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  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) */
  72.