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checkpoint for 8->5 bit reduction

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git-svn-id: http://skia.googlecode.com/svn/trunk@1362 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
reed@google.com 2011-05-18 13:07:22 +00:00
parent 9e39bb3603
commit 79b3b7e916
1 changed files with 70 additions and 0 deletions
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70
samplecode/SampleColorFilter.cpp
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@ -6,6 +6,74 @@
#include "SkPaint.h"
#include "SkShader.h"
static int inflate5To8(int x) {
return (x << 3) | (x >> 2);
}
static int trunc5(int x) {
return x >> 3;
}
#define SK_R16_BITS 5
static int round5_slow(int x) {
int orig = x & 7;
int fake = x >> 5;
int trunc = x >> 3;
int diff = fake - orig;
int bias = 0;
if (diff > 4) {
bias = -1;
} else if (diff < -4) {
bias = 1;
}
return trunc + bias;
}
static int round5_fast(int x) {
int result = x + 3 - (x >> 5) + (x >> 7);
result >>= 3;
{
int r2 = round5_slow(x);
SkASSERT(r2 == result);
}
return result;
}
static void test_5bits() {
int e0 = 0;
int e1 = 0;
int e2 = 0;
int ae0 = 0;
int ae1 = 0;
int ae2 = 0;
for (int i = 0; i < 256; i++) {
int t0 = trunc5(i);
int t1 = round5_fast(i);
int t2 = trunc5(i);
int v0 = inflate5To8(t0);
int v1 = inflate5To8(t1);
int v2 = inflate5To8(t2);
int err0 = i - v0;
int err1 = i - v1;
int err2 = i - v2;
SkDebugf("--- %3d : trunc=%3d (%2d) round:%3d (%2d) \n"/*new:%d (%2d)\n"*/, i,
v0, err0, v1, err1, v2, err2);
e0 += err0;
e1 += err1;
e2 += err2;
ae0 += SkAbs32(err0);
ae1 += SkAbs32(err1);
ae2 += SkAbs32(err2);
}
SkDebugf("--- trunc: %d %d round: %d %d new: %d %d\n", e0, ae0, e1, ae1, e2, ae2);
}
static SkShader* createChecker() {
SkBitmap bm;
bm.setConfig(SkBitmap::kARGB_8888_Config, 2, 2);
@ -57,6 +125,8 @@ public:
ColorFilterView() {
fBitmap = createBitmap(N);
fShader = createChecker();
// test_5bits();
}
virtual ~ColorFilterView() {