industrialNETworX

The Standard C library that comes with the compiler (I assume it is the Hitex compiler) needs this. Hitex uses the newlib library as Standard C library.

Usually the variable "errno" is used as a global variable containing the error of the last function. See below for the sqrt function inside the newlib library (which can be downloaded from http://sourceware.org/newlib/).

The library expects "errno" (respectively __errno) to be provided by an O/S or the user.

/*
 * wrapper sqrt(x)
 */


#include "fdlibm.h"

#include 

#ifndef _DOUBLE_IS_32BITS

#ifdef __STDC__

        double sqrt(double x)           /* wrapper sqrt */

#else

        double sqrt(x)                  /* wrapper sqrt */

        double x;

#endif

{

#ifdef _IEEE_LIBM

        return __ieee754_sqrt(x);

#else

        struct exception exc;

        double z;

        z = __ieee754_sqrt(x);

        if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;

        if(x<0.0) {

          exc.type = DOMAIN;

          exc.name = "sqrt";

          exc.err = 0;

          exc.arg1 = exc.arg2 = x;

          if (_LIB_VERSION == _SVID_)

            exc.retval = 0.0;

          else

            exc.retval = 0.0/0.0;

          if (_LIB_VERSION == _POSIX_)

            errno = EDOM;

          else if (!matherr(&exc)) {

            errno = EDOM;

          }

          if (exc.err != 0)

            errno = exc.err;

          return exc.retval;

        } else

            return z;

#endif

}

#endif /* defined(_DOUBLE_IS_32BITS) */

Regards

MT