/* sf_scalbn.c -- float version of s_scalbn.c. * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunPro, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== */ #include "fdlibm.h" #include <limits.h> #include <float.h> #if INT_MAX > 50000 #define OVERFLOW_INT 50000 #else #define OVERFLOW_INT 30000 #endif #ifdef __STDC__ static const float #else static float #endif two25 = 3.355443200e+07, /* 0x4c000000 */ twom25 = 2.9802322388e-08, /* 0x33000000 */ huge = 1.0e+30, tiny = 1.0e-30; #ifdef __STDC__ float scalbnf (float x, int n) #else float scalbnf (x,n) float x; int n; #endif { __int32_t k,ix; __uint32_t hx; GET_FLOAT_WORD(ix,x); hx = ix&0x7fffffff; k = hx>>23; /* extract exponent */ if (FLT_UWORD_IS_ZERO(hx)) return x; if (!FLT_UWORD_IS_FINITE(hx)) return x+x; /* NaN or Inf */ if (FLT_UWORD_IS_SUBNORMAL(hx)) { x *= two25; GET_FLOAT_WORD(ix,x); k = ((ix&0x7f800000)>>23) - 25; if (n< -50000) return tiny*x; /*underflow*/ } if (n > OVERFLOW_INT) /* in case integer overflow in n+k */ return huge*copysignf(huge,x); /*overflow*/ k = k+n; if (k > FLT_LARGEST_EXP) return huge*copysignf(huge,x); /* overflow */ if (k > 0) /* normal result */ {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;} if (k < FLT_SMALLEST_EXP) return tiny*copysignf(tiny,x); /*underflow*/ k += 25; /* subnormal result */ SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x*twom25; } #ifdef _DOUBLE_IS_32BITS #ifdef __STDC__ double scalbn(double x, int n) #else double scalbn(x,n) double x; int n; #endif { return (double) scalbnf((float) x, n); } #endif /* defined(_DOUBLE_IS_32BITS) */