1251881Speter/* e_atan2f.c -- float version of e_atan2.c. 2251881Speter * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 3251881Speter */ 4251881Speter 5251881Speter/* 6251881Speter * ==================================================== 7251881Speter * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8251881Speter * 9251881Speter * Developed at SunPro, a Sun Microsystems, Inc. business. 10251881Speter * Permission to use, copy, modify, and distribute this 11251881Speter * software is freely granted, provided that this notice 12251881Speter * is preserved. 13251881Speter * ==================================================== 14251881Speter */ 15251881Speter 16251881Speter#include <sys/cdefs.h> 17251881Speter__FBSDID("$FreeBSD$"); 18251881Speter 19251881Speter#include "math.h" 20251881Speter#include "math_private.h" 21251881Speter 22251881Speterstatic volatile float 23251881Spetertiny = 1.0e-30; 24251881Speterstatic const float 25251881Speterzero = 0.0, 26251881Speterpi_o_4 = 7.8539818525e-01, /* 0x3f490fdb */ 27251881Speterpi_o_2 = 1.5707963705e+00, /* 0x3fc90fdb */ 28251881Speterpi = 3.1415927410e+00; /* 0x40490fdb */ 29251881Speterstatic volatile float 30251881Speterpi_lo = -8.7422776573e-08; /* 0xb3bbbd2e */ 31251881Speter 32251881Speterfloat 33251881Speter__ieee754_atan2f(float y, float x) 34251881Speter{ 35251881Speter float z; 36251881Speter int32_t k,m,hx,hy,ix,iy; 37251881Speter 38251881Speter GET_FLOAT_WORD(hx,x); 39251881Speter ix = hx&0x7fffffff; 40251881Speter GET_FLOAT_WORD(hy,y); 41251881Speter iy = hy&0x7fffffff; 42251881Speter if((ix>0x7f800000)|| 43251881Speter (iy>0x7f800000)) /* x or y is NaN */ 44251881Speter return x+y; 45251881Speter if(hx==0x3f800000) return atanf(y); /* x=1.0 */ 46251881Speter m = ((hy>>31)&1)|((hx>>30)&2); /* 2*sign(x)+sign(y) */ 47251881Speter 48251881Speter /* when y = 0 */ 49251881Speter if(iy==0) { 50251881Speter switch(m) { 51251881Speter case 0: 52251881Speter case 1: return y; /* atan(+-0,+anything)=+-0 */ 53251881Speter case 2: return pi+tiny;/* atan(+0,-anything) = pi */ 54251881Speter case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */ 55251881Speter } 56251881Speter } 57251881Speter /* when x = 0 */ 58251881Speter if(ix==0) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny; 59251881Speter 60251881Speter /* when x is INF */ 61251881Speter if(ix==0x7f800000) { 62251881Speter if(iy==0x7f800000) { 63251881Speter switch(m) { 64251881Speter case 0: return pi_o_4+tiny;/* atan(+INF,+INF) */ 65251881Speter case 1: return -pi_o_4-tiny;/* atan(-INF,+INF) */ 66251881Speter case 2: return (float)3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/ 67251881Speter case 3: return (float)-3.0*pi_o_4-tiny;/*atan(-INF,-INF)*/ 68251881Speter } 69251881Speter } else { 70251881Speter switch(m) { 71251881Speter case 0: return zero ; /* atan(+...,+INF) */ 72251881Speter case 1: return -zero ; /* atan(-...,+INF) */ 73251881Speter case 2: return pi+tiny ; /* atan(+...,-INF) */ 74251881Speter case 3: return -pi-tiny ; /* atan(-...,-INF) */ 75251881Speter } 76251881Speter } 77251881Speter } 78251881Speter /* when y is INF */ 79251881Speter if(iy==0x7f800000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny; 80251881Speter 81251881Speter /* compute y/x */ 82251881Speter k = (iy-ix)>>23; 83251881Speter if(k > 26) { /* |y/x| > 2**26 */ 84251881Speter z=pi_o_2+(float)0.5*pi_lo; 85251881Speter m&=1; 86251881Speter } 87251881Speter else if(k<-26&&hx<0) z=0.0; /* 0 > |y|/x > -2**-26 */ 88251881Speter else z=atanf(fabsf(y/x)); /* safe to do y/x */ 89251881Speter switch (m) { 90251881Speter case 0: return z ; /* atan(+,+) */ 91251881Speter case 1: return -z ; /* atan(-,+) */ 92251881Speter case 2: return pi-(z-pi_lo);/* atan(+,-) */ 93251881Speter default: /* case 3 */ 94251881Speter return (z-pi_lo)-pi;/* atan(-,-) */ 95251881Speter } 96251881Speter} 97251881Speter