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 /* 13 * for non-zero x 14 * x = frexp(arg,&exp); 15 * return a double fp quantity x such that 0.5 <= |x| <1.0 16 * and the corresponding binary exponent "exp". That is 17 * arg = x*2^exp. 18 * If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg 19 * with *exp=0. 20 */ 21 22 #include <float.h> 23 24 #include "math.h" 25 #include "math_private.h" 26 27 static const double 28 two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */ 29 30 double 31 frexp(double x, int *eptr) 32 { 33 int32_t hx, ix, lx; 34 EXTRACT_WORDS(hx,lx,x); 35 ix = 0x7fffffff&hx; 36 *eptr = 0; 37 if(ix>=0x7ff00000||((ix|lx)==0)) return x; /* 0,inf,nan */ 38 if (ix<0x00100000) { /* subnormal */ 39 x *= two54; 40 GET_HIGH_WORD(hx,x); 41 ix = hx&0x7fffffff; 42 *eptr = -54; 43 } 44 *eptr += (ix>>20)-1022; 45 hx = (hx&0x800fffff)|0x3fe00000; 46 SET_HIGH_WORD(x,hx); 47 return x; 48 } 49 50 #if (LDBL_MANT_DIG == 53) 51 __weak_reference(frexp, frexpl); 52 #endif 53