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 "Test.h"
9#include "SkAutoPixmapStorage.h"
10#include "SkColor.h"
11#include "SkHalf.h"
12#include "SkOpts.h"
13#include "SkPixmap.h"
14#include "SkPM4f.h"
15#include "SkRandom.h"
16
17#include <cmath>
18
19static bool eq_within_half_float(float a, float b) {
20    const float kTolerance = 1.0f / (1 << (8 + 10));
21
22    SkHalf ha = SkFloatToHalf(a);
23    SkHalf hb = SkFloatToHalf(b);
24    float a2 = SkHalfToFloat(ha);
25    float b2 = SkHalfToFloat(hb);
26    return fabsf(a2 - b2) <= kTolerance;
27}
28
29static bool eq_within_half_float(const SkPM4f& a, const SkPM4f& b) {
30    for (int i = 0; i < 4; ++i) {
31        if (!eq_within_half_float(a.fVec[i], b.fVec[i])) {
32            return false;
33        }
34    }
35    return true;
36}
37
38DEF_TEST(color_half_float, reporter) {
39    const int w = 100;
40    const int h = 100;
41
42    SkImageInfo info = SkImageInfo::Make(w, h, kRGBA_F16_SkColorType, kPremul_SkAlphaType);
43
44    SkAutoPixmapStorage pm;
45    pm.alloc(info);
46    REPORTER_ASSERT(reporter, pm.computeByteSize() == SkToSizeT(w * h * sizeof(uint64_t)));
47
48    SkColor4f c4 { 1, 0.5f, 0.25f, 0.5f };
49    pm.erase(c4);
50
51    SkPM4f origpm4 = c4.premul();
52    for (int y = 0; y < pm.height(); ++y) {
53        for (int x = 0; x < pm.width(); ++x) {
54            SkPM4f pm4 = SkPM4f::FromF16(pm.addrF16(x, y));
55            REPORTER_ASSERT(reporter, eq_within_half_float(origpm4, pm4));
56        }
57    }
58}
59
60static bool is_denorm(uint16_t h) {
61    return (h & 0x7fff) < 0x0400;
62}
63
64static bool is_finite(uint16_t h) {
65    return (h & 0x7c00) != 0x7c00;
66}
67
68DEF_TEST(SkHalfToFloat_finite_ftz, r) {
69    for (uint32_t h = 0; h <= 0xffff; h++) {
70        if (!is_finite(h)) {
71            // _finite_ftz() only works for values that can be represented as a finite half float.
72            continue;
73        }
74
75        // _finite_ftz() may flush denorms to zero.  0.0f will compare == with both +0.0f and -0.0f.
76        float expected  = SkHalfToFloat(h),
77              alternate = is_denorm(h) ? 0.0f : expected;
78
79        float actual = SkHalfToFloat_finite_ftz(h)[0];
80
81        REPORTER_ASSERT(r, actual == expected || actual == alternate);
82    }
83}
84
85DEF_TEST(SkFloatToHalf_finite_ftz, r) {
86#if 0
87    for (uint64_t bits = 0; bits <= 0xffffffff; bits++) {
88#else
89    SkRandom rand;
90    for (int i = 0; i < 1000000; i++) {
91        uint32_t bits = rand.nextU();
92#endif
93        float f;
94        memcpy(&f, &bits, 4);
95
96        uint16_t expected = SkFloatToHalf(f);
97        if (!is_finite(expected)) {
98            // _finite_ftz() only works for values that can be represented as a finite half float.
99            continue;
100        }
101
102        uint16_t alternate = expected;
103        if (is_denorm(expected)) {
104            // _finite_ftz() may flush denorms to zero, and happens to keep the sign bit.
105            alternate = std::signbit(f) ? 0x8000 : 0x0000;
106        }
107
108        uint16_t actual = SkFloatToHalf_finite_ftz(Sk4f{f})[0];
109        // _finite_ftz() may truncate instead of rounding, so it may be one too small.
110        REPORTER_ASSERT(r, actual == expected  || actual == expected  - 1 ||
111                           actual == alternate || actual == alternate - 1);
112    }
113}
114