[unix-history] / usr / src / cmd / refer / shell.c

shell (n, comp, exch)
	int (*comp)(), (*exch)();
/* SORTS UP.  IF THERE ARE NO EXCHANGES (IEX=0) ON A SWEEP
  THE COMPARISON GAP (IGAP) IS HALVED FOR THE NEXT SWEEP */
{
	int igap, iplusg, iex, i, imax;
	igap=n;
while (igap > 1)
	{
	igap /= 2;
	imax = n-igap;
	do
		{
		iex=0;
		for(i=0; i<imax; i++)
			{
			iplusg = i + igap;
			if ((*comp) (i, iplusg) ) continue;
			(*exch) (i, iplusg);
			iex=1;
			}
		} while (iex>0);
	}
}
Commit	Line	Data
aaa7ced1 BJ	1	shell (n, comp, exch)
	2	int (comp)(), (exch)();
	3	/* SORTS UP. IF THERE ARE NO EXCHANGES (IEX=0) ON A SWEEP
	4	THE COMPARISON GAP (IGAP) IS HALVED FOR THE NEXT SWEEP */
	5	{
	6	int igap, iplusg, iex, i, imax;
	7	igap=n;
	8	while (igap > 1)
	9	{
	10	igap /= 2;
	11	imax = n-igap;
	12	do
	13	{
	14	iex=0;
	15	for(i=0; i<imax; i++)
	16	{
	17	iplusg = i + igap;
	18	if ((*comp) (i, iplusg) ) continue;
	19	(*exch) (i, iplusg);
	20	iex=1;
	21	}
	22	} while (iex>0);
	23	}
	24	}