//	routeArcLen.bcpl

//	 The memo-saving length routine used by the combinatorial
//  and heuristic wire routers

//	E. McCreight
//	last edited by McCreight, June 25, 1981  3:07 PM

get "route.defs"


static
	[ DistFn
	memoTable = empty
	]


let ArcLength(i, j) = valof

	[ if i eq j then resultis 0

	if i gr j then
		[ let t = i; i = j; j = t ]	// exchange i and j

	let memoKey = (i lshift 8)+j
	let memo = memoTable+
			((memoKey rem memoTableEntries) lshift 1)

	if memo>>MEMO.key eq memoKey then
		resultis memo>>MEMO.value

	memo>>MEMO.key = memoKey

	let value = DistFn(X!i, Y!i, X!j, Y!j)
	memo>>MEMO.value = value
	resultis value
	]
(635)\f1