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 "SkAutoPixmapStorage.h"
9 #include "SkColor.h"
10 #include "SkHalf.h"
11 #include "SkOpts.h"
12 #include "SkPixmap.h"
13 #include "SkRandom.h"
14 #include "SkTo.h"
15 #include "Test.h"
16
17 #include <cmath>
18
is_denorm(uint16_t h)19 static bool is_denorm(uint16_t h) {
20 return (h & 0x7fff) < 0x0400;
21 }
22
is_finite(uint16_t h)23 static bool is_finite(uint16_t h) {
24 return (h & 0x7c00) != 0x7c00;
25 }
26
DEF_TEST(SkHalfToFloat_finite_ftz,r)27 DEF_TEST(SkHalfToFloat_finite_ftz, r) {
28 for (uint32_t h = 0; h <= 0xffff; h++) {
29 if (!is_finite(h)) {
30 // _finite_ftz() only works for values that can be represented as a finite half float.
31 continue;
32 }
33
34 // _finite_ftz() may flush denorms to zero. 0.0f will compare == with both +0.0f and -0.0f.
35 float expected = SkHalfToFloat(h),
36 alternate = is_denorm(h) ? 0.0f : expected;
37
38 float actual = SkHalfToFloat_finite_ftz(h)[0];
39
40 REPORTER_ASSERT(r, actual == expected || actual == alternate);
41 }
42 }
43
DEF_TEST(SkFloatToHalf_finite_ftz,r)44 DEF_TEST(SkFloatToHalf_finite_ftz, r) {
45 #if 0
46 for (uint64_t bits = 0; bits <= 0xffffffff; bits++) {
47 #else
48 SkRandom rand;
49 for (int i = 0; i < 1000000; i++) {
50 uint32_t bits = rand.nextU();
51 #endif
52 float f;
53 memcpy(&f, &bits, 4);
54
55 uint16_t expected = SkFloatToHalf(f);
56 if (!is_finite(expected)) {
57 // _finite_ftz() only works for values that can be represented as a finite half float.
58 continue;
59 }
60
61 uint16_t alternate = expected;
62 if (is_denorm(expected)) {
63 // _finite_ftz() may flush denorms to zero, and happens to keep the sign bit.
64 alternate = std::signbit(f) ? 0x8000 : 0x0000;
65 }
66
67 uint16_t actual = SkFloatToHalf_finite_ftz(Sk4f{f})[0];
68 // _finite_ftz() may truncate instead of rounding, so it may be one too small.
69 REPORTER_ASSERT(r, actual == expected || actual == expected - 1 ||
70 actual == alternate || actual == alternate - 1);
71 }
72 }
73