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const std = @import("../std.zig");
const builtin = @import("builtin");
const math = std.math;
const meta = std.meta;
const expect = std.testing.expect;
pub fn isNan(x: anytype) bool {
return x != x;
}
/// TODO: LLVM is known to miscompile on some architectures to quiet NaN -
/// this is tracked by https://github.com/ziglang/zig/issues/14366
pub fn isSignalNan(x: anytype) bool {
const T = @TypeOf(x);
const U = meta.Int(.unsigned, @bitSizeOf(T));
const quiet_signal_bit_mask = 1 << (math.floatFractionalBits(T) - 1);
return isNan(x) and (@as(U, @bitCast(x)) & quiet_signal_bit_mask == 0);
}
test isNan {
inline for ([_]type{ f16, f32, f64, f80, f128, c_longdouble }) |T| {
try expect(isNan(math.nan(T)));
try expect(isNan(-math.nan(T)));
try expect(isNan(math.snan(T)));
try expect(!isNan(@as(T, 1.0)));
try expect(!isNan(@as(T, math.inf(T))));
}
}
test isSignalNan {
inline for ([_]type{ f16, f32, f64, f80, f128, c_longdouble }) |T| {
// TODO: Signalling NaN values get converted to quiet NaN values in
// some cases where they shouldn't such that this can fail.
// See https://github.com/ziglang/zig/issues/14366
// try expect(isSignalNan(math.snan(T)));
try expect(!isSignalNan(math.nan(T)));
try expect(!isSignalNan(@as(T, 1.0)));
try expect(!isSignalNan(math.inf(T)));
}
}
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