newlib/libm/common/sf_scalbln.c

   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 "fdlibm.h"
  17
  18 #ifdef __STDC__
  19 static const float
  20 #else
  21 static float
  22 #endif
  23 two25   =  3.355443200e+07,     /* 0x4c000000 */
  24 twom25  =  2.9802322388e-08,    /* 0x33000000 */
  25 huge   = 1.0e+30,
  26 tiny   = 1.0e-30;
  27
  28 #ifdef __STDC__
  29         float scalblnf (float x, long int n)
  30 #else
  31         float scalblnf (x,n)
  32         float x; long int n;
  33 #endif
  34 {
  35         __int32_t k,ix;
  36         GET_FLOAT_WORD(ix,x);
  37         k = (ix&0x7f800000)>>23;                /* extract exponent */
  38         if (k==0) {                             /* 0 or subnormal x */
  39             if ((ix&0x7fffffff)==0) return x; /* +-0 */
  40             x *= two25;
  41             GET_FLOAT_WORD(ix,x);
  42             k = ((ix&0x7f800000)>>23) - 25;
  43             }
  44         if (k==0xff) return x+x;                /* NaN or Inf */
  45         k = k+n;
  46         if (n> 50000 || k >  0xfe)
  47           return huge*copysignf(huge,x); /* overflow  */
  48         if (n< -50000)
  49           return tiny*copysignf(tiny,x);        /*underflow*/
  50         if (k > 0)                              /* normal result */
  51             {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;}
  52         if (k <= -25)
  53             return tiny*copysignf(tiny,x);      /*underflow*/
  54         k += 25;                                /* subnormal result */
  55         SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23));
  56         return x*twom25;
  57 }
  58
  59 #ifdef _DOUBLE_IS_32BITS
  60
  61 #ifdef __STDC__
  62         double scalbln (double x, long int n)
  63 #else
  64         double scalbln (x,n)
  65         double x; long int n;
  66 #endif
  67 {
  68         return (double) scalblnf((float) x, n);
  69 }
  70
  71 #endif /* defined(_DOUBLE_IS_32BITS) */