72 lines
1.8 KiB
C
72 lines
1.8 KiB
C
/* origin: FreeBSD /usr/src/lib/msun/src/e_asinl.c */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunSoft, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/*
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* See comments in asin.c.
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* Converted to long double by David Schultz <das@FreeBSD.ORG>.
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*/
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#include "libc/math/libm.h"
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#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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long double asinl(long double x)
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{
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return asin(x);
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}
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#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
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#include "libc/math/__invtrigl.h"
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#if LDBL_MANT_DIG == 64
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#define CLOSETO1(u) (u.i.m>>56 >= 0xf7)
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#define CLEARBOTTOM(u) (u.i.m &= -1ULL << 32)
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#elif LDBL_MANT_DIG == 113
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#define CLOSETO1(u) (u.i.top >= 0xee00)
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#define CLEARBOTTOM(u) (u.i.lo = 0)
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#endif
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long double asinl(long double x)
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{
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union ldshape u = {x};
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long double z, r, s;
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uint16_t e = u.i.se & 0x7fff;
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int sign = u.i.se >> 15;
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if (e >= 0x3fff) { /* |x| >= 1 or nan */
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/* asin(+-1)=+-pi/2 with inexact */
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if (x == 1 || x == -1)
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return x*pio2_hi + 0x1p-120f;
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return 0/(x-x);
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}
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if (e < 0x3fff - 1) { /* |x| < 0.5 */
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if (e < 0x3fff - (LDBL_MANT_DIG+1)/2) {
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/* return x with inexact if x!=0 */
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FORCE_EVAL(x + 0x1p120f);
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return x;
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}
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return x + x*__invtrigl_R(x*x);
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}
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/* 1 > |x| >= 0.5 */
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z = (1.0 - fabsl(x))*0.5;
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s = sqrtl(z);
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r = __invtrigl_R(z);
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if (CLOSETO1(u)) {
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x = pio2_hi - (2*(s+s*r)-pio2_lo);
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} else {
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long double f, c;
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u.f = s;
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CLEARBOTTOM(u);
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f = u.f;
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c = (z - f*f)/(s + f);
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x = 0.5*pio2_hi-(2*s*r - (pio2_lo-2*c) - (0.5*pio2_hi-2*f));
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}
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return sign ? -x : x;
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}
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#endif
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