#include "defs.h"


/* estimate extra length of wire required to interchange
 * chips c1 and c2.   To move c1 to c2 add delx and dely to
 * to the coordinates of c1.   c2 may be zero.
 * return immediately that it is obvious that the extra length
 * will be grater than lim.
 * Returned value is the estimated extra length.
 */

PIN	nvec[2*MAXPIN];	/* pointers to heads of nets */

L_INT netl(c1, c2, delx, dely, lim)
	CHP c1, c2;
	INT delx, dely;
	L_INT lim;
{
	REG PIN pp, opp;
	PIN p, hd, lopin, hipin;
	CHP ca, cb;
	PIN1 root;
	INT nd, psum, i;
	PIN *np;
	REG INT od;
	L_INT sum;

	ca = c1; 
	cb = c2;
	sum = 0;
	np = nvec;
	for (i = 0; i < 2; i++)
	{
		if (cb)
		{
			lopin = cb->pins;
			hipin = &cb->pins[cb->siz];
		}
		else	{
			/* no restriction on scan */
			lopin = Enets;
			hipin = nets;
		}
		if (ca) for (p = ca->pins; p < &ca->pins[ca->siz]; p++)
		{
			pp = p;
			hd = 0;
			*np = 0;
			do	{
				if ((pp->x & UNPLAC) == 0)
				{
					opp = pp;
					if (hd == 0 && pp != p)
						hd = pp;
				}
				pp = CHAIN(pp);
				if (pp >= lopin && pp < hipin)
					goto ignore;
				if (HEAD(pp))
					*np = (pp == p)? hd : pp;
			} 
			while (pp != p);
			if ((pp = hd) == 0)
				goto ignore;
			if (pp == opp && (p->x & UNPLAC) == 0)
			{
				sum += twodist(pp->x-p->x,pp->y-p->y,delx,dely);
				goto ignore;
			}
			if ((p->x & UNPLAC) == 0)
			{
				od = (HEAD(p)) ? 0 : wdist(p,opp);
				if (HEAD(pp) == 0)
				{
					od += wdist(p, pp);
					if (HEAD(p) == 0)
						od -= wdist(opp, pp);
				}
				sum -= od;
			}
			np++;
			continue;
ignore:
			*np++ = 0;
		}
		ca = c2; 
		cb = c1;
		delx = -delx; 
		dely = -dely;
	}
	if (sum >= lim) goto out;
	ca = c1; 
	np = nvec;
	for (i = 0; i < 2; i++)
	{
		if (ca) for (p = ca->pins; p < &ca->pins[ca->siz]; p++)
		{
			opp = hd = *np++;
			if (opp == 0) continue;
			root->x = p->x + delx;
			root->y = p->y + dely;
			od = psum = wdist(opp, root);
			for (pp = CHAIN(opp); pp != hd; pp = CHAIN(pp))
			{
				if (p == pp || pp->x & UNPLAC) continue;
				nd = wdist(root, pp);
				od = od + nd - wdist(pp, opp);
				if (od < psum) psum = od;
				od = nd;
				opp = pp;
			}
			if (psum < od) od = psum;
			sum += od;
			if (sum >= lim) goto out;
		}
		ca = c2;
		delx = -delx; 
		dely = -dely;
	}
out:
	return(sum);
}