xref: /third_party/skia/tests/SkFixed15Test.cpp (revision cb93a386)
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 "src/core/SkFixed15.h"
9#include "tests/Test.h"
10
11DEF_TEST(SkFixed15, r) {
12    // For all v, v*0 == 0, v*1 == v.
13    for (uint16_t bits = 0; bits <= 32768; bits++) {
14        auto v = SkFixed15::Load(bits);
15        REPORTER_ASSERT(r, v * 0.0f == 0.0f);
16        REPORTER_ASSERT(r, v * 1.0f == v);
17    }
18
19    // Division and multiplication by powers of 2 is exact.
20    SkFixed15 v = 1.0f;
21    REPORTER_ASSERT(r, (v>>1)    == 0.50f);
22    REPORTER_ASSERT(r, (v>>2)    == 0.25f);
23    REPORTER_ASSERT(r, (v>>2<<1) == 0.50f);
24
25    // FromU8() should be just as good as going through float.
26    for (int x = 0; x < 256; x++) {
27        REPORTER_ASSERT(r, SkFixed15::FromU8(x) == SkFixed15(x * (1/255.0f)));
28    }
29
30    // to_u8() and FromU8() should roundtrip all bytes.
31    for (int x = 0; x < 256; x++) {
32        REPORTER_ASSERT(r, x == SkFixed15::FromU8(x).to_u8());
33    }
34}
35