s_scalbnf.c revision 8870
12116Sjkh/* s_scalbnf.c -- float version of s_scalbn.c. 22116Sjkh * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 32116Sjkh */ 42116Sjkh 52116Sjkh/* 62116Sjkh * ==================================================== 72116Sjkh * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 82116Sjkh * 92116Sjkh * Developed at SunPro, a Sun Microsystems, Inc. business. 102116Sjkh * Permission to use, copy, modify, and distribute this 118870Srgrimes * software is freely granted, provided that this notice 122116Sjkh * is preserved. 132116Sjkh * ==================================================== 142116Sjkh */ 152116Sjkh 162116Sjkh#ifndef lint 178870Srgrimesstatic char rcsid[] = "$Id: s_scalbnf.c,v 1.1.1.1 1994/08/19 09:39:58 jkh Exp $"; 182116Sjkh#endif 192116Sjkh 202116Sjkh#include "math.h" 212116Sjkh#include "math_private.h" 222116Sjkh 232116Sjkh#ifdef __STDC__ 242116Sjkhstatic const float 252116Sjkh#else 262116Sjkhstatic float 272116Sjkh#endif 282116Sjkhtwo25 = 3.355443200e+07, /* 0x4c000000 */ 292116Sjkhtwom25 = 2.9802322388e-08, /* 0x33000000 */ 302116Sjkhhuge = 1.0e+30, 312116Sjkhtiny = 1.0e-30; 322116Sjkh 332116Sjkh#ifdef __STDC__ 342116Sjkh float scalbnf (float x, int n) 352116Sjkh#else 362116Sjkh float scalbn (x,n) 372116Sjkh float x; int n; 382116Sjkh#endif 392116Sjkh{ 402116Sjkh int32_t k,ix; 412116Sjkh GET_FLOAT_WORD(ix,x); 422116Sjkh k = (ix&0x7f800000)>>23; /* extract exponent */ 432116Sjkh if (k==0) { /* 0 or subnormal x */ 442116Sjkh if ((ix&0x7fffffff)==0) return x; /* +-0 */ 452116Sjkh x *= two25; 462116Sjkh GET_FLOAT_WORD(ix,x); 478870Srgrimes k = ((ix&0x7f800000)>>23) - 25; 482116Sjkh if (n< -50000) return tiny*x; /*underflow*/ 492116Sjkh } 502116Sjkh if (k==0xff) return x+x; /* NaN or Inf */ 518870Srgrimes k = k+n; 522116Sjkh if (k > 0xfe) return huge*copysignf(huge,x); /* overflow */ 532116Sjkh if (k > 0) /* normal result */ 542116Sjkh {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;} 552116Sjkh if (k <= -25) 562116Sjkh if (n > 50000) /* in case integer overflow in n+k */ 572116Sjkh return huge*copysignf(huge,x); /*overflow*/ 582116Sjkh else return tiny*copysignf(tiny,x); /*underflow*/ 592116Sjkh k += 25; /* subnormal result */ 602116Sjkh SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); 612116Sjkh return x*twom25; 622116Sjkh} 63