| /* @(#)s_frexp.c 5.1 93/09/24 */ |
| /* |
| * ==================================================== |
| * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| * |
| * Developed at SunPro, a Sun Microsystems, Inc. business. |
| * Permission to use, copy, modify, and distribute this |
| * software is freely granted, provided that this notice |
| * is preserved. |
| * ==================================================== |
| */ |
| |
| #include <sys/cdefs.h> |
| __FBSDID("$FreeBSD$"); |
| |
| /* |
| * for non-zero x |
| * x = frexp(arg,&exp); |
| * return a double fp quantity x such that 0.5 <= |x| <1.0 |
| * and the corresponding binary exponent "exp". That is |
| * arg = x*2^exp. |
| * If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg |
| * with *exp=0. |
| */ |
| |
| #include <float.h> |
| |
| #include "math.h" |
| #include "math_private.h" |
| |
| static const double |
| two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */ |
| |
| double |
| frexp(double x, int *eptr) |
| { |
| int32_t hx, ix, lx; |
| EXTRACT_WORDS(hx,lx,x); |
| ix = 0x7fffffff&hx; |
| *eptr = 0; |
| if(ix>=0x7ff00000||((ix|lx)==0)) return x; /* 0,inf,nan */ |
| if (ix<0x00100000) { /* subnormal */ |
| x *= two54; |
| GET_HIGH_WORD(hx,x); |
| ix = hx&0x7fffffff; |
| *eptr = -54; |
| } |
| *eptr += (ix>>20)-1022; |
| hx = (hx&0x800fffff)|0x3fe00000; |
| SET_HIGH_WORD(x,hx); |
| return x; |
| } |
| |
| #if (LDBL_MANT_DIG == 53) |
| __weak_reference(frexp, frexpl); |
| #endif |
