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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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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
}
}