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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [mathfp/] [sf_pow.c] - Blame information for rev 258

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/* @(#)z_powf.c 1.0 98/08/13 */
#include <float.h>
#include "fdlibm.h"
#include "zmath.h"
 
float powf (float x, float y)
{
  float d, k, t, r = 1.0;
  int n, sign, exponent_is_even_int = 0;
  __int32_t px;
 
  GET_FLOAT_WORD (px, x);
 
  k = modff (y, &d);
 
  if (k == 0.0)
    {
      /* Exponent y is an integer. */
      if (modff (ldexpf (y, -1), &t))
        {
          /* y is odd. */
          exponent_is_even_int = 0;
        }
      else
        {
          /* y is even. */
          exponent_is_even_int = 1;
        }
    }
 
  if (x == 0.0)
    {
      if (y <= 0.0)
        errno = EDOM;
    }
  else if ((t = y * log (fabsf (x))) >= BIGX)
    {
      errno = ERANGE;
      if (px & 0x80000000)
        {
          /* x is negative. */
          if (k)
            {
              /* y is not an integer. */
              errno = EDOM;
              x = 0.0;
            }
          else if (exponent_is_even_int)
            x = z_infinity_f.f;
          else
            x = -z_infinity_f.f;
        }
    else
      {
        x = z_infinity_f.f;
      }
    }
  else if (t < SMALLX)
    {
      errno = ERANGE;
      x = 0.0;
    }
  else
    {
      if ( !k && fabsf (d) <= 32767 )
        {
          n = (int) d;
 
          if ((sign = (n < 0)))
            n = -n;
 
          while ( n > 0 )
            {
              if ((unsigned int) n % 2)
                r *= x;
              x *= x;
              n = (unsigned int) n / 2;
            }
 
          if (sign)
            r = 1.0 / r;
 
          return r;
        }
      else
        {
          if ( px & 0x80000000 )
            {
              /* x is negative. */
              if (k)
                {
                  /* y is not an integer. */
                  errno = EDOM;
                  return 0.0;
                }
            }
 
          x = exp (t);
 
          if (!exponent_is_even_int)
            {
              if (px & 0x80000000)
                {
                  /* y is an odd integer, and x is negative,
                     so the result is negative. */
                  GET_FLOAT_WORD (px, x);
                  px |= 0x80000000;
                  SET_FLOAT_WORD (x, px);
                }
            }
        }
    }
 
  return x;
}
 
#ifdef _DOUBLE_IS_32BITS
 
double pow (double x, double y)
{
  return (double) powf ((float) x, (float) y);
}
 
#endif /* defined(_DOUBLE_IS_32BITS) */ 

Line No.	Rev	Author	Line
1	207	jeremybenn
2			`/* @(#)z_powf.c 1.0 98/08/13 */`
3			`#include <float.h>`
4			`#include "fdlibm.h"`
5			`#include "zmath.h"`
6
7			`float powf (float x, float y)`
8			`{`
9			`float d, k, t, r = 1.0;`
10			`int n, sign, exponent_is_even_int = 0;`
11			`__int32_t px;`
12
13			`GET_FLOAT_WORD (px, x);`
14
15			`k = modff (y, &d);`
16
17			`if (k == 0.0)`
18			`{`
19			`/* Exponent y is an integer. */`
20			`if (modff (ldexpf (y, -1), &t))`
21			`{`
22			`/* y is odd. */`
23			`exponent_is_even_int = 0;`
24			`}`
25			`else`
26			`{`
27			`/* y is even. */`
28			`exponent_is_even_int = 1;`
29			`}`
30			`}`
31
32			`if (x == 0.0)`
33			`{`
34			`if (y <= 0.0)`
35			`errno = EDOM;`
36			`}`
37			`else if ((t = y * log (fabsf (x))) >= BIGX)`
38			`{`
39			`errno = ERANGE;`
40			`if (px & 0x80000000)`
41			`{`
42			`/* x is negative. */`
43			`if (k)`
44			`{`
45			`/* y is not an integer. */`
46			`errno = EDOM;`
47			`x = 0.0;`
48			`}`
49			`else if (exponent_is_even_int)`
50			`x = z_infinity_f.f;`
51			`else`
52			`x = -z_infinity_f.f;`
53			`}`
54			`else`
55			`{`
56			`x = z_infinity_f.f;`
57			`}`
58			`}`
59			`else if (t < SMALLX)`
60			`{`
61			`errno = ERANGE;`
62			`x = 0.0;`
63			`}`
64			`else`
65			`{`
66			`if ( !k && fabsf (d) <= 32767 )`
67			`{`
68			`n = (int) d;`
69
70			`if ((sign = (n < 0)))`
71			`n = -n;`
72
73			`while ( n > 0 )`
74			`{`
75			`if ((unsigned int) n % 2)`
76			`r *= x;`
77			`x *= x;`
78			`n = (unsigned int) n / 2;`
79			`}`
80
81			`if (sign)`
82			`r = 1.0 / r;`
83
84			`return r;`
85			`}`
86			`else`
87			`{`
88			`if ( px & 0x80000000 )`
89			`{`
90			`/* x is negative. */`
91			`if (k)`
92			`{`
93			`/* y is not an integer. */`
94			`errno = EDOM;`
95			`return 0.0;`
96			`}`
97			`}`
98
99			`x = exp (t);`
100
101			`if (!exponent_is_even_int)`
102			`{`
103			`if (px & 0x80000000)`
104			`{`
105			`/* y is an odd integer, and x is negative,`
106			`so the result is negative. */`
107			`GET_FLOAT_WORD (px, x);`
108			`px \|= 0x80000000;`
109			`SET_FLOAT_WORD (x, px);`
110			`}`
111			`}`
112			`}`
113			`}`
114
115			`return x;`
116			`}`
117
118			`#ifdef _DOUBLE_IS_32BITS`
119
120			`double pow (double x, double y)`
121			`{`
122			`return (double) powf ((float) x, (float) y);`
123			`}`
124
125			`#endif /* defined(_DOUBLE_IS_32BITS) */`

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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [mathfp/] [sf_pow.c] - Blame information for rev 258