mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-01-31 19:43:32 +00:00
122 lines
5.1 KiB
C
122 lines
5.1 KiB
C
/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8 -*-│
|
||
│vi: set et ft=c ts=8 tw=8 fenc=utf-8 :vi│
|
||
╚──────────────────────────────────────────────────────────────────────────────╝
|
||
│ │
|
||
│ Musl Libc │
|
||
│ Copyright © 2005-2014 Rich Felker, et al. │
|
||
│ │
|
||
│ Permission is hereby granted, free of charge, to any person obtaining │
|
||
│ a copy of this software and associated documentation files (the │
|
||
│ "Software"), to deal in the Software without restriction, including │
|
||
│ without limitation the rights to use, copy, modify, merge, publish, │
|
||
│ distribute, sublicense, and/or sell copies of the Software, and to │
|
||
│ permit persons to whom the Software is furnished to do so, subject to │
|
||
│ the following conditions: │
|
||
│ │
|
||
│ The above copyright notice and this permission notice shall be │
|
||
│ included in all copies or substantial portions of the Software. │
|
||
│ │
|
||
│ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, │
|
||
│ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF │
|
||
│ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. │
|
||
│ IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY │
|
||
│ CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, │
|
||
│ TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE │
|
||
│ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. │
|
||
│ │
|
||
╚─────────────────────────────────────────────────────────────────────────────*/
|
||
#include "libc/math.h"
|
||
#include "libc/tinymath/feval.internal.h"
|
||
#include "libc/tinymath/kernel.internal.h"
|
||
|
||
asm(".ident\t\"\\n\\n\
|
||
fdlibm (fdlibm license)\\n\
|
||
Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.\"");
|
||
asm(".ident\t\"\\n\\n\
|
||
Musl libc (MIT License)\\n\
|
||
Copyright 2005-2014 Rich Felker, et. al.\"");
|
||
asm(".include \"libc/disclaimer.inc\"");
|
||
/* clang-format off */
|
||
|
||
/* origin: FreeBSD /usr/src/lib/msun/src/s_cos.c */
|
||
/*
|
||
* ====================================================
|
||
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
||
*
|
||
* Developed at SunPro, a Sun Microsystems, Inc. business.
|
||
* Permission to use, copy, modify, and distribute this
|
||
* software is freely granted, provided that this notice
|
||
* is preserved.
|
||
* ====================================================
|
||
*/
|
||
/* cos(x)
|
||
* Return cosine function of x.
|
||
*
|
||
* kernel function:
|
||
* __sin ... sine function on [-pi/4,pi/4]
|
||
* __cos ... cosine function on [-pi/4,pi/4]
|
||
* __rem_pio2 ... argument reduction routine
|
||
*
|
||
* Method.
|
||
* Let S,C and T denote the sin, cos and tan respectively on
|
||
* [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
|
||
* in [-pi/4 , +pi/4], and let n = k mod 4.
|
||
* We have
|
||
*
|
||
* n sin(x) cos(x) tan(x)
|
||
* ----------------------------------------------------------
|
||
* 0 S C T
|
||
* 1 C -S -1/T
|
||
* 2 -S -C T
|
||
* 3 -C S -1/T
|
||
* ----------------------------------------------------------
|
||
*
|
||
* Special cases:
|
||
* Let trig be any of sin, cos, or tan.
|
||
* trig(+-INF) is NaN, with signals;
|
||
* trig(NaN) is that NaN;
|
||
*
|
||
* Accuracy:
|
||
* TRIG(x) returns trig(x) nearly rounded
|
||
*/
|
||
|
||
#define asuint64(f) ((union{double _f; uint64_t _i;}){f})._i
|
||
#define gethighw(hi,d) (hi) = asuint64(d) >> 32
|
||
|
||
/**
|
||
* Returns cosine of 𝑥.
|
||
* @note should take ~5ns
|
||
*/
|
||
double cos(double x)
|
||
{
|
||
double y[2];
|
||
uint32_t ix;
|
||
unsigned n;
|
||
|
||
gethighw(ix, x);
|
||
ix &= 0x7fffffff;
|
||
|
||
/* |x| ~< pi/4 */
|
||
if (ix <= 0x3fe921fb) {
|
||
if (ix < 0x3e46a09e) { /* |x| < 2**-27 * sqrt(2) */
|
||
/* raise inexact if x!=0 */
|
||
feval(x + 0x1p120f);
|
||
return 1.0;
|
||
}
|
||
return __cos(x, 0);
|
||
}
|
||
|
||
/* cos(Inf or NaN) is NaN */
|
||
if (ix >= 0x7ff00000)
|
||
return x-x;
|
||
|
||
/* argument reduction */
|
||
n = __rem_pio2(x, y);
|
||
switch (n&3) {
|
||
case 0: return __cos(y[0], y[1]);
|
||
case 1: return -__sin(y[0], y[1], 1);
|
||
case 2: return -__cos(y[0], y[1]);
|
||
default:
|
||
return __sin(y[0], y[1], 1);
|
||
}
|
||
}
|