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612ad779bb
* std: fix overflow in math.scalbn32 * std: rewrite math.scalbn to be generic * std: support f128 in math.isNormal * std: enable f128 tests in math.scalbn
51 lines
1.7 KiB
Zig
51 lines
1.7 KiB
Zig
// SPDX-License-Identifier: MIT
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// Copyright (c) 2015-2021 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 has a normalized representation (i.e. integer part of mantissa is 1).
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pub fn isNormal(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 + (1 << 10)) & (maxInt(u16) >> 1) >= (1 << 11);
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},
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f32 => {
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const bits = @bitCast(u32, x);
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return (bits + (1 << 23)) & (maxInt(u32) >> 1) >= (1 << 24);
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},
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f64 => {
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const bits = @bitCast(u64, x);
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return (bits + (1 << 52)) & (maxInt(u64) >> 1) >= (1 << 53);
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},
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f128 => {
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const bits = @bitCast(u128, x);
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return (bits + (1 << 112)) & (maxInt(u128) >> 1) >= (1 << 113);
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},
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else => {
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@compileError("isNormal not implemented for " ++ @typeName(T));
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},
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}
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}
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test "math.isNormal" {
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try expect(!isNormal(math.nan(f16)));
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try expect(!isNormal(math.nan(f32)));
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try expect(!isNormal(math.nan(f64)));
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try expect(!isNormal(math.nan(f128)));
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try expect(!isNormal(@as(f16, 0)));
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try expect(!isNormal(@as(f32, 0)));
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try expect(!isNormal(@as(f64, 0)));
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try expect(!isNormal(@as(f128, 0)));
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try expect(isNormal(@as(f16, 1.0)));
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try expect(isNormal(@as(f32, 1.0)));
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try expect(isNormal(@as(f64, 1.0)));
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try expect(isNormal(@as(f128, 1.0)));
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}
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