1 /* @(#)s_frexp.c 5.1 93/09/24 */ 2 /* 3 * ==================================================== 4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 5 * 6 * Developed at SunPro, a Sun Microsystems, Inc. business. 7 * Permission to use, copy, modify, and distribute this 8 * software is freely granted, provided that this notice 9 * is preserved. 10 * ==================================================== 11 */ 12 13 #include <sys/cdefs.h> 14 /* 15 * for non-zero x 16 * x = frexp(arg,&exp); 17 * return a double fp quantity x such that 0.5 <= |x| <1.0 18 * and the corresponding binary exponent "exp". That is 19 * arg = x*2^exp. 20 * If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg 21 * with *exp=0. 22 */ 23 24 #include <float.h> 25 26 #include "math.h" 27 #include "math_private.h" 28 29 static const double 30 two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */ 31 32 double 33 frexp(double x, int *eptr) 34 { 35 int32_t hx, ix, lx; 36 EXTRACT_WORDS(hx,lx,x); 37 ix = 0x7fffffff&hx; 38 *eptr = 0; 39 if(ix>=0x7ff00000||((ix|lx)==0)) return x; /* 0,inf,nan */ 40 if (ix<0x00100000) { /* subnormal */ 41 x *= two54; 42 GET_HIGH_WORD(hx,x); 43 ix = hx&0x7fffffff; 44 *eptr = -54; 45 } 46 *eptr += (ix>>20)-1022; 47 hx = (hx&0x800fffff)|0x3fe00000; 48 SET_HIGH_WORD(x,hx); 49 return x; 50 } 51 52 #if (LDBL_MANT_DIG == 53) 53 __weak_reference(frexp, frexpl); 54 #endif 55