39 lines
1.1 KiB
Zig
39 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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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: var) 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 + 1024) & 0x7FFF >= 2048;
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},
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f32 => {
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const bits = @bitCast(u32, x);
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return (bits + 0x00800000) & 0x7FFFFFFF >= 0x01000000;
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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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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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expect(!isNormal(math.nan(f16)));
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expect(!isNormal(math.nan(f32)));
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expect(!isNormal(math.nan(f64)));
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expect(!isNormal(f16(0)));
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expect(!isNormal(f32(0)));
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expect(!isNormal(f64(0)));
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expect(isNormal(f16(1.0)));
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expect(isNormal(f32(1.0)));
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expect(isNormal(f64(1.0)));
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}
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