lib/libm/src/w_powf.c

   1 /* w_powf.c -- float version of w_pow.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 <sys/cdefs.h>
  17 #if defined(LIBM_SCCS) && !defined(lint)
  18 __RCSID("$NetBSD: w_powf.c,v 1.6 2002/05/26 22:02:02 wiz Exp $");
  19 #endif
  20
  21 /*
  22  * wrapper powf(x,y) return x**y
  23  */
  24
  25 #include "math.h"
  26 #include "math_private.h"
  27
  28
  29 float
  30 powf(float x, float y)  /* wrapper powf */
  31 {
  32 #ifdef _IEEE_LIBM
  33         return  __ieee754_powf(x,y);
  34 #else
  35         float z;
  36         z=__ieee754_powf(x,y);
  37         if(_LIB_VERSION == _IEEE_|| isnanf(y)) return z;
  38         if(isnanf(x)) {
  39             if(y==(float)0.0)
  40                 /* powf(NaN,0.0) */
  41                 return (float)__kernel_standard((double)x,(double)y,142);
  42             else
  43                 return z;
  44         }
  45         if(x==(float)0.0){
  46             if(y==(float)0.0)
  47                 /* powf(0.0,0.0) */
  48                 return (float)__kernel_standard((double)x,(double)y,120);
  49             if(finitef(y)&&y<(float)0.0)
  50                 /* powf(0.0,negative) */
  51                 return (float)__kernel_standard((double)x,(double)y,123);
  52             return z;
  53         }
  54         if(!finitef(z)) {
  55             if(finitef(x)&&finitef(y)) {
  56                 if(isnanf(z))
  57                     /* powf neg**non-int */
  58                     return (float)__kernel_standard((double)x,(double)y,124);
  59                 else
  60                     /* powf overflow */
  61                     return (float)__kernel_standard((double)x,(double)y,121);
  62             }
  63         }
  64         if(z==(float)0.0&&finitef(x)&&finitef(y))
  65             /* powf underflow */
  66             return (float)__kernel_standard((double)x,(double)y,122);
  67         return z;
  68 #endif
  69 }