mirror of
https://github.com/jart/cosmopolitan.git
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550b52abf6
- Introduce epoll_pwait() - Rewrite -ftrapv and ffs() libraries in C code - Use more FreeBSD code in math function library - Get significantly more tests passing on qemu-aarch64 - Fix many Musl long double functions that were broken on AARCH64
154 lines
6.8 KiB
C
154 lines
6.8 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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│ FreeBSD lib/msun/src/e_atan2.c │
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│ │
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│ Copyright (c) 1992-2023 The FreeBSD Project. │
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│ │
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│ Redistribution and use in source and binary forms, with or without │
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│ modification, are permitted provided that the following conditions │
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│ are met: │
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│ 1. Redistributions of source code must retain the above copyright │
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│ notice, this list of conditions and the following disclaimer. │
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│ 2. Redistributions in binary form must reproduce the above copyright │
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│ notice, this list of conditions and the following disclaimer in the │
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│ documentation and/or other materials provided with the distribution. │
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│ │
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│ THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND │
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│ ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE │
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│ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE │
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│ ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE │
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│ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL │
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│ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS │
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│ OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) │
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│ HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT │
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│ LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY │
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│ OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF │
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│ SUCH DAMAGE. │
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│ │
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│ Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. │
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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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#include "libc/math.h"
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#include "libc/tinymath/freebsd.internal.h"
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asm(".ident\t\"\\n\\n\
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FreeBSD libm (BSD-2 License)\\n\
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Copyright (c) 2005-2011, Bruce D. Evans, Steven G. Kargl, David Schultz.\"");
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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(".include \"libc/disclaimer.inc\"");
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// clang-format off
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/* atan2(y,x)
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* Method :
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* 1. Reduce y to positive by atan2(y,x)=-atan2(-y,x).
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* 2. Reduce x to positive by (if x and y are unexceptional):
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* ARG (x+iy) = arctan(y/x) ... if x > 0,
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* ARG (x+iy) = pi - arctan[y/(-x)] ... if x < 0,
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*
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* Special cases:
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*
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* ATAN2((anything), NaN ) is NaN;
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* ATAN2(NAN , (anything) ) is NaN;
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* ATAN2(+-0, +(anything but NaN)) is +-0 ;
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* ATAN2(+-0, -(anything but NaN)) is +-pi ;
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* ATAN2(+-(anything but 0 and NaN), 0) is +-pi/2;
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* ATAN2(+-(anything but INF and NaN), +INF) is +-0 ;
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* ATAN2(+-(anything but INF and NaN), -INF) is +-pi;
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* ATAN2(+-INF,+INF ) is +-pi/4 ;
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* ATAN2(+-INF,-INF ) is +-3pi/4;
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* ATAN2(+-INF, (anything but,0,NaN, and INF)) is +-pi/2;
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*
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* Constants:
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* The hexadecimal values are the intended ones for the following
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* constants. The decimal values may be used, provided that the
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* compiler will convert from decimal to binary accurately enough
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* to produce the hexadecimal values shown.
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*/
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static volatile double
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tiny = 1.0e-300;
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static const double
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zero = 0.0,
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pi_o_4 = 7.8539816339744827900E-01, /* 0x3FE921FB, 0x54442D18 */
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pi_o_2 = 1.5707963267948965580E+00, /* 0x3FF921FB, 0x54442D18 */
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pi = 3.1415926535897931160E+00; /* 0x400921FB, 0x54442D18 */
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static volatile double
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pi_lo = 1.2246467991473531772E-16; /* 0x3CA1A626, 0x33145C07 */
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/**
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* Returns arc tangent of 𝑦/𝑥.
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*/
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double
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atan2(double y, double x)
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{
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double z;
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int32_t k,m,hx,hy,ix,iy;
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uint32_t lx,ly;
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EXTRACT_WORDS(hx,lx,x);
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ix = hx&0x7fffffff;
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EXTRACT_WORDS(hy,ly,y);
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iy = hy&0x7fffffff;
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if(((ix|((lx|-lx)>>31))>0x7ff00000)||
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((iy|((ly|-ly)>>31))>0x7ff00000)) /* x or y is NaN */
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return nan_mix(x, y);
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if(hx==0x3ff00000&&lx==0) return atan(y); /* x=1.0 */
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m = ((hy>>31)&1)|((hx>>30)&2); /* 2*sign(x)+sign(y) */
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/* when y = 0 */
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if((iy|ly)==0) {
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switch(m) {
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case 0:
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case 1: return y; /* atan(+-0,+anything)=+-0 */
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case 2: return pi+tiny;/* atan(+0,-anything) = pi */
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case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */
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}
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}
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/* when x = 0 */
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if((ix|lx)==0) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;
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/* when x is INF */
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if(ix==0x7ff00000) {
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if(iy==0x7ff00000) {
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switch(m) {
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case 0: return pi_o_4+tiny;/* atan(+INF,+INF) */
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case 1: return -pi_o_4-tiny;/* atan(-INF,+INF) */
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case 2: return 3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/
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case 3: return -3.0*pi_o_4-tiny;/*atan(-INF,-INF)*/
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}
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} else {
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switch(m) {
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case 0: return zero ; /* atan(+...,+INF) */
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case 1: return -zero ; /* atan(-...,+INF) */
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case 2: return pi+tiny ; /* atan(+...,-INF) */
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case 3: return -pi-tiny ; /* atan(-...,-INF) */
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}
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}
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}
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/* when y is INF */
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if(iy==0x7ff00000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;
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/* compute y/x */
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k = (iy-ix)>>20;
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if(k > 60) { /* |y/x| > 2**60 */
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z=pi_o_2+0.5*pi_lo;
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m&=1;
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}
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else if(hx<0&&k<-60) z=0.0; /* 0 > |y|/x > -2**-60 */
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else z=atan(fabs(y/x)); /* safe to do y/x */
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switch (m) {
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case 0: return z ; /* atan(+,+) */
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case 1: return -z ; /* atan(-,+) */
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case 2: return pi-(z-pi_lo);/* atan(+,-) */
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default: /* case 3 */
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return (z-pi_lo)-pi;/* atan(-,-) */
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}
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}
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