campo-sirio/gfm/smi.c

/* 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"

void _SubUnsArr(src1, src2, n)
unsigned SHORT        src1[], src2[];
int             n;
{
  int i;
  unsigned long psrc;
  unsigned SHORT carry = 0;

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