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[] = "$Id$"; 18 #endif 19 20 #include "math.h" 21 #include "math_private.h" 22 23 #ifdef __STDC__ 24 static const float 25 #else 26 static float 27 #endif 28 two25 = 3.355443200e+07, /* 0x4c000000 */ 29 twom25 = 2.9802322388e-08, /* 0x33000000 */ 30 huge = 1.0e+30, 31 tiny = 1.0e-30; 32 33 #ifdef __STDC__ 34 float scalbnf (float x, int n) 35 #else 36 float scalbn (x,n) 37 float x; int n; 38 #endif 39 { 40 int32_t k,ix; 41 GET_FLOAT_WORD(ix,x); 42 k = (ix&0x7f800000)>>23; /* extract exponent */ 43 if (k==0) { /* 0 or subnormal x */ 44 if ((ix&0x7fffffff)==0) return x; /* +-0 */ 45 x *= two25; 46 GET_FLOAT_WORD(ix,x); 47 k = ((ix&0x7f800000)>>23) - 25; 48 if (n< -50000) return tiny*x; /*underflow*/ 49 } 50 if (k==0xff) return x+x; /* NaN or Inf */ 51 k = k+n; 52 if (k > 0xfe) return huge*copysignf(huge,x); /* overflow */ 53 if (k > 0) /* normal result */ 54 {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;} 55 if (k <= -25) 56 if (n > 50000) /* in case integer overflow in n+k */ 57 return huge*copysignf(huge,x); /*overflow*/ 58 else return tiny*copysignf(tiny,x); /*underflow*/ 59 k += 25; /* subnormal result */ 60 SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); 61 return x*twom25; 62 } 63