s_scalbnf.c revision 8870
110216Sphk/* s_scalbnf.c -- float version of s_scalbn.c. 210216Sphk * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 310216Sphk */ 410216Sphk 510216Sphk/* 610216Sphk * ==================================================== 7139825Simp * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8139825Simp * 910216Sphk * Developed at SunPro, a Sun Microsystems, Inc. business. 1010216Sphk * Permission to use, copy, modify, and distribute this 1110216Sphk * software is freely granted, provided that this notice 1210216Sphk * is preserved. 1310216Sphk * ==================================================== 1410216Sphk */ 1510216Sphk 1610216Sphk#ifndef lint 1710216Sphkstatic char rcsid[] = "$Id: s_scalbnf.c,v 1.1.1.1 1994/08/19 09:39:58 jkh Exp $"; 1810216Sphk#endif 1910216Sphk 2010216Sphk#include "math.h" 2110216Sphk#include "math_private.h" 2210216Sphk 2310216Sphk#ifdef __STDC__ 2410216Sphkstatic const float 2510216Sphk#else 2610216Sphkstatic float 2710216Sphk#endif 2810216Sphktwo25 = 3.355443200e+07, /* 0x4c000000 */ 2910216Sphktwom25 = 2.9802322388e-08, /* 0x33000000 */ 3010216Sphkhuge = 1.0e+30, 3110216Sphktiny = 1.0e-30; 3259656Siwasaki 3359656Siwasaki#ifdef __STDC__ 3459656Siwasaki float scalbnf (float x, int n) 3510216Sphk#else 3610216Sphk float scalbn (x,n) 3710216Sphk float x; int n; 3810216Sphk#endif 3910216Sphk{ 4010216Sphk int32_t k,ix; 4110216Sphk GET_FLOAT_WORD(ix,x); 4210216Sphk k = (ix&0x7f800000)>>23; /* extract exponent */ 4310216Sphk if (k==0) { /* 0 or subnormal x */ 4410216Sphk if ((ix&0x7fffffff)==0) return x; /* +-0 */ 4510216Sphk x *= two25; 4610216Sphk GET_FLOAT_WORD(ix,x); 4710216Sphk k = ((ix&0x7f800000)>>23) - 25; 4810216Sphk if (n< -50000) return tiny*x; /*underflow*/ 4959656Siwasaki } 5059656Siwasaki if (k==0xff) return x+x; /* NaN or Inf */ 5159656Siwasaki k = k+n; 5210216Sphk if (k > 0xfe) return huge*copysignf(huge,x); /* overflow */ 5310216Sphk if (k > 0) /* normal result */ 5459656Siwasaki {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;} 5559656Siwasaki if (k <= -25) 5659656Siwasaki if (n > 50000) /* in case integer overflow in n+k */ 5759656Siwasaki return huge*copysignf(huge,x); /*overflow*/ 5859656Siwasaki else return tiny*copysignf(tiny,x); /*underflow*/ 5959656Siwasaki k += 25; /* subnormal result */ 6010216Sphk SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); 6110216Sphk return x*twom25; 6210216Sphk} 6310216Sphk