Last change
on this file since 387 was 352, checked in by coas-nagasima, 6 years ago |
arm向けASP3版ECNLを追加
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Property svn:eol-style
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File size:
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[352] | 1 | /* origin: FreeBSD /usr/src/lib/msun/src/e_asinf.c */
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| 2 | /*
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| 3 | * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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| 4 | */
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| 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 | #include "libm.h"
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| 16 |
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| 17 | static const double
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| 18 | pio2 = 1.570796326794896558e+00;
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| 19 |
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| 20 | static const float
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| 21 | /* coefficients for R(x^2) */
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| 22 | pS0 = 1.6666586697e-01,
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| 23 | pS1 = -4.2743422091e-02,
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| 24 | pS2 = -8.6563630030e-03,
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| 25 | qS1 = -7.0662963390e-01;
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| 26 |
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| 27 | static float R(float z)
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| 28 | {
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| 29 | float_t p, q;
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| 30 | p = z*(pS0+z*(pS1+z*pS2));
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| 31 | q = 1.0f+z*qS1;
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| 32 | return p/q;
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| 33 | }
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| 34 |
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| 35 | float asinf(float x)
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| 36 | {
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| 37 | double s;
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| 38 | float z;
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| 39 | uint32_t hx,ix;
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| 40 |
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| 41 | GET_FLOAT_WORD(hx, x);
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| 42 | ix = hx & 0x7fffffff;
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| 43 | if (ix >= 0x3f800000) { /* |x| >= 1 */
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| 44 | if (ix == 0x3f800000) /* |x| == 1 */
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| 45 | return x*pio2 + 0x1p-120f; /* asin(+-1) = +-pi/2 with inexact */
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| 46 | return 0/(x-x); /* asin(|x|>1) is NaN */
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| 47 | }
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| 48 | if (ix < 0x3f000000) { /* |x| < 0.5 */
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| 49 | /* if 0x1p-126 <= |x| < 0x1p-12, avoid raising underflow */
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| 50 | if (ix < 0x39800000 && ix >= 0x00800000)
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| 51 | return x;
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| 52 | return x + x*R(x*x);
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| 53 | }
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| 54 | /* 1 > |x| >= 0.5 */
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| 55 | z = (1 - fabsf(x))*0.5f;
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| 56 | s = sqrt(z);
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| 57 | x = pio2 - 2*(s+s*R(z));
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| 58 | if (hx >> 31)
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| 59 | return -x;
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| 60 | return x;
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| 61 | }
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