107 lines
2.7 KiB
Zig
107 lines
2.7 KiB
Zig
// SPDX-License-Identifier: MIT
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// Copyright (c) 2015-2020 Zig Contributors
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// This file is part of [zig](https://ziglang.org/), which is MIT licensed.
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// The MIT license requires this copyright notice to be included in all copies
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// and substantial portions of the software.
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// Ported from musl, which is licensed under the MIT license:
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// https://git.musl-libc.org/cgit/musl/tree/COPYRIGHT
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//
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// https://git.musl-libc.org/cgit/musl/tree/src/math/fabsf.c
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// https://git.musl-libc.org/cgit/musl/tree/src/math/fabs.c
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const std = @import("../std.zig");
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const math = std.math;
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const expect = std.testing.expect;
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const maxInt = std.math.maxInt;
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/// Returns the absolute value of x.
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///
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/// Special Cases:
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/// - fabs(+-inf) = +inf
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/// - fabs(nan) = nan
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pub fn fabs(x: anytype) @TypeOf(x) {
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const T = @TypeOf(x);
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return switch (T) {
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f16 => fabs16(x),
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f32 => fabs32(x),
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f64 => fabs64(x),
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f128 => fabs128(x),
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else => @compileError("fabs not implemented for " ++ @typeName(T)),
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};
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}
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fn fabs16(x: f16) f16 {
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var u = @bitCast(u16, x);
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u &= 0x7FFF;
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return @bitCast(f16, u);
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}
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fn fabs32(x: f32) f32 {
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var u = @bitCast(u32, x);
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u &= 0x7FFFFFFF;
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return @bitCast(f32, u);
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}
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fn fabs64(x: f64) f64 {
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var u = @bitCast(u64, x);
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u &= maxInt(u64) >> 1;
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return @bitCast(f64, u);
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}
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fn fabs128(x: f128) f128 {
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var u = @bitCast(u128, x);
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u &= maxInt(u128) >> 1;
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return @bitCast(f128, u);
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}
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test "math.fabs" {
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expect(fabs(@as(f16, 1.0)) == fabs16(1.0));
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expect(fabs(@as(f32, 1.0)) == fabs32(1.0));
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expect(fabs(@as(f64, 1.0)) == fabs64(1.0));
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expect(fabs(@as(f128, 1.0)) == fabs128(1.0));
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}
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test "math.fabs16" {
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expect(fabs16(1.0) == 1.0);
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expect(fabs16(-1.0) == 1.0);
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}
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test "math.fabs32" {
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expect(fabs32(1.0) == 1.0);
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expect(fabs32(-1.0) == 1.0);
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}
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test "math.fabs64" {
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expect(fabs64(1.0) == 1.0);
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expect(fabs64(-1.0) == 1.0);
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}
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test "math.fabs128" {
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expect(fabs128(1.0) == 1.0);
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expect(fabs128(-1.0) == 1.0);
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}
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test "math.fabs16.special" {
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expect(math.isPositiveInf(fabs(math.inf(f16))));
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expect(math.isPositiveInf(fabs(-math.inf(f16))));
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expect(math.isNan(fabs(math.nan(f16))));
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}
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test "math.fabs32.special" {
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expect(math.isPositiveInf(fabs(math.inf(f32))));
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expect(math.isPositiveInf(fabs(-math.inf(f32))));
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expect(math.isNan(fabs(math.nan(f32))));
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}
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test "math.fabs64.special" {
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expect(math.isPositiveInf(fabs(math.inf(f64))));
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expect(math.isPositiveInf(fabs(-math.inf(f64))));
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expect(math.isNan(fabs(math.nan(f64))));
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}
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test "math.fabs128.special" {
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expect(math.isPositiveInf(fabs(math.inf(f128))));
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expect(math.isPositiveInf(fabs(-math.inf(f128))));
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expect(math.isNan(fabs(math.nan(f128))));
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}
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