51 lines
1.1 KiB
Zig
51 lines
1.1 KiB
Zig
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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/// Returns whether x is negative or negative 0.
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pub fn signbit(x: var) bool {
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const T = @TypeOf(x);
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return switch (T) {
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f16 => signbit16(x),
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f32 => signbit32(x),
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f64 => signbit64(x),
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else => @compileError("signbit not implemented for " ++ @typeName(T)),
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};
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}
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fn signbit16(x: f16) bool {
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const bits = @bitCast(u16, x);
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return bits >> 15 != 0;
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}
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fn signbit32(x: f32) bool {
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const bits = @bitCast(u32, x);
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return bits >> 31 != 0;
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}
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fn signbit64(x: f64) bool {
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const bits = @bitCast(u64, x);
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return bits >> 63 != 0;
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}
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test "math.signbit" {
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expect(signbit(@as(f16, 4.0)) == signbit16(4.0));
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expect(signbit(@as(f32, 4.0)) == signbit32(4.0));
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expect(signbit(@as(f64, 4.0)) == signbit64(4.0));
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}
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test "math.signbit16" {
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expect(!signbit16(4.0));
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expect(signbit16(-3.0));
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}
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test "math.signbit32" {
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expect(!signbit32(4.0));
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expect(signbit32(-3.0));
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}
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test "math.signbit64" {
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expect(!signbit64(4.0));
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expect(signbit64(-3.0));
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}
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