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d29871977f
We already have a LICENSE file that covers the Zig Standard Library. We no longer need to remind everyone that the license is MIT in every single file. Previously this was introduced to clarify the situation for a fork of Zig that made Zig's LICENSE file harder to find, and replaced it with their own license that required annual payments to their company. However that fork now appears to be dead. So there is no need to reinforce the copyright notice in every single file.
36 lines
993 B
Zig
36 lines
993 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 math.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 math.exp(x - kln2) * scale * scale;
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}
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