ec95e00e28
stage2: change logic for detecting whether the main package is inside
the std package. Previously it relied on realpath() which is not portable.
This uses resolve() which is how imports already work.
* stage2: fix cleanup bug when creating Module
* flatten lib/std/special/* to lib/*
- this was motivated by making main_pkg_is_inside_std false for
compiler_rt & friends.
* rename "mini libc" to "universal libc"
71 lines
2.2 KiB
Zig
71 lines
2.2 KiB
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/__rem_pio2f.c
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const std = @import("std");
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const rem_pio2_large = @import("rem_pio2_large.zig").rem_pio2_large;
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const math = std.math;
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const toint = 1.5 / math.floatEps(f64);
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// pi/4
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const pio4 = 0x1.921fb6p-1;
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// invpio2: 53 bits of 2/pi
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const invpio2 = 6.36619772367581382433e-01; // 0x3FE45F30, 0x6DC9C883
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// pio2_1: first 25 bits of pi/2
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const pio2_1 = 1.57079631090164184570e+00; // 0x3FF921FB, 0x50000000
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// pio2_1t: pi/2 - pio2_1
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const pio2_1t = 1.58932547735281966916e-08; // 0x3E5110b4, 0x611A6263
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// Returns the remainder of x rem pi/2 in *y
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// use double precision for everything except passing x
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// use rem_pio2_large() for large x
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pub fn rem_pio2f(x: f32, y: *f64) i32 {
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var tx: [1]f64 = undefined;
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var ty: [1]f64 = undefined;
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var @"fn": f64 = undefined;
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var ix: u32 = undefined;
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var n: i32 = undefined;
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var sign: bool = undefined;
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var e0: u32 = undefined;
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var ui: u32 = undefined;
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ui = @bitCast(u32, x);
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ix = ui & 0x7fffffff;
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// 25+53 bit pi is good enough for medium size
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if (ix < 0x4dc90fdb) { // |x| ~< 2^28*(pi/2), medium size
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// Use a specialized rint() to get fn.
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@"fn" = @floatCast(f64, x) * invpio2 + toint - toint;
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n = @floatToInt(i32, @"fn");
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y.* = x - @"fn" * pio2_1 - @"fn" * pio2_1t;
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// Matters with directed rounding.
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if (y.* < -pio4) {
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n -= 1;
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@"fn" -= 1;
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y.* = x - @"fn" * pio2_1 - @"fn" * pio2_1t;
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} else if (y.* > pio4) {
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n += 1;
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@"fn" += 1;
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y.* = x - @"fn" * pio2_1 - @"fn" * pio2_1t;
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}
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return n;
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}
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if (ix >= 0x7f800000) { // x is inf or NaN
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y.* = x - x;
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return 0;
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}
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// scale x into [2^23, 2^24-1]
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sign = ui >> 31 != 0;
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e0 = (ix >> 23) - (0x7f + 23); // e0 = ilogb(|x|)-23, positive
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ui = ix - (e0 << 23);
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tx[0] = @bitCast(f32, ui);
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n = rem_pio2_large(&tx, &ty, @intCast(i32, e0), 1, 0);
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if (sign) {
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y.* = -ty[0];
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return -n;
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}
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y.* = ty[0];
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return n;
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}
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