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| 1 /* | |
| 2 * Copyright 2016 Google Inc. | |
| 3 * | |
| 4 * Use of this source code is governed by a BSD-style license that can be | |
| 5 * found in the LICENSE file. | |
| 6 */ | |
| 7 | |
| 8 #include "Fuzz.h" | |
| 9 #include <stdlib.h> | |
| 10 | |
| 11 // This really is just an example Fuzz*.cpp file. | |
| 12 // It tests that two different ways of calculating the Paeth predictor function
are equivalent. | |
| 13 | |
| 14 static uint8_t paeth_std(uint8_t a, uint8_t b, uint8_t c) { | |
| 15 int p = a+b-c; | |
| 16 | |
| 17 int pa = abs(p-a), | |
| 18 pb = abs(p-b), | |
| 19 pc = abs(p-c); | |
| 20 | |
| 21 if (pb < pa) { pa = pb; a = b; } | |
| 22 if (pc < pa) { a = c; } | |
| 23 return a; | |
| 24 } | |
| 25 | |
| 26 static uint8_t paeth_alt(uint8_t a, uint8_t b, uint8_t c) { | |
| 27 int min = SkTMin(a,b), | |
| 28 max = SkTMax(a,b); | |
| 29 int delta = (max-min)/3; | |
| 30 | |
| 31 if (c <= min+delta) return max; | |
| 32 if (c >= max-delta) return min; | |
| 33 return c; | |
| 34 } | |
| 35 | |
| 36 DEF_FUZZ(Paeth, fuzz) { | |
| 37 auto a = fuzz->nextB(), | |
| 38 b = fuzz->nextB(), | |
| 39 c = fuzz->nextB(); | |
| 40 SkDebugf("Paeth(%d,%d,%d)\n", a,b,c); | |
| 41 | |
| 42 if (a == b && b == c) { | |
| 43 fuzz->signalBoring(); // Not really boring, just demoing signalBoring()
. | |
| 44 } | |
| 45 | |
| 46 if (paeth_alt(a,b,c) != paeth_std(a,b,c)) { | |
| 47 fuzz->signalBug(); | |
| 48 } | |
| 49 } | |
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