47 lines
1.5 KiB
Zig
47 lines
1.5 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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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 whether x is a finite value.
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pub fn isFinite(x: anytype) bool {
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const T = @TypeOf(x);
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switch (T) {
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f16 => {
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const bits = @bitCast(u16, x);
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return bits & 0x7FFF < 0x7C00;
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},
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f32 => {
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const bits = @bitCast(u32, x);
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return bits & 0x7FFFFFFF < 0x7F800000;
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},
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f64 => {
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const bits = @bitCast(u64, x);
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return bits & (maxInt(u64) >> 1) < (0x7FF << 52);
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},
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else => {
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@compileError("isFinite not implemented for " ++ @typeName(T));
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},
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}
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}
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test "math.isFinite" {
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expect(isFinite(@as(f16, 0.0)));
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expect(isFinite(@as(f16, -0.0)));
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expect(isFinite(@as(f32, 0.0)));
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expect(isFinite(@as(f32, -0.0)));
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expect(isFinite(@as(f64, 0.0)));
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expect(isFinite(@as(f64, -0.0)));
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expect(!isFinite(math.inf(f16)));
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expect(!isFinite(-math.inf(f16)));
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expect(!isFinite(math.inf(f32)));
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expect(!isFinite(-math.inf(f32)));
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expect(!isFinite(math.inf(f64)));
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expect(!isFinite(-math.inf(f64)));
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}
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