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27 lines
1.2 KiB
Zig
27 lines
1.2 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 a value with the magnitude of `magnitude` and the sign of `sign`.
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pub fn copysign(magnitude: anytype, sign: @TypeOf(magnitude)) @TypeOf(magnitude) {
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const bits = math.floatBits(@TypeOf(magnitude));
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const FBits = @Type(.{ .Float = .{ .bits = bits } });
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const TBits = @Type(.{ .Int = .{ .signedness = .unsigned, .bits = bits } });
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const sign_bit_mask = @as(TBits, 1) << (bits - 1);
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const mag = @bitCast(TBits, @as(FBits, magnitude)) & ~sign_bit_mask;
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const sgn = @bitCast(TBits, @as(FBits, sign)) & sign_bit_mask;
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return @bitCast(FBits, mag | sgn);
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}
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test "math.copysign" {
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inline for ([_]type{ f16, f32, f64, f80, f128, c_longdouble, comptime_float }) |T| {
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try expect(copysign(@as(T, 1.0), @as(T, 1.0)) == 1.0);
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try expect(copysign(@as(T, 2.0), @as(T, -2.0)) == -2.0);
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try expect(copysign(@as(T, -3.0), @as(T, 3.0)) == 3.0);
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try expect(copysign(@as(T, -4.0), @as(T, -4.0)) == -4.0);
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try expect(copysign(@as(T, 5.0), @as(T, -500.0)) == -5.0);
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try expect(copysign(math.inf(T), @as(T, -0.0)) == -math.inf(T));
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try expect(copysign(@as(T, 6.0), -math.nan(T)) == -6.0);
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}
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}
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