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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [newlib/] [libm/] [mathfp/] [sf_pow.c] - Blame information for rev 179

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Line No. Rev Author Line
1 148 jeremybenn 
 
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/* @(#)z_powf.c 1.0 98/08/13 */
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#include <float.h>
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#include "fdlibm.h"
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#include "zmath.h"
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float powf (float x, float y)
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{
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  float d, k, t, r = 1.0;
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  int n, sign, exponent_is_even_int = 0;
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  __int32_t px;
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  GET_FLOAT_WORD (px, x);
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  k = modff (y, &d);
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  if (k == 0.0)
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    {
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      /* Exponent y is an integer. */
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      if (modff (ldexpf (y, -1), &t))
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        {
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          /* y is odd. */
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          exponent_is_even_int = 0;
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        }
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      else
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        {
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          /* y is even. */
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          exponent_is_even_int = 1;
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        }
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    }
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  if (x == 0.0)
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    {
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      if (y <= 0.0)
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        errno = EDOM;
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    }
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  else if ((t = y * log (fabsf (x))) >= BIGX)
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    {
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      errno = ERANGE;
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      if (px & 0x80000000)
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        {
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          /* x is negative. */
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          if (k)
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            {
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              /* y is not an integer. */
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              errno = EDOM;
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              x = 0.0;
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            }
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          else if (exponent_is_even_int)
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            x = z_infinity_f.f;
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          else
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            x = -z_infinity_f.f;
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        }
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    else
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      {
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        x = z_infinity_f.f;
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      }
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    }
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  else if (t < SMALLX)
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    {
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      errno = ERANGE;
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      x = 0.0;
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    }
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  else
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    {
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      if ( !k && fabsf (d) <= 32767 )
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        {
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          n = (int) d;
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          if ((sign = (n < 0)))
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            n = -n;
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          while ( n > 0 )
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            {
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              if ((unsigned int) n % 2)
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                r *= x;
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              x *= x;
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              n = (unsigned int) n / 2;
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            }
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          if (sign)
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            r = 1.0 / r;
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          return r;
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        }
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      else
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        {
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          if ( px & 0x80000000 )
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            {
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              /* x is negative. */
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              if (k)
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                {
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                  /* y is not an integer. */
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                  errno = EDOM;
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                  return 0.0;
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                }
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            }
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          x = exp (t);
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          if (!exponent_is_even_int)
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            {
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              if (px & 0x80000000)
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                {
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                  /* y is an odd integer, and x is negative,
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                     so the result is negative. */
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                  GET_FLOAT_WORD (px, x);
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                  px |= 0x80000000;
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                  SET_FLOAT_WORD (x, px);
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                }
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            }
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        }
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    }
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  return x;
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}
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#ifdef _DOUBLE_IS_32BITS
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double pow (double x, double y)
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{
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  return (double) powf ((float) x, (float) y);
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}
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#endif /* defined(_DOUBLE_IS_32BITS) */

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