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histogram: add log2 wrapper

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Change-Id: I5e68efaf5f763a42ace1af83f4b7887e0ddfd099
This commit is contained in:
James Zern 2012-06-04 18:36:38 -07:00
parent 8c34378ff3
commit 9b71502669
1 changed files with 14 additions and 0 deletions
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14
src/enc/histogram.c
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@ -7,6 +7,9 @@
//
// Author: Jyrki Alakuijala (jyrki@google.com)
//
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef USE_LOSSLESS_ENCODER
@ -17,6 +20,17 @@
#include "./histogram.h"
#include "../dsp/lossless.h"
#if defined(_MSC_VER) && !defined(NOT_HAVE_LOG2)
# define NOT_HAVE_LOG2 1
#endif
#ifdef NOT_HAVE_LOG2
static WEBP_INLINE double log2(double d) {
const double kLog2Reciprocal = 1.442695040888963;
return log(d) * kLog2Reciprocal;
}
#endif
static void HistogramClear(VP8LHistogram* const p) {
memset(p->literal_, 0, sizeof(p->literal_));
memset(p->red_, 0, sizeof(p->red_));