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std.math.isFinite: make generic, support f80

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viri 2022-04-07 01:24:46 -06:00
parent 289ba5dfc2
commit a2f5f0da5c
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1 changed files with 29 additions and 45 deletions
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74
lib/std/math/isfinite.zig
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@ -1,59 +1,43 @@
const std = @import("../std.zig");
const math = std.math;
const expect = std.testing.expect;
const maxInt = std.math.maxInt;
/// Returns whether x is a finite value.
pub fn isFinite(x: anytype) bool {
const T = @TypeOf(x);
switch (T) {
f16 => {
const bits = @bitCast(u16, x);
return bits & 0x7FFF < 0x7C00;
},
f32 => {
const bits = @bitCast(u32, x);
return bits & 0x7FFFFFFF < 0x7F800000;
},
f64 => {
const bits = @bitCast(u64, x);
return bits & (maxInt(u64) >> 1) < (0x7FF << 52);
},
f128 => {
const bits = @bitCast(u128, x);
return bits & (maxInt(u128) >> 1) < (0x7FFF << 112);
},
else => {
@compileError("isFinite not implemented for " ++ @typeName(T));
},
const TBits = std.meta.Int(.unsigned, @bitSizeOf(T));
if (@typeInfo(T) != .Float) {
@compileError("isFinite not implemented for " ++ @typeName(T));
}
const exponent_bits = math.floatExponentBits(T);
const mantissa_bits = math.floatMantissaBits(T);
const all1s_exponent = ((1 << exponent_bits) - 1) << mantissa_bits;
const remove_sign = ~@as(TBits, 0) >> 1;
return @bitCast(TBits, x) & remove_sign < all1s_exponent;
}
test "math.isFinite" {
try expect(isFinite(@as(f16, 0.0)));
try expect(isFinite(@as(f16, -0.0)));
try expect(isFinite(@as(f32, 0.0)));
try expect(isFinite(@as(f32, -0.0)));
try expect(isFinite(@as(f64, 0.0)));
try expect(isFinite(@as(f64, -0.0)));
try expect(isFinite(@as(f128, 0.0)));
try expect(isFinite(@as(f128, -0.0)));
// TODO remove when #11391 is resolved
if (@import("builtin").os.tag == .freebsd) return error.SkipZigTest;
try expect(!isFinite(math.inf(f16)));
try expect(!isFinite(-math.inf(f16)));
try expect(!isFinite(math.inf(f32)));
try expect(!isFinite(-math.inf(f32)));
try expect(!isFinite(math.inf(f64)));
try expect(!isFinite(-math.inf(f64)));
try expect(!isFinite(math.inf(f128)));
try expect(!isFinite(-math.inf(f128)));
inline for ([_]type{ f16, f32, f64, f80, f128 }) |T| {
// normals
try expect(isFinite(@as(T, 1.0)));
try expect(isFinite(-@as(T, 1.0)));
try expect(!isFinite(math.nan(f16)));
try expect(!isFinite(-math.nan(f16)));
try expect(!isFinite(math.nan(f32)));
try expect(!isFinite(-math.nan(f32)));
try expect(!isFinite(math.nan(f64)));
try expect(!isFinite(-math.nan(f64)));
try expect(!isFinite(math.nan(f128)));
try expect(!isFinite(-math.nan(f128)));
// zero & subnormals
try expect(isFinite(@as(T, 0.0)));
try expect(isFinite(@as(T, -0.0)));
try expect(isFinite(math.floatTrueMin(T)));
// other float limits
try expect(isFinite(math.floatMin(T)));
try expect(isFinite(math.floatMax(T)));
// inf & nan
try expect(!isFinite(math.inf(T)));
try expect(!isFinite(-math.inf(T)));
try expect(!isFinite(math.nan(T)));
try expect(!isFinite(-math.nan(T)));
}
}