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