| /* origin: FreeBSD /usr/src/lib/msun/src/e_acosl.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 acos.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 acosl(long double x) |
| { |
| return acos(x); |
| } |
| #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384 |
| #include "__invtrigl.h" |
| #if LDBL_MANT_DIG == 64 |
| #define CLEARBOTTOM(u) (u.i.m &= -1ULL << 32) |
| #elif LDBL_MANT_DIG == 113 |
| #define CLEARBOTTOM(u) (u.i.lo = 0) |
| #endif |
| |
| long double acosl(long double x) |
| { |
| union ldshape u = {x}; |
| long double z, s, c, f; |
| uint16_t e = u.i.se & 0x7fff; |
| |
| /* |x| >= 1 or nan */ |
| if (e >= 0x3fff) { |
| if (x == 1) |
| return 0; |
| if (x == -1) |
| return 2*pio2_hi + 0x1p-120f; |
| return 0/(x-x); |
| } |
| /* |x| < 0.5 */ |
| if (e < 0x3fff - 1) { |
| if (e < 0x3fff - LDBL_MANT_DIG - 1) |
| return pio2_hi + 0x1p-120f; |
| return pio2_hi - (__invtrigl_R(x*x)*x - pio2_lo + x); |
| } |
| /* x < -0.5 */ |
| if (u.i.se >> 15) { |
| z = (1 + x)*0.5; |
| s = sqrtl(z); |
| return 2*(pio2_hi - (__invtrigl_R(z)*s - pio2_lo + s)); |
| } |
| /* x > 0.5 */ |
| z = (1 - x)*0.5; |
| s = sqrtl(z); |
| u.f = s; |
| CLEARBOTTOM(u); |
| f = u.f; |
| c = (z - f*f)/(s + f); |
| return 2*(__invtrigl_R(z)*s + c + f); |
| } |
| #endif |
