c6383b7b10
previously 0x1p-1000 and 0x1p1000 was used for raising inexact exception like x+tiny (when x is big) or x+huge (when x is small) the rational is that these float consts are large enough (0x1p-120 + 1 raises inexact even on ld128 which has 113 mant bits) and float consts maybe smaller or easier to load on some platforms (on i386 this reduced the object file size by 4bytes in some cases)
68 lines
1.7 KiB
C
68 lines
1.7 KiB
C
/* origin: FreeBSD /usr/src/lib/msun/src/e_acosl.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 acos.c.
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* Converted to long double by David Schultz <das@FreeBSD.ORG>.
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*/
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#include "libm.h"
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#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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long double acosl(long double x)
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{
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return acos(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 "__invtrigl.h"
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long double acosl(long double x)
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{
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union IEEEl2bits u;
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long double z, w, s, c, df;
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int16_t expsign, expt;
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u.e = x;
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expsign = u.xbits.expsign;
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expt = expsign & 0x7fff;
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/* |x| >= 1 or nan */
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if (expt >= 0x3fff) {
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if (expt == 0x3fff &&
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((u.bits.manh & ~LDBL_NBIT) | u.bits.manl) == 0) {
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if (expsign > 0)
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return 0; /* acos(1) = 0 */
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return 2*pio2_hi + 0x1p-120f; /* acos(-1)= pi */
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}
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return 0/(x-x); /* acos(|x|>1) is NaN */
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}
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/* |x| < 0.5 */
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if (expt < 0x3fff - 1) {
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if (expt < 0x3fff - 65)
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return pio2_hi + 0x1p-120f; /* x < 0x1p-65: acosl(x)=pi/2 */
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return pio2_hi - (x - (pio2_lo - x * __invtrigl_R(x*x)));
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}
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/* x < -0.5 */
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if (expsign < 0) {
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z = (1.0 + x) * 0.5;
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s = sqrtl(z);
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w = __invtrigl_R(z) * s - pio2_lo;
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return 2*(pio2_hi - (s + w));
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}
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/* x > 0.5 */
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z = (1.0 - x) * 0.5;
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s = sqrtl(z);
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u.e = s;
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u.bits.manl = 0;
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df = u.e;
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c = (z - df * df) / (s + df);
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w = __invtrigl_R(z) * s + c;
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return 2*(df + w);
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}
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#endif
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