1 /* e_atan2f.c -- float version of e_atan2.c. 2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 3 */ 4 5 /* 6 * ==================================================== 7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8 * 9 * Developed at SunPro, a Sun Microsystems, Inc. business. 10 * Permission to use, copy, modify, and distribute this 11 * software is freely granted, provided that this notice 12 * is preserved. 13 * ==================================================== 14 */ 15 16 #include "cdefs-compat.h" 17 //__FBSDID("$FreeBSD: src/lib/msun/src/e_atan2f.c,v 1.12 2008/08/03 17:39:54 das Exp $"); 18 19 #include <openlibm_math.h> 20 21 #include "math_private.h" 22 23 static volatile float 24 tiny = 1.0e-30; 25 static const float 26 zero = 0.0, 27 pi_o_4 = 7.8539818525e-01, /* 0x3f490fdb */ 28 pi_o_2 = 1.5707963705e+00, /* 0x3fc90fdb */ 29 pi = 3.1415927410e+00; /* 0x40490fdb */ 30 static volatile float 31 pi_lo = -8.7422776573e-08; /* 0xb3bbbd2e */ 32 33 OLM_DLLEXPORT float 34 __ieee754_atan2f(float y, float x) 35 { 36 float z; 37 int32_t k,m,hx,hy,ix,iy; 38 39 GET_FLOAT_WORD(hx,x); 40 ix = hx&0x7fffffff; 41 GET_FLOAT_WORD(hy,y); 42 iy = hy&0x7fffffff; 43 if((ix>0x7f800000)|| 44 (iy>0x7f800000)) /* x or y is NaN */ 45 return x+y; 46 if(hx==0x3f800000) return atanf(y); /* x=1.0 */ 47 m = ((hy>>31)&1)|((hx>>30)&2); /* 2*sign(x)+sign(y) */ 48 49 /* when y = 0 */ 50 if(iy==0) { 51 switch(m) { 52 case 0: 53 case 1: return y; /* atan(+-0,+anything)=+-0 */ 54 case 2: return pi+tiny;/* atan(+0,-anything) = pi */ 55 case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */ 56 } 57 } 58 /* when x = 0 */ 59 if(ix==0) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny; 60 61 /* when x is INF */ 62 if(ix==0x7f800000) { 63 if(iy==0x7f800000) { 64 switch(m) { 65 case 0: return pi_o_4+tiny;/* atan(+INF,+INF) */ 66 case 1: return -pi_o_4-tiny;/* atan(-INF,+INF) */ 67 case 2: return (float)3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/ 68 case 3: return (float)-3.0*pi_o_4-tiny;/*atan(-INF,-INF)*/ 69 } 70 } else { 71 switch(m) { 72 case 0: return zero ; /* atan(+...,+INF) */ 73 case 1: return -zero ; /* atan(-...,+INF) */ 74 case 2: return pi+tiny ; /* atan(+...,-INF) */ 75 case 3: return -pi-tiny ; /* atan(-...,-INF) */ 76 } 77 } 78 } 79 /* when y is INF */ 80 if(iy==0x7f800000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny; 81 82 /* compute y/x */ 83 k = (iy-ix)>>23; 84 if(k > 26) { /* |y/x| > 2**26 */ 85 z=pi_o_2+(float)0.5*pi_lo; 86 m&=1; 87 } 88 else if(k<-26&&hx<0) z=0.0; /* 0 > |y|/x > -2**-26 */ 89 else z=atanf(fabsf(y/x)); /* safe to do y/x */ 90 switch (m) { 91 case 0: return z ; /* atan(+,+) */ 92 case 1: return -z ; /* atan(-,+) */ 93 case 2: return pi-(z-pi_lo);/* atan(+,-) */ 94 default: /* case 3 */ 95 return (z-pi_lo)-pi;/* atan(-,-) */ 96 } 97 } 98