skia2/bench/ColorPrivBench.cpp
mtklein a1ebeb25e9 Remove const from const int loops.
This drives me nuts, and prevents `while (loops --> 0)`.

BUG=skia:

Review URL: https://codereview.chromium.org/1379923005
2015-10-01 09:43:39 -07:00

88 lines
3.2 KiB
C++

/*
* Copyright 2013 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "Benchmark.h"
#include "SkColorPriv.h"
#include "SkRandom.h"
#include "SkString.h"
template <bool kFast, bool kScale>
class FourByteInterpBench : public Benchmark {
public:
FourByteInterpBench() {
fName.set("four_byte_interp");
fName.append(kFast ? "_fast" : "_slow");
fName.append(kScale ? "_255" : "_256");
}
bool isSuitableFor(Backend backend) override {
return backend == kNonRendering_Backend;
}
const char* onGetName() override { return fName.c_str(); }
void onDelayedSetup() override {
// A handful of random srcs and dsts.
SkRandom rand;
for (int i = 0; i < kInputs; i++) {
fSrcs[i] = SkPreMultiplyColor(rand.nextU());
fDsts[i] = SkPreMultiplyColor(rand.nextU());
}
// We'll exhaustively test all scales instead of using random numbers.
for (int i = 0; i <= 256; i++) {
fScales[i] = i;
}
if (kScale) fScales[256] = 255; // We'll just do 255 twice if we're limited to [0,255].
}
void onDraw(int loops, SkCanvas*) override {
// We xor results of FourByteInterp into junk to make sure the function runs.
volatile SkPMColor junk = 0;
for (int loop = 0; loop < loops; loop++) {
for (int i = 0; i < kInputs; i++) {
for (size_t j = 0; j <= 256; j++) {
// Note: we really want to load src and dst here and not outside in the i-loop.
// If we put the loads there, a clever compiler will do the not-insignificant
// work in the FourByteInterps that depends only on src and dst outside this
// loop, so we'd only be benchmarking the back half of those functions that also
// depends on scale. Even here, these must be volatile arrays to prevent that
// clever compiler from hoisting the loads out of the loop on its own.
const SkPMColor src = fSrcs[i];
const SkPMColor dst = fDsts[i];
const unsigned scale = fScales[j];
if (kFast && kScale) {
junk ^= SkFastFourByteInterp(src, dst, scale);
} else if (kFast) {
junk ^= SkFastFourByteInterp256(src, dst, scale);
} else if (kScale) {
junk ^= SkFourByteInterp(src, dst, scale);
} else {
junk ^= SkFourByteInterp256(src, dst, scale);
}
}
}
}
}
private:
SkString fName;
static const int kInputs = 10; // Arbitrary.
volatile unsigned fSrcs[kInputs];
volatile unsigned fDsts[kInputs];
unsigned fScales[257]; // We need space for [0, 256].
};
#define COMMA ,
DEF_BENCH(return (new FourByteInterpBench<true COMMA true>);)
DEF_BENCH(return (new FourByteInterpBench<true COMMA false>);)
DEF_BENCH(return (new FourByteInterpBench<false COMMA true>);)
DEF_BENCH(return (new FourByteInterpBench<false COMMA false>);)
#undef COMMA