| /* sf_scalbn.c -- float version of s_scalbn.c. |
| * Conversion to float by Ian Lance Taylor, Cygnus Support, [email protected]. |
| */ |
| |
| /* |
| * ==================================================== |
| * 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*/ |
| } |
| 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) { |
| if (n > OVERFLOW_INT) /* in case integer overflow in n+k */ |
| return huge*copysignf(huge,x); /*overflow*/ |
| else 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) */ |
