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