/* void _SubUnsArr(src1,src2,n)
 *
 * ARGUMENT
 *      unsigned        *src1, *src2;
 *      int             n;
 *
 * DESCRIPTION
 *      Subtracts src2 from src1 putting the result in src1. It's assumed
 *  that caller has checked to assure that src1>src2 so no borrow can ever
 *  be generate (that's why this is a void!!).
 *
 * SIDE EFFECTS
 *      The original value of src1 is destroyed.
 *
 * RETURNS
 *      None.
 *
 * AUTHOR
 *      Brugnoli Giugno 1992
 *
 * MODIFICATIONS
 *
 */

#include <stdio.h>
#include <math.h>
#include "gm.h"
#include "gmsystem.h"

extern double pow(double, double);

void _SubUnsArr(src1, src2, n)
unsigned SHORT        src1[], src2[];
int             n;
{
  int i;
  unsigned long psrc,maxunsint;
  unsigned SHORT carry;

  carry=0;
#ifdef SH_LIB
	maxunsint=1;
	for (i=1;i<=BITSPERUI;i++) maxunsint*=2;
	maxunsint--;
#else
  maxunsint=(unsigned long)pow(2.,(float)BITSPERUI)-1;
#endif

  if (n>0)
    {
    for (i=0;i<n;i++)
      {
      if (src2[i]>src1[i])
        {
        psrc=maxunsint+0x1L+(long)src1[i]-(long)carry;
        carry=1;
        }
      else
        {
        psrc=src1[i]-carry;
        carry=0;
        }
      src1[i]=(unsigned SHORT)(psrc-(unsigned long)src2[i]);
      }
    }
}