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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, t, r = 1.0;
  int n, k, sign = 0;
  __int32_t px;
 
  GET_FLOAT_WORD (px, x);
 
  k = modff (y, &d);
  if (k == 0.0)
    {
      if (modff (ldexpf (y, -1), &t))
        sign = 0;
      else
        sign = 1;
    }
 
  if (x == 0.0 && y <= 0.0)
    errno = EDOM;
 
  else if ((t = y * log (fabsf (x))) >= BIGX)
    {
      errno = ERANGE;
      if (px & 0x80000000)
        {
          if (!k)
            {
              errno = EDOM;
              x = 0.0;
            }
          else if (sign)
            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 )
            {
              if ( !k )
                {
                  errno = EDOM;
                  return 0.0;
                }
            }
 
          x = exp (t);
 
          if ( sign )
            {
              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	56	joel
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, t, r = 1.0;`
10			`int n, k, sign = 0;`
11			`__int32_t px;`
12
13			`GET_FLOAT_WORD (px, x);`
14
15			`k = modff (y, &d);`
16			`if (k == 0.0)`
17			`{`
18			`if (modff (ldexpf (y, -1), &t))`
19			`sign = 0;`
20			`else`
21			`sign = 1;`
22			`}`
23
24			`if (x == 0.0 && y <= 0.0)`
25			`errno = EDOM;`
26
27			`else if ((t = y * log (fabsf (x))) >= BIGX)`
28			`{`
29			`errno = ERANGE;`
30			`if (px & 0x80000000)`
31			`{`
32			`if (!k)`
33			`{`
34			`errno = EDOM;`
35			`x = 0.0;`
36			`}`
37			`else if (sign)`
38			`x = -z_infinity_f.f;`
39			`else`
40			`x = z_infinity_f.f;`
41			`}`
42
43			`else`
44			`x = z_infinity_f.f;`
45			`}`
46
47			`else if (t < SMALLX)`
48			`{`
49			`errno = ERANGE;`
50			`x = 0.0;`
51			`}`
52
53			`else`
54			`{`
55			`if ( k && fabsf (d) <= 32767 )`
56			`{`
57			`n = (int) d;`
58
59			`if (sign = (n < 0))`
60			`n = -n;`
61
62			`while ( n > 0 )`
63			`{`
64			`if ((unsigned int) n % 2)`
65			`r *= x;`
66			`x *= x;`
67			`n = (unsigned int) n / 2;`
68			`}`
69
70			`if (sign)`
71			`r = 1.0 / r;`
72
73			`return r;`
74			`}`
75
76			`else`
77			`{`
78			`if ( px & 0x80000000 )`
79			`{`
80			`if ( !k )`
81			`{`
82			`errno = EDOM;`
83			`return 0.0;`
84			`}`
85			`}`
86
87			`x = exp (t);`
88
89			`if ( sign )`
90			`{`
91			`px ^= 0x80000000;`
92			`SET_FLOAT_WORD (x, px);`
93			`}`
94			`}`
95			`}`
96
97			`return x;`
98			`}`
99
100			`#ifdef _DOUBLE_IS_32BITS`
101
102			`double pow (double x, double y)`
103			`{`
104			`return (double) powf ((float) x, (float) y);`
105			`}`
106
107			`#endif /* defined(_DOUBLE_IS_32BITS) */`

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