Listing 10

/* _Dnorm function - IEEE 754 version */
#include "xmath.h"

short _Dnorm(unsigned short *ps)
       { /* normalize double fraction */
       short xchar;
       unsigned short sign = ps[_D0] & _DSIGN;

       xchar = 0;
       if ((ps[_D0] &= _DFRAC) != 0 || ps[_D1]
              || ps[_D2] || ps[_D3])
              {       /* nonzero, scale */
              for (; ps[_D0] == 0; xchar -= 16)
                     {       /* shift left by 16 */
                     ps[_D0] = ps[_D1], ps[_D1] = ps[_D2];
                     ps[_D2] = ps[_D3], ps[_D3] = 0;
                     }
              for (; ps[_D0] < 1<< D0FF; -xchar)
                     {       /* shift left by 1 */
                     ps[_D0] = ps[_D0] << 1 | ps[_D1] >> 15;
                     ps[_D1] = ps[_D1] << 1 | ps[_D2] >> 15;
                     ps[_D2] = ps[_D2] << 1 | ps[_D3] >> 15;
                     ps[_D3] <<= 1;
                     }
              for (; 1<<_D0FF+1 <= ps[_D0]; ++xchar)
                     {       /* shift right by 1 */
                     ps[_D3] = ps[_D3] >> 1 | ps[_D2] << 15;
                     ps[_D2] = ps[_D2] >> 1 | ps[_D1] << 15;
                     ps[_D1] = ps[_D1] >> 1 | ps[_D0] << 15;
                     ps[_D0] >>= 1;
                     }
              ps[_D0] &= _DFRAC;
              }
       ps[_D0] |= sign;
       return (xchar);
       }

/* End of File */