projects / thirdparty / glibc.git / blame
| Commit | Line | Data |
|---|---|---|
| abfbdde1 UD |
1 | /* s_scalblnl.c -- long double version of s_scalbn.c. |
| 2 | * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz. | |
| dfd2257a | 3 | */ |
| 9c84384c | 4 | |
| abfbdde1 | 5 | /* @(#)s_scalbn.c 5.1 93/09/24 */ |
| dfd2257a UD |
6 | /* |
| 7 | * ==================================================== | |
| 8 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. | |
| 9 | * | |
| 10 | * Developed at SunPro, a Sun Microsystems, Inc. business. | |
| 11 | * Permission to use, copy, modify, and distribute this | |
| 12 | * software is freely granted, provided that this notice | |
| 13 | * is preserved. | |
| 14 | * ==================================================== | |
| 15 | */ | |
| 16 | ||
| 17 | #if defined(LIBM_SCCS) && !defined(lint) | |
| 18 | static char rcsid[] = "$NetBSD: $"; | |
| 19 | #endif | |
| 20 | ||
| 21 | /* | |
| abfbdde1 UD |
22 | * scalblnl (long double x, long int n) |
| 23 | * scalblnl(x,n) returns x* 2**n computed by exponent | |
| dfd2257a UD |
24 | * manipulation rather than by actually performing an |
| 25 | * exponentiation or a multiplication. | |
| 26 | */ | |
| 27 | ||
| 1ed0291c RH |
28 | #include <math.h> |
| 29 | #include <math_private.h> | |
| dfd2257a | 30 | |
| 15089e04 | 31 | static const _Float128 |
| 02bbfb41 PM |
32 | two114 = L(2.0769187434139310514121985316880384E+34), /* 0x4071000000000000, 0 */ |
| 33 | twom114 = L(4.8148248609680896326399448564623183E-35), /* 0x3F8D000000000000, 0 */ | |
| 34 | huge = L(1.0E+4900), | |
| 35 | tiny = L(1.0E-4900); | |
| dfd2257a | 36 | |
| 15089e04 | 37 | _Float128 __scalblnl (_Float128 x, long int n) |
| dfd2257a | 38 | { |
| abfbdde1 UD |
39 | int64_t k,hx,lx; |
| 40 | GET_LDOUBLE_WORDS64(hx,lx,x); | |
| 41 | k = (hx>>48)&0x7fff; /* extract exponent */ | |
| dfd2257a | 42 | if (k==0) { /* 0 or subnormal x */ |
| abfbdde1 UD |
43 | if ((lx|(hx&0x7fffffffffffffffULL))==0) return x; /* +-0 */ |
| 44 | x *= two114; | |
| 45 | GET_LDOUBLE_MSW64(hx,x); | |
| 46 | k = ((hx>>48)&0x7fff) - 114; | |
| 47 | } | |
| dfd2257a | 48 | if (k==0x7fff) return x+x; /* NaN or Inf */ |
| abfbdde1 | 49 | if (n< -50000) return tiny*__copysignl(tiny,x); /*underflow*/ |
| a6d06d7b JM |
50 | if (n> 50000 || k+n > 0x7ffe) |
| 51 | return huge*__copysignl(huge,x); /* overflow */ | |
| 52 | /* Now k and n are bounded we know that k = k+n does not | |
| 53 | overflow. */ | |
| 54 | k = k+n; | |
| dfd2257a | 55 | if (k > 0) /* normal result */ |
| abfbdde1 UD |
56 | {SET_LDOUBLE_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48)); return x;} |
| 57 | if (k <= -114) | |
| 58 | return tiny*__copysignl(tiny,x); /*underflow*/ | |
| 59 | k += 114; /* subnormal result */ | |
| 60 | SET_LDOUBLE_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48)); | |
| 61 | return x*twom114; | |
| dfd2257a | 62 | } |