authorgravatar for jacobly@ziglang.orgJacob Young <jacobly@ziglang.org> 2023-05-10 13:20:13-04:00
committergravatar for jacobly@ziglang.orgJacob Young <jacobly@ziglang.org> 2023-05-10 15:16:50-04:00
log716d6a026f468cdb6b84a3e7f1004904b9ac6ecc
treeed51fea6f94d8c06702beace4ce50ec8c7dd5290
parentc5b96c7447efde0d10de9689f03d151afcafbad5

std: revert `comptime_float` support

Removed since I'm aware of some design considerations of `comptime_float`.

4 files changed, 21 insertions(+), 28 deletions(-)

lib/std/math.zig-1
......@@ -37,7 +37,6 @@ pub const sqrt2 = 1.414213562373095048801688724209698079;
3737/// 1/sqrt(2)
3838pub const sqrt1_2 = 0.707106781186547524400844362104849039;
3939
40pub const floatBits = @import("math/float.zig").floatBits;
4140pub const floatExponentBits = @import("math/float.zig").floatExponentBits;
4241pub const floatMantissaBits = @import("math/float.zig").floatMantissaBits;
4342pub const floatFractionalBits = @import("math/float.zig").floatFractionalBits;
lib/std/math/copysign.zig+7-8
......@@ -4,17 +4,16 @@ const expect = std.testing.expect;
44
55/// Returns a value with the magnitude of `magnitude` and the sign of `sign`.
66pub fn copysign(magnitude: anytype, sign: @TypeOf(magnitude)) @TypeOf(magnitude) {
7 const bits = math.floatBits(@TypeOf(magnitude));
8 const FBits = @Type(.{ .Float = .{ .bits = bits } });
9 const TBits = @Type(.{ .Int = .{ .signedness = .unsigned, .bits = bits } });
10 const sign_bit_mask = @as(TBits, 1) << (bits - 1);
11 const mag = @bitCast(TBits, @as(FBits, magnitude)) & ~sign_bit_mask;
12 const sgn = @bitCast(TBits, @as(FBits, sign)) & sign_bit_mask;
13 return @bitCast(FBits, mag | sgn);
7 const T = @TypeOf(magnitude);
8 const TBits = std.meta.Int(.unsigned, @typeInfo(T).Float.bits);
9 const sign_bit_mask = @as(TBits, 1) << (@bitSizeOf(T) - 1);
10 const mag = @bitCast(TBits, magnitude) & ~sign_bit_mask;
11 const sgn = @bitCast(TBits, sign) & sign_bit_mask;
12 return @bitCast(T, mag | sgn);
1413}
1514
1615test "math.copysign" {
17 inline for ([_]type{ f16, f32, f64, f80, f128, c_longdouble, comptime_float }) |T| {
16 inline for ([_]type{ f16, f32, f64, f80, f128 }) |T| {
1817 try expect(copysign(@as(T, 1.0), @as(T, 1.0)) == 1.0);
1918 try expect(copysign(@as(T, 2.0), @as(T, -2.0)) == -2.0);
2019 try expect(copysign(@as(T, -3.0), @as(T, 3.0)) == 3.0);
lib/std/math/float.zig+12-17
......@@ -4,29 +4,21 @@ const expect = std.testing.expect;
44
55/// Creates a raw "1.0" mantissa for floating point type T. Used to dedupe f80 logic.
66inline fn mantissaOne(comptime T: type) comptime_int {
7 return 1 << floatFractionalBits(T) & ((1 << floatMantissaBits(T)) - 1);
7 return if (@typeInfo(T).Float.bits == 80) 1 << floatFractionalBits(T) else 0;
88}
99
1010/// Creates floating point type T from an unbiased exponent and raw mantissa.
1111inline fn reconstructFloat(comptime T: type, comptime exponent: comptime_int, comptime mantissa: comptime_int) T {
12 const FBits = @Type(.{ .Float = .{ .bits = floatBits(T) } });
13 const TBits = @Type(.{ .Int = .{ .signedness = .unsigned, .bits = floatBits(T) } });
12 const TBits = @Type(.{ .Int = .{ .signedness = .unsigned, .bits = @bitSizeOf(T) } });
1413 const biased_exponent = @as(TBits, exponent + floatExponentMax(T));
15 return @bitCast(FBits, (biased_exponent << floatMantissaBits(T)) | @as(TBits, mantissa));
16}
17
18/// Returns the number of bits in floating point type T.
19pub inline fn floatBits(comptime T: type) comptime_int {
20 return switch (@typeInfo(T)) {
21 .Float => |info| info.bits,
22 .ComptimeFloat => 128,
23 else => @compileError(@typeName(T) ++ " is not a floating point type"),
24 };
14 return @bitCast(T, (biased_exponent << floatMantissaBits(T)) | @as(TBits, mantissa));
2515}
2616
2717/// Returns the number of bits in the exponent of floating point type T.
2818pub inline fn floatExponentBits(comptime T: type) comptime_int {
29 return switch (floatBits(T)) {
19 comptime assert(@typeInfo(T) == .Float);
20
21 return switch (@typeInfo(T).Float.bits) {
3022 16 => 5,
3123 32 => 8,
3224 64 => 11,
......@@ -38,7 +30,9 @@ pub inline fn floatExponentBits(comptime T: type) comptime_int {
3830
3931/// Returns the number of bits in the mantissa of floating point type T.
4032pub inline fn floatMantissaBits(comptime T: type) comptime_int {
41 return switch (floatBits(T)) {
33 comptime assert(@typeInfo(T) == .Float);
34
35 return switch (@typeInfo(T).Float.bits) {
4236 16 => 10,
4337 32 => 23,
4438 64 => 52,
......@@ -50,10 +44,12 @@ pub inline fn floatMantissaBits(comptime T: type) comptime_int {
5044
5145/// Returns the number of fractional bits in the mantissa of floating point type T.
5246pub inline fn floatFractionalBits(comptime T: type) comptime_int {
47 comptime assert(@typeInfo(T) == .Float);
48
5349 // standard IEEE floats have an implicit 0.m or 1.m integer part
5450 // f80 is special and has an explicitly stored bit in the MSB
5551 // this function corresponds to `MANT_DIG - 1' from C
56 return switch (floatBits(T)) {
52 return switch (@typeInfo(T).Float.bits) {
5753 16 => 10,
5854 32 => 23,
5955 64 => 52,
......@@ -105,7 +101,6 @@ test "float bits" {
105101 inline for ([_]type{ f16, f32, f64, f80, f128, c_longdouble }) |T| {
106102 // (1 +) for the sign bit, since it is separate from the other bits
107103 const size = 1 + floatExponentBits(T) + floatMantissaBits(T);
108 try expect(floatBits(T) == size);
109104 try expect(@bitSizeOf(T) == size);
110105
111106 // for machine epsilon, assert expmin <= -prec <= expmax
lib/std/math/nan.zig+2-2
......@@ -2,13 +2,13 @@ const math = @import("../math.zig");
22
33/// Returns the nan representation for type T.
44pub inline fn nan(comptime T: type) T {
5 return switch (math.floatBits(T)) {
5 return switch (@typeInfo(T).Float.bits) {
66 16 => math.nan_f16,
77 32 => math.nan_f32,
88 64 => math.nan_f64,
99 80 => math.nan_f80,
1010 128 => math.nan_f128,
11 else => @compileError("unknown floating point type " ++ @typeName(T)),
11 else => @compileError("unreachable"),
1212 };
1313}
1414