1/* e_atan2f.c -- float version of e_atan2.c.
2 */
3
4/*
5 * ====================================================
6 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
7 *
8 * Developed at SunPro, a Sun Microsystems, Inc. business.
9 * Permission to use, copy, modify, and distribute this
10 * software is freely granted, provided that this notice
11 * is preserved.
12 * ====================================================
13 */
14
15#include <math.h>
16#include <math_private.h>
17#include <libm-alias-finite.h>
18
19static const float
20tiny = 1.0e-30,
21zero = 0.0,
22pi_o_4 = 7.8539818525e-01, /* 0x3f490fdb */
23pi_o_2 = 1.5707963705e+00, /* 0x3fc90fdb */
24pi = 3.1415927410e+00, /* 0x40490fdb */
25pi_lo = -8.7422776573e-08; /* 0xb3bbbd2e */
26
27float
28__ieee754_atan2f (float y, float x)
29{
30 float z;
31 int32_t k,m,hx,hy,ix,iy;
32
33 GET_FLOAT_WORD(hx,x);
34 ix = hx&0x7fffffff;
35 GET_FLOAT_WORD(hy,y);
36 iy = hy&0x7fffffff;
37 if((ix>0x7f800000)||
38 (iy>0x7f800000)) /* x or y is NaN */
39 return x+y;
40 if(hx==0x3f800000) return __atanf(y); /* x=1.0 */
41 m = ((hy>>31)&1)|((hx>>30)&2); /* 2*sign(x)+sign(y) */
42
43 /* when y = 0 */
44 if(iy==0) {
45 switch(m) {
46 case 0:
47 case 1: return y; /* atan(+-0,+anything)=+-0 */
48 case 2: return pi+tiny;/* atan(+0,-anything) = pi */
49 case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */
50 }
51 }
52 /* when x = 0 */
53 if(ix==0) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;
54
55 /* when x is INF */
56 if(ix==0x7f800000) {
57 if(iy==0x7f800000) {
58 switch(m) {
59 case 0: return pi_o_4+tiny;/* atan(+INF,+INF) */
60 case 1: return -pi_o_4-tiny;/* atan(-INF,+INF) */
61 case 2: return (float)3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/
62 case 3: return (float)-3.0*pi_o_4-tiny;/*atan(-INF,-INF)*/
63 }
64 } else {
65 switch(m) {
66 case 0: return zero ; /* atan(+...,+INF) */
67 case 1: return -zero ; /* atan(-...,+INF) */
68 case 2: return pi+tiny ; /* atan(+...,-INF) */
69 case 3: return -pi-tiny ; /* atan(-...,-INF) */
70 }
71 }
72 }
73 /* when y is INF */
74 if(iy==0x7f800000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;
75
76 /* compute y/x */
77 k = (iy-ix)>>23;
78 if(k > 60) z=pi_o_2+(float)0.5*pi_lo; /* |y/x| > 2**60 */
79 else if(hx<0&&k<-60) z=0.0; /* |y|/x < -2**60 */
80 else z=__atanf(fabsf(y/x)); /* safe to do y/x */
81 switch (m) {
82 case 0: return z ; /* atan(+,+) */
83 case 1: {
84 uint32_t zh;
85 GET_FLOAT_WORD(zh,z);
86 SET_FLOAT_WORD(z,zh ^ 0x80000000);
87 }
88 return z ; /* atan(-,+) */
89 case 2: return pi-(z-pi_lo);/* atan(+,-) */
90 default: /* case 3 */
91 return (z-pi_lo)-pi;/* atan(-,-) */
92 }
93}
94libm_alias_finite (__ieee754_atan2f, __atan2f)
95