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