lol/src/t/math/half.cpp

//
//  Lol Engine — Unit tests
//
//  Copyright © 2010—2014 Sam Hocevar <sam@hocevar.net>
//
//  Lol Engine is free software. It comes without any warranty, to
//  the extent permitted by applicable law. You can redistribute it
//  and/or modify it under the terms of the Do What the Fuck You Want
//  to Public License, Version 2, as published by the WTFPL Task Force.
//  See http://www.wtfpl.net/ for more details.
//

#include <lol/engine-internal.h>

#include <cmath>

#include <lolunit.h>

namespace lol
{

lolunit_declare_fixture(HalfTest)
{
    lolunit_declare_test(FloatToHalf)
    {
        for (size_t i = 0; i < sizeof(pairs) / sizeof(*pairs); i++)
        {
            half a = (half)pairs[i].f;
            uint16_t b = pairs[i].x;
            lolunit_set_context(i);
            lolunit_assert_equal(a.bits, b);
        }
    }

    lolunit_declare_test(FloatToHalfAccurate)
    {
        for (size_t i = 0; i < sizeof(pairs) / sizeof(*pairs); i++)
        {
            half a = half::makeaccurate(pairs[i].f);
            uint16_t b = pairs[i].x;
            lolunit_set_context(i);
            lolunit_assert_equal(a.bits, b);
        }
    }

    lolunit_declare_test(BitsToHalf)
    {
        for (unsigned int i = 0; i < 0x10000; i++)
        {
            half a = half::makebits(i);
            uint16_t b = i;
            lolunit_set_context(i);
            lolunit_assert_equal(a.bits, b);
        }
    }

    lolunit_declare_test(HalfIsNaN)
    {
        lolunit_assert(half::makebits(0x7c01).is_nan());
        lolunit_assert(half::makebits(0xfc01).is_nan());
        lolunit_assert(half::makebits(0x7e00).is_nan());
        lolunit_assert(half::makebits(0xfe00).is_nan());

        lolunit_assert(!half::makebits(0x7c00).is_nan());
        lolunit_assert(!half::makebits(0xfc00).is_nan());

        lolunit_assert(!half(0.0f).is_nan());
        lolunit_assert(!half(-0.0f).is_nan());
        lolunit_assert(!half(2.0f).is_nan());
        lolunit_assert(!half(-2.0f).is_nan());
    }

    lolunit_declare_test(HalfIsInf)
    {
        lolunit_assert(half(65536.0f).is_inf());
        lolunit_assert(half(-65536.0f).is_inf());

        lolunit_assert(!half(0.0f).is_inf());
        lolunit_assert(!half(-0.0f).is_inf());
        lolunit_assert(!half(65535.0f).is_inf());
        lolunit_assert(!half(-65535.0f).is_inf());

        lolunit_assert(half::makebits(0x7c00).is_inf());
        lolunit_assert(half::makebits(0xfc00).is_inf());

        lolunit_assert(!half::makebits(0x7e00).is_inf());
        lolunit_assert(!half::makebits(0xfe00).is_inf());
    }

    lolunit_declare_test(HalfIsFinite)
    {
        lolunit_assert(half(0.0f).is_finite());
        lolunit_assert(half(-0.0f).is_finite());
        lolunit_assert(half(65535.0f).is_finite());
        lolunit_assert(half(-65535.0f).is_finite());

        lolunit_assert(!half(65536.0f).is_finite());
        lolunit_assert(!half(-65536.0f).is_finite());

        lolunit_assert(!half::makebits(0x7c00).is_finite());
        lolunit_assert(!half::makebits(0xfc00).is_finite());

        lolunit_assert(!half::makebits(0x7e00).is_finite());
        lolunit_assert(!half::makebits(0xfe00).is_finite());
    }

    lolunit_declare_test(HalfIsNormal)
    {
        lolunit_assert(half(0.0f).is_normal());
        lolunit_assert(half(-0.0f).is_normal());
        lolunit_assert(half(65535.0f).is_normal());
        lolunit_assert(half(-65535.0f).is_normal());

        lolunit_assert(!half(65536.0f).is_normal());
        lolunit_assert(!half(-65536.0f).is_normal());

        lolunit_assert(!half::makebits(0x7c00).is_normal());
        lolunit_assert(!half::makebits(0xfc00).is_normal());

        lolunit_assert(!half::makebits(0x7e00).is_normal());
        lolunit_assert(!half::makebits(0xfe00).is_normal());
    }

    lolunit_declare_test(HalfClassify)
    {
        for (uint32_t i = 0; i < 0x10000; i++)
        {
            lolunit_set_context(i);
            half h = half::makebits(i);
            if (h.is_nan())
            {
                lolunit_assert(!h.is_inf());
                lolunit_assert(!h.is_normal());
                lolunit_assert(!h.is_finite());
            }
            else if (h.is_inf())
            {
                lolunit_assert(!h.is_normal());
                lolunit_assert(!h.is_finite());
            }
            else
            {
                lolunit_assert(h.is_finite());
            }
        }
    }

    lolunit_declare_test(HalfToFloat)
    {
        for (size_t i = 0; i < sizeof(pairs) / sizeof(*pairs); i++)
        {
            float a = (float)half::makebits(pairs[i].x);
            float b = pairs[i].f;
            lolunit_set_context(i);
            lolunit_assert_equal(a, b);
        }

        for (uint32_t i = 0; i < 0x10000; i++)
        {
            half h = half::makebits(i);
            if (h.is_nan())
                continue;

            float f = (float)h;
            half g = (half)f;
            lolunit_set_context(i);
            lolunit_assert_equal(g.bits, h.bits);
        }
    }

    lolunit_declare_test(HalfToInt)
    {
        lolunit_assert_equal((int)(half)(0.0f), 0);
        lolunit_assert_equal((int)(half)(-0.0f), 0);
        lolunit_assert_equal((int)(half)(0.9f), 0);
        lolunit_assert_equal((int)(half)(-0.9f), 0);
        lolunit_assert_equal((int)(half)(1.0f), 1);
        lolunit_assert_equal((int)(half)(-1.0f), -1);
        lolunit_assert_equal((int)(half)(1.9f), 1);
        lolunit_assert_equal((int)(half)(-1.9f), -1);
        lolunit_assert_equal((int)(half)(65504.0f), 65504);
        lolunit_assert_equal((int)(half)(-65504.0f), -65504);
    }

    lolunit_declare_test(FloatOpHalf)
    {
        half zero = 0;
        half one = 1;
        half two = 2;

        float a = zero + one;
        lolunit_assert_equal(1.0f, a);
        a += zero;
        lolunit_assert_equal(1.0f, a);
        a -= zero;
        lolunit_assert_equal(1.0f, a);
        a *= one;
        lolunit_assert_equal(1.0f, a);
        a /= one;
        lolunit_assert_equal(1.0f, a);

        float b = one + zero;
        lolunit_assert_equal(1.0f, b);
        b += one;
        lolunit_assert_equal(2.0f, b);
        b *= two;
        lolunit_assert_equal(4.0f, b);
        b -= two;
        lolunit_assert_equal(2.0f, b);
        b /= two;
        lolunit_assert_equal(1.0f, b);

        float c = one - zero;
        lolunit_assert_equal(1.0f, c);

        float d = two - one;
        lolunit_assert_equal(1.0f, d);

        float e = two + (-one);
        lolunit_assert_equal(1.0f, e);

        float f = (two * two) / (one + one);
        lolunit_assert_equal(2.0f, f);
    }

    lolunit_declare_test(HalfOpFloat)
    {
        half zero = 0;
        half one = 1;
        half two = 2;
        half four = 4;

        half a = one + 0.0f;
        lolunit_assert_equal(one.bits, a.bits);
        a += 0.0f;
        lolunit_assert_equal(one.bits, a.bits);
        a -= 0.0f;
        lolunit_assert_equal(one.bits, a.bits);
        a *= 1.0f;
        lolunit_assert_equal(one.bits, a.bits);
        a /= 1.0f;
        lolunit_assert_equal(one.bits, a.bits);

        half b = one + 0.0f;
        lolunit_assert_equal(one.bits, b.bits);
        b += 1.0f;
        lolunit_assert_equal(two.bits, b.bits);
        b *= 2.0f;
        lolunit_assert_equal(four.bits, b.bits);
        b -= 2.0f;
        lolunit_assert_equal(two.bits, b.bits);
        b /= 2.0f;
        lolunit_assert_equal(one.bits, b.bits);

        half c = 1.0f - zero;
        lolunit_assert_equal(one.bits, c.bits);

        half d = 2.0f - one;
        lolunit_assert_equal(one.bits, d.bits);

        half e = 2.0f + (-one);
        lolunit_assert_equal(one.bits, e.bits);

        half f = (2.0f * two) / (1.0f + one);
        lolunit_assert_equal(two.bits, f.bits);
    }

    struct TestPair { float f; uint16_t x; };

    static TestPair const pairs[11];
};

HalfTest::TestPair const HalfTest::pairs[] =
{
    /* All these values have exact half representations */
    { 0.0f,      0x0000 },
    { -0.0f,     0x8000 }, /* negative zero */
    { 1.0f,      0x3c00 },
    { -1.0f,     0xbc00 },
    { 2.0f,      0x4000 },
    { 0.5f,      0x3800 },
    { 0.125f,    0x3000 },
    { 15.9375f,  0x4bf8 },
    { 31.0f / (1 << 14), 0x17c0 }, /* 0x1.fp-10 */
    { 31.0f / (1 << 18), 0x07c0 }, /* 0x1.fp-14, normal float, denormal half */
    { 31.0f / (1 << 19), 0x03e0 }, /* 0x1.fp-15, normal float, denormal half */
};

} /* namespace lol */