zig/std/math/isnormal.zig

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const std = @import("../index.zig");
const math = std.math;
const assert = std.debug.assert;
const maxInt = std.math.maxInt;
pub fn isNormal(x: var) bool {
const T = @typeOf(x);
switch (T) {
f16 => {
const bits = @bitCast(u16, x);
return (bits + 1024) & 0x7FFF >= 2048;
},
f32 => {
const bits = @bitCast(u32, x);
return (bits + 0x00800000) & 0x7FFFFFFF >= 0x01000000;
},
f64 => {
const bits = @bitCast(u64, x);
return (bits + (1 << 52)) & (maxInt(u64) >> 1) >= (1 << 53);
},
else => {
@compileError("isNormal not implemented for " ++ @typeName(T));
},
}
}
test "math.isNormal" {
assert(!isNormal(math.nan(f16)));
assert(!isNormal(math.nan(f32)));
assert(!isNormal(math.nan(f64)));
assert(!isNormal(f16(0)));
assert(!isNormal(f32(0)));
assert(!isNormal(f64(0)));
assert(isNormal(f16(1.0)));
assert(isNormal(f32(1.0)));
assert(isNormal(f64(1.0)));
}