/* _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<<_DOFF; --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<<_DOFF+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);
        }

