corelogic: operator tree

migen/bus/wishbone.py

@@ -1,5 +1,6 @@
 from migen.fhdl.structure import *
-from migen.corelogic import roundrobin, multimux
+from migen.corelogic import roundrobin
+from migen.corelogic.misc import multimux, optree
 from migen.bus.simple import Simple, get_sig_name
 
 _desc = [
@@ -37,7 +38,7 @@ class Arbiter:
 		m2s_names = [get_sig_name(x, False) for x in _desc if x[0]]
 		m2s_masters = [[getattr(m, name) for name in m2s_names] for m in self.masters]
 		m2s_target = [getattr(self.target, name) for name in m2s_names]
-		comb += multimux.multimux(self.rr.grant, m2s_masters, m2s_target)
+		comb += multimux(self.rr.grant, m2s_masters, m2s_target)
 		
 		# connect slave->master signals
 		s2m_names = [get_sig_name(x, False) for x in _desc if not x[0]]
@@ -115,21 +116,12 @@ class Decoder:
 			i += 1
 		
 		# generate master ack (resp. err) by ORing all slave acks (resp. errs)
-		ackv = Constant(0)
+		comb.append(self.master.ack_i.eq(optree('|', [slave[1].ack_o for slave in self.slaves])))
-		errv = Constant(0)
+		comb.append(self.master.err_i.eq(optree('|', [slave[1].err_o for slave in self.slaves])))
-		for slave in self.slaves:
-			ackv = ackv | slave[1].ack_o
-			errv = errv | slave[1].err_o
-		comb.append(self.master.ack_i.eq(ackv))
-		comb.append(self.master.err_i.eq(errv))
 		
 		# mux (1-hot) slave data return
-		i = 0
+		masked = [Replicate(slave_sel_r[i], self.master.dat_i.bv.width) & self.slaves[i][1].dat_o for i in range(len(self.slaves))]
-		datav = Constant(0, self.master.dat_i.bv)
+		comb.append(self.master.dat_i.eq(optree('|', masked)))
-		for slave in self.slaves:
-			datav = datav | (Replicate(slave_sel_r[i], self.master.dat_i.bv.width) & slave[1].dat_o)
-			i += 1
-		comb.append(self.master.dat_i.eq(datav))
 		
 		return Fragment(comb, sync)
 

migen/corelogic/misc.py

@@ -0,0 +1,33 @@
+from migen.fhdl.structure import *
+from migen.fhdl.structure import _Operator
+
+def multimux(sel, inputs, output):
+	n = len(inputs)
+	i = 0
+	comb = []
+	for osig in output:
+		choices = [x[i] for x in inputs]
+		cases = [[Constant(j, sel.bv), osig.eq(choices[j])] for j in range(n)]
+		cases[n-1][0] = Default()
+		comb.append(Case(sel, *cases))
+		i += 1
+	return comb
+
+def optree(op, operands, lb=None, ub=None, default=None):
+	if lb is None:
+		lb = 0
+	if ub is None:
+		ub = len(operands)
+	l = ub - lb
+	if l == 0:
+		if default is None:
+			raise AttributeError
+		else:
+			return default
+	elif l == 1:
+		return operands[lb]
+	else:
+		s = lb + l//2
+		return _Operator(op,
+			[optree(op, operands, lb, s, default),
+			optree(op, operands, s, ub, default)])

migen/corelogic/multimux.py

@@ -1,13 +0,0 @@
-from migen.fhdl.structure import *
-
-def multimux(sel, inputs, output):
-	n = len(inputs)
-	i = 0
-	comb = []
-	for osig in output:
-		choices = [x[i] for x in inputs]
-		cases = [[Constant(j, sel.bv), osig.eq(choices[j])] for j in range(n)]
-		cases[n-1][0] = Default()
-		comb.append(Case(sel, *cases))
-		i += 1
-	return comb