1 /* s_scalbnf.c -- float version of s_scalbn.c. 2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 3 */ 4 5 /* 6 * ==================================================== 7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8 * 9 * Developed at SunPro, a Sun Microsystems, Inc. business. 10 * Permission to use, copy, modify, and distribute this 11 * software is freely granted, provided that this notice 12 * is preserved. 13 * ==================================================== 14 */ 15 16 #ifndef lint 17 static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_scalbnf.c,v 1.8 2005/03/07 04:52:43 das Exp $"; 18 #endif 19 20 #include <sys/cdefs.h> 21 22 #include "math.h" 23 #include "math_private.h" 24 25 static const float 26 two25 = 3.355443200e+07, /* 0x4c000000 */ 27 twom25 = 2.9802322388e-08, /* 0x33000000 */ 28 huge = 1.0e+30, 29 tiny = 1.0e-30; 30 31 float 32 scalbnf (float x, int n) 33 { 34 int32_t k,ix; 35 GET_FLOAT_WORD(ix,x); 36 k = (ix&0x7f800000)>>23; /* extract exponent */ 37 if (k==0) { /* 0 or subnormal x */ 38 if ((ix&0x7fffffff)==0) return x; /* +-0 */ 39 x *= two25; 40 GET_FLOAT_WORD(ix,x); 41 k = ((ix&0x7f800000)>>23) - 25; 42 if (n< -50000) return tiny*x; /*underflow*/ 43 } 44 if (k==0xff) return x+x; /* NaN or Inf */ 45 k = k+n; 46 if (k > 0xfe) return huge*copysignf(huge,x); /* overflow */ 47 if (k > 0) /* normal result */ 48 {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;} 49 if (k <= -25) 50 if (n > 50000) /* in case integer overflow in n+k */ 51 return huge*copysignf(huge,x); /*overflow*/ 52 else return tiny*copysignf(tiny,x); /*underflow*/ 53 k += 25; /* subnormal result */ 54 SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); 55 return x*twom25; 56 } 57 58 __strong_reference(scalbnf, ldexpf); 59