Last change
on this file since 373 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
set to
native
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Property svn:mime-type
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text/x-csrc;charset=UTF-8
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File size:
1.5 KB
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Rev | Line | |
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[352] | 1 | /* origin: FreeBSD /usr/src/lib/msun/src/e_acosf.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 |
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| 16 | #include "libm.h"
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| 17 |
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| 18 | static const float
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| 19 | pio2_hi = 1.5707962513e+00, /* 0x3fc90fda */
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| 20 | pio2_lo = 7.5497894159e-08, /* 0x33a22168 */
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| 21 | pS0 = 1.6666586697e-01,
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| 22 | pS1 = -4.2743422091e-02,
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| 23 | pS2 = -8.6563630030e-03,
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| 24 | qS1 = -7.0662963390e-01;
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| 25 |
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| 26 | static float R(float z)
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| 27 | {
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| 28 | float_t p, q;
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| 29 | p = z*(pS0+z*(pS1+z*pS2));
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| 30 | q = 1.0f+z*qS1;
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| 31 | return p/q;
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| 32 | }
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| 33 |
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| 34 | float acosf(float x)
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| 35 | {
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| 36 | float z,w,s,c,df;
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| 37 | uint32_t hx,ix;
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| 38 |
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| 39 | GET_FLOAT_WORD(hx, x);
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| 40 | ix = hx & 0x7fffffff;
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| 41 | /* |x| >= 1 or nan */
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| 42 | if (ix >= 0x3f800000) {
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| 43 | if (ix == 0x3f800000) {
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| 44 | if (hx >> 31)
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| 45 | return 2*pio2_hi + 0x1p-120f;
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| 46 | return 0;
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| 47 | }
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| 48 | return 0/(x-x);
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| 49 | }
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| 50 | /* |x| < 0.5 */
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| 51 | if (ix < 0x3f000000) {
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| 52 | if (ix <= 0x32800000) /* |x| < 2**-26 */
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| 53 | return pio2_hi + 0x1p-120f;
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| 54 | return pio2_hi - (x - (pio2_lo-x*R(x*x)));
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| 55 | }
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| 56 | /* x < -0.5 */
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| 57 | if (hx >> 31) {
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| 58 | z = (1+x)*0.5f;
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| 59 | s = sqrtf(z);
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| 60 | w = R(z)*s-pio2_lo;
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| 61 | return 2*(pio2_hi - (s+w));
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| 62 | }
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| 63 | /* x > 0.5 */
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| 64 | z = (1-x)*0.5f;
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| 65 | s = sqrtf(z);
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| 66 | GET_FLOAT_WORD(hx,s);
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| 67 | SET_FLOAT_WORD(df,hx&0xfffff000);
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| 68 | c = (z-df*df)/(s+df);
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| 69 | w = R(z)*s+c;
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| 70 | return 2*(df+w);
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| 71 | }
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