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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 3362 | Serge | 1 | /* ef_asin.c -- float version of e_asin.c. |
| 2 | * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
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| 3 | */ |
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| 4 | |||
| 5 | /* |
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| 6 | * ==================================================== |
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| 7 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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| 8 | * |
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| 9 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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| 10 | * Permission to use, copy, modify, and distribute this |
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| 11 | * software is freely granted, provided that this notice |
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| 12 | * is preserved. |
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| 13 | * ==================================================== |
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| 14 | */ |
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| 15 | |||
| 16 | #include "fdlibm.h" |
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| 17 | |||
| 18 | #ifdef __STDC__ |
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| 19 | static const float |
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| 20 | #else |
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| 21 | static float |
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| 22 | #endif |
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| 23 | one = 1.0000000000e+00, /* 0x3F800000 */ |
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| 24 | huge = 1.000e+30, |
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| 25 | pio2_hi = 1.57079637050628662109375f, |
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| 26 | pio2_lo = -4.37113900018624283e-8f, |
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| 27 | pio4_hi = 0.785398185253143310546875f, |
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| 28 | /* coefficient for R(x^2) */ |
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| 29 | pS0 = 1.6666667163e-01, /* 0x3e2aaaab */ |
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| 30 | pS1 = -3.2556581497e-01, /* 0xbea6b090 */ |
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| 31 | pS2 = 2.0121252537e-01, /* 0x3e4e0aa8 */ |
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| 32 | pS3 = -4.0055535734e-02, /* 0xbd241146 */ |
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| 33 | pS4 = 7.9153501429e-04, /* 0x3a4f7f04 */ |
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| 34 | pS5 = 3.4793309169e-05, /* 0x3811ef08 */ |
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| 35 | qS1 = -2.4033949375e+00, /* 0xc019d139 */ |
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| 36 | qS2 = 2.0209457874e+00, /* 0x4001572d */ |
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| 37 | qS3 = -6.8828397989e-01, /* 0xbf303361 */ |
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| 38 | qS4 = 7.7038154006e-02; /* 0x3d9dc62e */ |
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| 39 | |||
| 40 | #ifdef __STDC__ |
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| 41 | float __ieee754_asinf(float x) |
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| 42 | #else |
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| 43 | float __ieee754_asinf(x) |
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| 44 | float x; |
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| 45 | #endif |
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| 46 | { |
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| 47 | float t,w,p,q,c,r,s; |
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| 48 | __int32_t hx,ix; |
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| 49 | GET_FLOAT_WORD(hx,x); |
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| 50 | ix = hx&0x7fffffff; |
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| 51 | if(ix==0x3f800000) { |
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| 52 | /* asin(1)=+-pi/2 with inexact */ |
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| 53 | return x*pio2_hi+x*pio2_lo; |
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| 54 | } else if(ix> 0x3f800000) { /* |x|>= 1 */ |
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| 55 | return (x-x)/(x-x); /* asin(|x|>1) is NaN */ |
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| 56 | } else if (ix<0x3f000000) { /* |x|<0.5 */ |
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| 57 | if(ix<0x32000000) { /* if |x| < 2**-27 */ |
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| 58 | if(huge+x>one) return x;/* return x with inexact if x!=0*/ |
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| 59 | } else { |
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| 60 | t = x*x; |
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| 61 | p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5))))); |
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| 62 | q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4))); |
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| 63 | w = p/q; |
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| 64 | return x+x*w; |
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| 65 | } |
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| 66 | } |
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| 67 | /* 1> |x|>= 0.5 */ |
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| 68 | w = one-fabsf(x); |
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| 69 | t = w*(float)0.5; |
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| 70 | p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5))))); |
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| 71 | q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4))); |
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| 72 | s = __ieee754_sqrtf(t); |
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| 73 | if(ix>=0x3F79999A) { /* if |x| > 0.975 */ |
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| 74 | w = p/q; |
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| 75 | t = pio2_hi-((float)2.0*(s+s*w)-pio2_lo); |
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| 76 | } else { |
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| 77 | __int32_t iw; |
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| 78 | w = s; |
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| 79 | GET_FLOAT_WORD(iw,w); |
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| 80 | SET_FLOAT_WORD(w,iw&0xfffff000); |
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| 81 | c = (t-w*w)/(s+w); |
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| 82 | r = p/q; |
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| 83 | p = (float)2.0*s*r-(pio2_lo-(float)2.0*c); |
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| 84 | q = pio4_hi-(float)2.0*w; |
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| 85 | t = pio4_hi-(p-q); |
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| 86 | } |
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| 87 | if(hx>0) return t; else return -t; |
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| 88 | } |