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- /* @(#)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.
- * ====================================================
- */
- #if defined(LIBM_SCCS) && !defined(lint)
- static char rcsid[] = "$NetBSD: s_frexp.c,v 1.9 1995/05/10 20:47:24 jtc Exp $";
- #endif
- /*
- * 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 "math.h"
- #include "math_private.h"
- #ifdef __STDC__
- static const double
- #else
- static double
- #endif
- two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */
- #ifdef __STDC__
- double frexp(double x, int *eptr)
- #else
- double frexp(x, eptr)
- double x; int *eptr;
- #endif
- {
- 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;
- }
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