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 #include "math.h" 17 #include "math_private.h" 18 19 static const float 20 two25 = 3.355443200e+07, /* 0x4c000000 */ 21 twom25 = 2.9802322388e-08, /* 0x33000000 */ 22 huge = 1.0e+30, 23 tiny = 1.0e-30; 24 25 float 26 scalbnf(float x, int n) 27 { 28 int32_t k,ix; 29 GET_FLOAT_WORD(ix,x); 30 k = (ix&0x7f800000)>>23; /* extract exponent */ 31 if (k==0) { /* 0 or subnormal x */ 32 if ((ix&0x7fffffff)==0) return x; /* +-0 */ 33 x *= two25; 34 GET_FLOAT_WORD(ix,x); 35 k = ((ix&0x7f800000)>>23) - 25; 36 if (n< -50000) return tiny*x; /*underflow*/ 37 } 38 if (k==0xff) return x+x; /* NaN or Inf */ 39 k = k+n; 40 if (k > 0xfe) return huge*copysignf(huge,x); /* overflow */ 41 if (k > 0) /* normal result */ 42 {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;} 43 if (k <= -25) 44 if (n > 50000) /* in case integer overflow in n+k */ 45 return huge*copysignf(huge,x); /*overflow*/ 46 else return tiny*copysignf(tiny,x); /*underflow*/ 47 k += 25; /* subnormal result */ 48 SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); 49 return x*twom25; 50 } 51 DEF_STD(scalbnf); 52 53 float 54 ldexpf(float x, int n) 55 { 56 return scalbnf(x, n); 57 } 58