vx32

Local 9vx git repository for patches.
git clone git://r-36.net/vx32
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s_frexp.c (1328B)


      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 #ifndef lint
     14 static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_frexp.c,v 1.8 2002/05/28 18:15:04 alfred Exp $";
     15 #endif
     16 
     17 /*
     18  * for non-zero x
     19  *	x = frexp(arg,&exp);
     20  * return a double fp quantity x such that 0.5 <= |x| <1.0
     21  * and the corresponding binary exponent "exp". That is
     22  *	arg = x*2^exp.
     23  * If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg
     24  * with *exp=0.
     25  */
     26 
     27 #include "math.h"
     28 #include "math_private.h"
     29 
     30 static const double
     31 two54 =  1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */
     32 
     33 double
     34 frexp(double x, int *eptr)
     35 {
     36 	int32_t hx, ix, lx;
     37 	EXTRACT_WORDS(hx,lx,x);
     38 	ix = 0x7fffffff&hx;
     39 	*eptr = 0;
     40 	if(ix>=0x7ff00000||((ix|lx)==0)) return x;	/* 0,inf,nan */
     41 	if (ix<0x00100000) {		/* subnormal */
     42 	    x *= two54;
     43 	    GET_HIGH_WORD(hx,x);
     44 	    ix = hx&0x7fffffff;
     45 	    *eptr = -54;
     46 	}
     47 	*eptr += (ix>>20)-1022;
     48 	hx = (hx&0x800fffff)|0x3fe00000;
     49 	SET_HIGH_WORD(x,hx);
     50 	return x;
     51 }