mirror of
https://github.com/jart/cosmopolitan.git
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124 lines
5.1 KiB
C
124 lines
5.1 KiB
C
/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8 -*-│
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│vi: set et ft=c ts=8 tw=8 fenc=utf-8 :vi│
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╚──────────────────────────────────────────────────────────────────────────────╝
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│ │
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│ Musl Libc │
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│ Copyright © 2005-2014 Rich Felker, et al. │
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│ │
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│ Permission is hereby granted, free of charge, to any person obtaining │
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│ a copy of this software and associated documentation files (the │
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│ "Software"), to deal in the Software without restriction, including │
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│ without limitation the rights to use, copy, modify, merge, publish, │
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│ distribute, sublicense, and/or sell copies of the Software, and to │
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│ permit persons to whom the Software is furnished to do so, subject to │
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│ the following conditions: │
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│ │
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│ The above copyright notice and this permission notice shall be │
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│ included in all copies or substantial portions of the Software. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, │
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│ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF │
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│ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. │
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│ IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY │
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│ CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, │
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│ TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE │
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│ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. │
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│ │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/intrin/likely.h"
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#include "libc/math.h"
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#include "libc/tinymath/kernel.internal.h"
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asm(".ident\t\"\\n\\n\
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fdlibm (fdlibm license)\\n\
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Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.\"");
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asm(".ident\t\"\\n\\n\
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Musl libc (MIT License)\\n\
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Copyright 2005-2014 Rich Felker, et. al.\"");
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asm(".include \"libc/disclaimer.inc\"");
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/* clang-format off */
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/* origin: FreeBSD /usr/src/lib/msun/src/e_rem_pio2f.c */
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/*
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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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* Debugged and optimized by Bruce D. Evans.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/* __rem_pio2f(x,y)
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*
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* return 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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*/
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#if FLT_EVAL_METHOD==0 || FLT_EVAL_METHOD==1
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#define EPS DBL_EPSILON
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#elif FLT_EVAL_METHOD==2
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#define EPS LDBL_EPSILON
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#endif
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/*
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* invpio2: 53 bits of 2/pi
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* pio2_1: first 25 bits of pi/2
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* pio2_1t: pi/2 - pio2_1
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*/
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static const double
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toint = 1.5/EPS,
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pio4 = 0x1.921fb6p-1,
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invpio2 = 6.36619772367581382433e-01, /* 0x3FE45F30, 0x6DC9C883 */
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pio2_1 = 1.57079631090164184570e+00, /* 0x3FF921FB, 0x50000000 */
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pio2_1t = 1.58932547735281966916e-08; /* 0x3E5110b4, 0x611A6263 */
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int __rem_pio2f(float x, double *y)
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{
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union {float f; uint32_t i;} u = {x};
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double tx[1],ty[1];
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double_t fn;
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uint32_t ix;
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int n, sign, e0;
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ix = u.i & 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 = (double_t)x*invpio2 + toint - toint;
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n = (int32_t)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 (UNLIKELY(*y < -pio4)) {
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n--;
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fn--;
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*y = x - fn*pio2_1 - fn*pio2_1t;
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} else if (UNLIKELY(*y > pio4)) {
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n++;
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fn++;
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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 = u.i>>31;
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e0 = (ix>>23) - (0x7f+23); /* e0 = ilogb(|x|)-23, positive */
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u.i = ix - (e0<<23);
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tx[0] = u.f;
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n = __rem_pio2_large(tx,ty,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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