COMMON_SOURCES += lossless_sse2.c
COMMON_SOURCES += lossless.h

20
src/dsp/lossless.c
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@ -332,7 +332,7 @@ const uint8_t kPrefixEncodeExtraBitsValue[PREFIX_LOOKUP_IDX_MAX] = {
#define APPROX_LOG_WITH_CORRECTION_MAX 65536
#define APPROX_LOG_MAX 4096
#define LOG_2_RECIPROCAL 1.44269504088896338700465094007086
float VP8LFastSLog2Slow(int v) {
static float FastSLog2Slow(int v) {
assert(v >= LOG_LOOKUP_IDX_MAX);
if (v < APPROX_LOG_WITH_CORRECTION_MAX) {
int log_cnt = 0;
@ -351,14 +351,14 @@ float VP8LFastSLog2Slow(int v) {
// The correction factor: log(1 + d) ~ d; for very small d values, so
// log2(1 + (v % y) / v) ~ LOG_2_RECIPROCAL * (v % y)/v
// LOG_2_RECIPROCAL ~ 23/16
correction = (23 * (orig_v % y)) >> 4;
correction = (23 * (orig_v & (y - 1))) >> 4;
return v_f * (kLog2Table[v] + log_cnt) + correction;
} else {
return (float)(LOG_2_RECIPROCAL * v * log((double)v));
}
}
float VP8LFastLog2Slow(int v) {
static float FastLog2Slow(int v) {
assert(v >= LOG_LOOKUP_IDX_MAX);
if (v < APPROX_LOG_WITH_CORRECTION_MAX) {
int log_cnt = 0;
@ -374,7 +374,7 @@ float VP8LFastLog2Slow(int v) {
if (orig_v >= APPROX_LOG_MAX) {
// Since the division is still expensive, add this correction factor only
// for large values of 'v'.
const int correction = (23 * (orig_v % y)) >> 4;
const int correction = (23 * (orig_v & (y - 1))) >> 4;
log_2 += (double)correction / orig_v;
}
return (float)log_2;
@ -1473,8 +1473,12 @@ VP8LConvertFunc VP8LConvertBGRAToRGBA4444;
VP8LConvertFunc VP8LConvertBGRAToRGB565;
VP8LConvertFunc VP8LConvertBGRAToBGR;
VP8LFastLog2SlowFunc VP8LFastLog2Slow;
VP8LFastLog2SlowFunc VP8LFastSLog2Slow;
extern void VP8LDspInitSSE2(void);
extern void VP8LDspInitNEON(void);
extern void VP8LDspInitMIPS32(void);
void VP8LDspInit(void) {
memcpy(VP8LPredictors, kPredictorsC, sizeof(VP8LPredictors));
@ -1491,6 +1495,9 @@ void VP8LDspInit(void) {
VP8LConvertBGRAToRGB565 = VP8LConvertBGRAToRGB565_C;
VP8LConvertBGRAToBGR = VP8LConvertBGRAToBGR_C;
VP8LFastLog2Slow = FastLog2Slow;
VP8LFastSLog2Slow = FastSLog2Slow;
// If defined, use CPUInfo() to overwrite some pointers with faster versions.
if (VP8GetCPUInfo != NULL) {
#if defined(WEBP_USE_SSE2)
@ -1502,6 +1509,11 @@ void VP8LDspInit(void) {
if (VP8GetCPUInfo(kNEON)) {
VP8LDspInitNEON();
}
#endif
#if defined(WEBP_USE_MIPS32)
if (VP8GetCPUInfo(kMIPS32)) {
VP8LDspInitMIPS32();
}
#endif
}
}

7
src/dsp/lossless.h
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@ -122,8 +122,11 @@ static WEBP_INLINE uint32_t VP8LSubSampleSize(uint32_t size,
#define LOG_LOOKUP_IDX_MAX 256
extern const float kLog2Table[LOG_LOOKUP_IDX_MAX];
extern const float kSLog2Table[LOG_LOOKUP_IDX_MAX];
float VP8LFastLog2Slow(int v);
float VP8LFastSLog2Slow(int v);
typedef float (*VP8LFastLog2SlowFunc)(int v);
extern VP8LFastLog2SlowFunc VP8LFastLog2Slow;
extern VP8LFastLog2SlowFunc VP8LFastSLog2Slow;
static WEBP_INLINE float VP8LFastLog2(int v) {
return (v < LOG_LOOKUP_IDX_MAX) ? kLog2Table[v] : VP8LFastLog2Slow(v);
}

108
src/dsp/lossless_mips32.c Normal file
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@ -0,0 +1,108 @@
// Copyright 2014 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING 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.
// -----------------------------------------------------------------------------
//
// MIPS version of lossless functions
//
// Author(s): Jovan Zelincevic (jovan.zelincevic@imgtec.com)
#include "./dsp.h"
#include "./lossless.h"
#if defined(WEBP_USE_MIPS32)
#include <math.h>
#include <stdlib.h>
#include <assert.h>
#define APPROX_LOG_WITH_CORRECTION_MAX 65536
#define APPROX_LOG_MAX 4096
#define LOG_2_RECIPROCAL 1.44269504088896338700465094007086
static float FastSLog2SlowMIPS32(int v) {
assert(v >= LOG_LOOKUP_IDX_MAX);
if (v < APPROX_LOG_WITH_CORRECTION_MAX) {
int log_cnt, y, correction;
const int c24 = 24;
const float v_f = (float)v;
int temp;
// Xf = 256 = 2^8
// log_cnt is index of leading one in upper 24 bits
__asm__ volatile(
"clz %[log_cnt], %[v] \n\t"
"addiu %[y], $zero, 1 \n\t"
"subu %[log_cnt], %[c24], %[log_cnt] \n\t"
"sllv %[y], %[y], %[log_cnt] \n\t"
"srlv %[temp], %[v], %[log_cnt] \n\t"
: [log_cnt]"=&r"(log_cnt), [y]"=&r"(y),
[temp]"=r"(temp)
: [c24]"r"(c24), [v]"r"(v)
);
// vf = (2^log_cnt) * Xf; where y = 2^log_cnt and Xf < 256
// Xf = floor(Xf) * (1 + (v % y) / v)
// log2(Xf) = log2(floor(Xf)) + log2(1 + (v % y) / v)
// The correction factor: log(1 + d) ~ d; for very small d values, so
// log2(1 + (v % y) / v) ~ LOG_2_RECIPROCAL * (v % y)/v
// LOG_2_RECIPROCAL ~ 23/16
// (v % y) = (v % 2^log_cnt) = v & (2^log_cnt - 1)
correction = (23 * (v & (y - 1))) >> 4;
return v_f * (kLog2Table[temp] + log_cnt) + correction;
} else {
return (float)(LOG_2_RECIPROCAL * v * log((double)v));
}
}
static float FastLog2SlowMIPS32(int v) {
assert(v >= LOG_LOOKUP_IDX_MAX);
if (v < APPROX_LOG_WITH_CORRECTION_MAX) {
int log_cnt, y;
const int c24 = 24;
double log_2;
int temp;
__asm__ volatile(
"clz %[log_cnt], %[v] \n\t"
"addiu %[y], $zero, 1 \n\t"
"subu %[log_cnt], %[c24], %[log_cnt] \n\t"
"sllv %[y], %[y], %[log_cnt] \n\t"
"srlv %[temp], %[v], %[log_cnt] \n\t"
: [log_cnt]"=&r"(log_cnt), [y]"=&r"(y),
[temp]"=r"(temp)
: [c24]"r"(c24), [v]"r"(v)
);
log_2 = kLog2Table[temp] + log_cnt;
if (v >= APPROX_LOG_MAX) {
// Since the division is still expensive, add this correction factor only
// for large values of 'v'.
const int correction = (23 * (v & (y - 1))) >> 4;
log_2 += (double)correction / v;
}
return (float)log_2;
} else {
return (float)(LOG_2_RECIPROCAL * log((double)v));
}
}
#endif // WEBP_USE_MIPS32
//------------------------------------------------------------------------------
// Entry point
extern void VP8LDspInitMIPS32(void);
void VP8LDspInitMIPS32(void) {
#if defined(WEBP_USE_MIPS32)
VP8LFastSLog2Slow = FastSLog2SlowMIPS32;
VP8LFastLog2Slow = FastLog2SlowMIPS32;
#endif // WEBP_USE_MIPS32
}