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 #ifndef lint 17 static char rcsid[] = "$FreeBSD$"; 18 #endif 19 20 #include "math.h" 21 #include "math_private.h" 22 23 #ifdef __STDC__ 24 static const float 25 #else 26 static float 27 #endif 28 tiny = 1.0e-30, 29 zero = 0.0, 30 pi_o_4 = 7.8539818525e-01, /* 0x3f490fdb */ 31 pi_o_2 = 1.5707963705e+00, /* 0x3fc90fdb */ 32 pi = 3.1415925026e+00, /* 0x40490fda */ 33 pi_lo = 1.5099578832e-07; /* 0x34222168 */ 34 35 #ifdef __STDC__ 36 float __ieee754_atan2f(float y, float x) 37 #else 38 float __ieee754_atan2f(y,x) 39 float y,x; 40 #endif 41 { 42 float z; 43 int32_t k,m,hx,hy,ix,iy; 44 45 GET_FLOAT_WORD(hx,x); 46 ix = hx&0x7fffffff; 47 GET_FLOAT_WORD(hy,y); 48 iy = hy&0x7fffffff; 49 if((ix>0x7f800000)|| 50 (iy>0x7f800000)) /* x or y is NaN */ 51 return x+y; 52 if(hx==0x3f800000) return atanf(y); /* x=1.0 */ 53 m = ((hy>>31)&1)|((hx>>30)&2); /* 2*sign(x)+sign(y) */ 54 55 /* when y = 0 */ 56 if(iy==0) { 57 switch(m) { 58 case 0: 59 case 1: return y; /* atan(+-0,+anything)=+-0 */ 60 case 2: return pi+tiny;/* atan(+0,-anything) = pi */ 61 case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */ 62 } 63 } 64 /* when x = 0 */ 65 if(ix==0) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny; 66 67 /* when x is INF */ 68 if(ix==0x7f800000) { 69 if(iy==0x7f800000) { 70 switch(m) { 71 case 0: return pi_o_4+tiny;/* atan(+INF,+INF) */ 72 case 1: return -pi_o_4-tiny;/* atan(-INF,+INF) */ 73 case 2: return (float)3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/ 74 case 3: return (float)-3.0*pi_o_4-tiny;/*atan(-INF,-INF)*/ 75 } 76 } else { 77 switch(m) { 78 case 0: return zero ; /* atan(+...,+INF) */ 79 case 1: return -zero ; /* atan(-...,+INF) */ 80 case 2: return pi+tiny ; /* atan(+...,-INF) */ 81 case 3: return -pi-tiny ; /* atan(-...,-INF) */ 82 } 83 } 84 } 85 /* when y is INF */ 86 if(iy==0x7f800000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny; 87 88 /* compute y/x */ 89 k = (iy-ix)>>23; 90 if(k > 60) z=pi_o_2+(float)0.5*pi_lo; /* |y/x| > 2**60 */ 91 else if(hx<0&&k<-60) z=0.0; /* |y|/x < -2**60 */ 92 else z=atanf(fabsf(y/x)); /* safe to do y/x */ 93 switch (m) { 94 case 0: return z ; /* atan(+,+) */ 95 case 1: { 96 u_int32_t zh; 97 GET_FLOAT_WORD(zh,z); 98 SET_FLOAT_WORD(z,zh ^ 0x80000000); 99 } 100 return z ; /* atan(-,+) */ 101 case 2: return pi-(z-pi_lo);/* atan(+,-) */ 102 default: /* case 3 */ 103 return (z-pi_lo)-pi;/* atan(-,-) */ 104 } 105 } 106