1 /* e_asinf.c -- float version of e_asin.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 <sys/cdefs.h> 17 #if defined(LIBM_SCCS) && !defined(lint) 18 __RCSID("$NetBSD: e_asinf.c,v 1.7 1999/07/02 15:37:38 simonb Exp $"); 19 #endif 20 21 #include "math.h" 22 #include "math_private.h" 23 24 #ifdef __STDC__ 25 static const float 26 #else 27 static float 28 #endif 29 one = 1.0000000000e+00, /* 0x3F800000 */ 30 huge = 1.000e+30, 31 pio2_hi = 1.5707962513e+00, /* 0x3fc90fda */ 32 pio2_lo = 7.5497894159e-08, /* 0x33a22168 */ 33 pio4_hi = 7.8539818525e-01, /* 0x3f490fdb */ 34 /* coefficient for R(x^2) */ 35 pS0 = 1.6666667163e-01, /* 0x3e2aaaab */ 36 pS1 = -3.2556581497e-01, /* 0xbea6b090 */ 37 pS2 = 2.0121252537e-01, /* 0x3e4e0aa8 */ 38 pS3 = -4.0055535734e-02, /* 0xbd241146 */ 39 pS4 = 7.9153501429e-04, /* 0x3a4f7f04 */ 40 pS5 = 3.4793309169e-05, /* 0x3811ef08 */ 41 qS1 = -2.4033949375e+00, /* 0xc019d139 */ 42 qS2 = 2.0209457874e+00, /* 0x4001572d */ 43 qS3 = -6.8828397989e-01, /* 0xbf303361 */ 44 qS4 = 7.7038154006e-02; /* 0x3d9dc62e */ 45 46 #ifdef __STDC__ 47 float __ieee754_asinf(float x) 48 #else 49 float __ieee754_asinf(x) 50 float x; 51 #endif 52 { 53 float t,w,p,q,c,r,s; 54 int32_t hx,ix; 55 56 t = 0; 57 GET_FLOAT_WORD(hx,x); 58 ix = hx&0x7fffffff; 59 if(ix==0x3f800000) { 60 /* asin(1)=+-pi/2 with inexact */ 61 return x*pio2_hi+x*pio2_lo; 62 } else if(ix> 0x3f800000) { /* |x|>= 1 */ 63 return (x-x)/(x-x); /* asin(|x|>1) is NaN */ 64 } else if (ix<0x3f000000) { /* |x|<0.5 */ 65 if(ix<0x32000000) { /* if |x| < 2**-27 */ 66 if(huge+x>one) return x;/* return x with inexact if x!=0*/ 67 } else 68 t = x*x; 69 p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5))))); 70 q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4))); 71 w = p/q; 72 return x+x*w; 73 } 74 /* 1> |x|>= 0.5 */ 75 w = one-fabsf(x); 76 t = w*(float)0.5; 77 p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5))))); 78 q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4))); 79 s = __ieee754_sqrtf(t); 80 if(ix>=0x3F79999A) { /* if |x| > 0.975 */ 81 w = p/q; 82 t = pio2_hi-((float)2.0*(s+s*w)-pio2_lo); 83 } else { 84 int32_t iw; 85 w = s; 86 GET_FLOAT_WORD(iw,w); 87 SET_FLOAT_WORD(w,iw&0xfffff000); 88 c = (t-w*w)/(s+w); 89 r = p/q; 90 p = (float)2.0*s*r-(pio2_lo-(float)2.0*c); 91 q = pio4_hi-(float)2.0*w; 92 t = pio4_hi-(p-q); 93 } 94 if(hx>0) return t; else return -t; 95 } 96