zig/lib/std/math/modf.zig
Alex Rønne Petersen 9ab7eec23e represent Mac Catalyst as aarch64-maccatalyst-none rather than aarch64-ios-macabi
Apple's own headers and tbd files prefer to think of Mac Catalyst as a distinct
OS target. Earlier, when DriverKit support was added to LLVM, it was represented
a distinct OS. So why Apple decided to only represent Mac Catalyst as an ABI in
the target triple is beyond me. But this isn't the first time they've ignored
established target triple norms (see: armv7k and aarch64_32) and it probably
won't be the last.

While doing this, I also audited all Darwin OS prongs throughout the codebase
and made sure they cover all the tags.
2025-11-14 11:33:35 +01:00

135 lines
4.5 KiB
Zig

const std = @import("../std.zig");
const builtin = @import("builtin");
const math = std.math;
const expect = std.testing.expect;
const expectEqual = std.testing.expectEqual;
const expectApproxEqAbs = std.testing.expectApproxEqAbs;
pub fn Modf(comptime T: type) type {
return struct {
fpart: T,
ipart: T,
};
}
/// Returns the integer and fractional floating-point numbers that sum to x. The sign of each
/// result is the same as the sign of x.
/// In comptime, may be used with comptime_float
///
/// Special Cases:
/// - modf(+-inf) = +-inf, nan
/// - modf(nan) = nan, nan
pub fn modf(x: anytype) Modf(@TypeOf(x)) {
const ipart = @trunc(x);
return .{
.ipart = ipart,
.fpart = x - ipart,
};
}
test modf {
inline for ([_]type{ f16, f32, f64, f80, f128 }) |T| {
const epsilon: comptime_float = @max(1e-6, math.floatEps(T));
var r: Modf(T) = undefined;
r = modf(@as(T, 1.0));
try expectEqual(1.0, r.ipart);
try expectEqual(0.0, r.fpart);
r = modf(@as(T, 0.34682));
try expectEqual(0.0, r.ipart);
try expectApproxEqAbs(@as(T, 0.34682), r.fpart, epsilon);
r = modf(@as(T, 2.54576));
try expectEqual(2.0, r.ipart);
try expectApproxEqAbs(0.54576, r.fpart, epsilon);
r = modf(@as(T, 3.9782));
try expectEqual(3.0, r.ipart);
try expectApproxEqAbs(0.9782, r.fpart, epsilon);
}
}
/// Generate a namespace of tests for modf on values of the given type
fn ModfTests(comptime T: type) type {
return struct {
test "normal" {
const epsilon: comptime_float = @max(1e-6, math.floatEps(T));
var r: Modf(T) = undefined;
r = modf(@as(T, 1.0));
try expectEqual(1.0, r.ipart);
try expectEqual(0.0, r.fpart);
r = modf(@as(T, 0.34682));
try expectEqual(0.0, r.ipart);
try expectApproxEqAbs(0.34682, r.fpart, epsilon);
r = modf(@as(T, 3.97812));
try expectEqual(3.0, r.ipart);
// account for precision error
const expected_a: T = 3.97812 - @as(T, 3);
try expectApproxEqAbs(expected_a, r.fpart, epsilon);
r = modf(@as(T, 43874.3));
try expectEqual(43874.0, r.ipart);
// account for precision error
const expected_b: T = 43874.3 - @as(T, 43874.0);
try expectApproxEqAbs(expected_b, r.fpart, epsilon);
r = modf(@as(T, 1234.340780));
try expectEqual(1234.0, r.ipart);
// account for precision error
const expected_c: T = 1234.340780 - @as(T, 1234);
try expectApproxEqAbs(expected_c, r.fpart, epsilon);
}
test "vector" {
if (builtin.os.tag.isDarwin() and builtin.cpu.arch == .aarch64) return error.SkipZigTest;
if (builtin.cpu.arch == .s390x) return error.SkipZigTest;
if (comptime builtin.cpu.has(.loongarch, .lsx)) return error.SkipZigTest; // https://github.com/llvm/llvm-project/issues/159529
const widths = [_]comptime_int{ 1, 2, 3, 4, 8, 16 };
inline for (widths) |len| {
const V: type = @Vector(len, T);
var r: Modf(V) = undefined;
r = modf(@as(V, @splat(1.0)));
try expectEqual(@as(V, @splat(1.0)), r.ipart);
try expectEqual(@as(V, @splat(0.0)), r.fpart);
r = modf(@as(V, @splat(2.75)));
try expectEqual(@as(V, @splat(2.0)), r.ipart);
try expectEqual(@as(V, @splat(0.75)), r.fpart);
r = modf(@as(V, @splat(0.2)));
try expectEqual(@as(V, @splat(0.0)), r.ipart);
try expectEqual(@as(V, @splat(0.2)), r.fpart);
r = modf(std.simd.iota(T, len) + @as(V, @splat(0.5)));
try expectEqual(std.simd.iota(T, len), r.ipart);
try expectEqual(@as(V, @splat(0.5)), r.fpart);
}
}
test "inf" {
var r: Modf(T) = undefined;
r = modf(math.inf(T));
try expect(math.isPositiveInf(r.ipart) and math.isNan(r.fpart));
r = modf(-math.inf(T));
try expect(math.isNegativeInf(r.ipart) and math.isNan(r.fpart));
}
test "nan" {
const r: Modf(T) = modf(math.nan(T));
try expect(math.isNan(r.ipart) and math.isNan(r.fpart));
}
};
}
comptime {
for ([_]type{ f16, f32, f64, f80, f128 }) |T| {
_ = ModfTests(T);
}
}