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const std = @import("../std.zig");
const math = std.math;
const expect = std.testing.expect;
const maxInt = std.math.maxInt;
// Returns whether x has a normalized representation (i.e. integer part of mantissa is 1).
pub fn isNormal(x: anytype) bool {
const T = @TypeOf(x);
switch (T) {
f16 => {
const bits = @bitCast(u16, x);
return (bits +% (1 << 10)) & (maxInt(u16) >> 1) >= (1 << 11);
},
f32 => {
const bits = @bitCast(u32, x);
return (bits +% (1 << 23)) & (maxInt(u32) >> 1) >= (1 << 24);
},
f64 => {
const bits = @bitCast(u64, x);
return (bits +% (1 << 52)) & (maxInt(u64) >> 1) >= (1 << 53);
},
f128 => {
const bits = @bitCast(u128, x);
return (bits +% (1 << 112)) & (maxInt(u128) >> 1) >= (1 << 113);
},
else => {
@compileError("isNormal not implemented for " ++ @typeName(T));
},
}
}
test "math.isNormal" {
try expect(!isNormal(math.nan(f16)));
try expect(!isNormal(math.nan(f32)));
try expect(!isNormal(math.nan(f64)));
try expect(!isNormal(math.nan(f128)));
try expect(!isNormal(-math.nan(f16)));
try expect(!isNormal(-math.nan(f32)));
try expect(!isNormal(-math.nan(f64)));
try expect(!isNormal(-math.nan(f128)));
try expect(!isNormal(math.inf(f16)));
try expect(!isNormal(math.inf(f32)));
try expect(!isNormal(math.inf(f64)));
try expect(!isNormal(math.inf(f128)));
try expect(!isNormal(-math.inf(f16)));
try expect(!isNormal(-math.inf(f32)));
try expect(!isNormal(-math.inf(f64)));
try expect(!isNormal(-math.inf(f128)));
try expect(!isNormal(@as(f16, 0)));
try expect(!isNormal(@as(f32, 0)));
try expect(!isNormal(@as(f64, 0)));
try expect(!isNormal(@as(f128, 0)));
try expect(isNormal(@as(f16, 1.0)));
try expect(isNormal(@as(f32, 1.0)));
try expect(isNormal(@as(f64, 1.0)));
try expect(isNormal(@as(f128, 1.0)));
}
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