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41dd2beaac
* unify the logic for exporting math functions from compiler-rt,
with the appropriate suffixes and prefixes.
- add all missing f128 and f80 exports. Functions with missing
implementations call other functions and have TODO comments.
- also add f16 functions
* move math functions from freestanding libc to compiler-rt (#7265)
* enable all the f128 and f80 code in the stage2 compiler and behavior
tests (#11161).
* update std lib to use builtins rather than `std.math`.
36 lines
985 B
Zig
36 lines
985 B
Zig
// Ported from musl, which is licensed under the MIT license:
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// https://git.musl-libc.org/cgit/musl/tree/COPYRIGHT
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//
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// https://git.musl-libc.org/cgit/musl/tree/src/math/__expo2f.c
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// https://git.musl-libc.org/cgit/musl/tree/src/math/__expo2.c
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const math = @import("../math.zig");
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/// Returns exp(x) / 2 for x >= log(maxFloat(T)).
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pub fn expo2(x: anytype) @TypeOf(x) {
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const T = @TypeOf(x);
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return switch (T) {
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f32 => expo2f(x),
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f64 => expo2d(x),
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else => @compileError("expo2 not implemented for " ++ @typeName(T)),
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};
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}
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fn expo2f(x: f32) f32 {
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const k: u32 = 235;
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const kln2 = 0x1.45C778p+7;
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const u = (0x7F + k / 2) << 23;
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const scale = @bitCast(f32, u);
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return @exp(x - kln2) * scale * scale;
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}
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fn expo2d(x: f64) f64 {
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const k: u32 = 2043;
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const kln2 = 0x1.62066151ADD8BP+10;
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const u = (0x3FF + k / 2) << 20;
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const scale = @bitCast(f64, @as(u64, u) << 32);
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return @exp(x - kln2) * scale * scale;
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}
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