transform: unroll

examples/basic/multi_accumulator.py

@@ -0,0 +1,19 @@
+from migen.fhdl.structure import *
+from migen.transform.unroll import unroll_sync
+from migen.fhdl import verilog
+
+x = Signal(BV(4))
+y = Signal(BV(4))
+acc = Signal(BV(4))
+
+sync = [
+	acc.eq(acc + x + y)
+]
+
+n = 5
+xs = [Signal(BV(4)) for i in range(n)]
+ys = [Signal(BV(4)) for i in range(n)]
+accs = [Signal(BV(4)) for i in range(n)]
+
+sync_u = unroll_sync(sync, {x: xs, y: ys}, {acc: accs})
+print(verilog.convert(Fragment(sync=sync_u), ios=set(xs+ys+accs)))

migen/transform/unroll.py

@@ -0,0 +1,94 @@
+from migen.fhdl.structure import *
+from migen.fhdl.structure import _Operator, _Slice, _Assign, _ArrayProxy
+
+# y <= y + a + b
+#
+# unroll_sync(sync, {b: [b1, b2], c: [c1, c2]}, {y: [y1, y2]})
+#
+# ==>
+#
+# v_y1 = y2 + a1 + b1
+# v_y2 = v_y1 + a2 + b2
+# y1 <= v_y1
+# y2 <= v_y2
+
+(_UNDETERMINED, _IN, _OUT) = range(3)
+
+# TODO: arrays
+
+def _replace_if_in(d, s):
+	try:
+		return d[s]
+	except KeyError:
+		return s
+
+def _replace(node, rin, rout, mode=_UNDETERMINED):
+	if isinstance(node, Constant):
+		return node
+	elif isinstance(node, Signal):
+		if mode == _IN:
+			return _replace_if_in(rin, node)
+		elif mode == _OUT:
+			return _replace_if_in(rout, node)
+		else:
+			raise ValueError
+	elif isinstance(node, _Operator):
+		rop = [_replace(op, rin, rout, mode) for op in node.operands]
+		return _Operator(node.op, rop)
+	elif isinstance(node, _Slice):
+		return _Slice(_replace(node.value, rin, rout, mode), node.start, node.stop)
+	elif isinstance(node, Cat):
+		rcomp = [_replace(comp, rin, rout, mode) for comp in node.l]
+		return Cat(*rcomp)
+	elif isinstance(node, Replicate):
+		return Replicate(_replace(node.v, rin, rout, mode), node.n)
+	elif isinstance(node, _Assign):
+		return _Assign(_replace(node.l, rin, rout, _OUT), _replace(node.r, rin, rout, _IN))
+	elif isinstance(node, list):
+		return [_replace(s, rin, rout) for s in node]
+	elif isinstance(node, If):
+		r = If(_replace(node.cond, rin, rout, _IN))
+		r.t = _replace(node.t, rin, rout)
+		r.f = _replace(node.f, rin, rout)
+		return r
+	elif isinstance(node, Case):
+		r = Case(_replace(case.test, rin, rout, _IN))
+		r.cases = [(c[0], _replace(c[1], rin, rout)) for c in node.cases]
+		r.default = _replace(node.default, rin, rout)
+		return r
+	else:
+		raise TypeError
+
+def _list_step_dicts(d):
+	iterdict = dict((k, iter(v)) for k, v in d.items())
+	r = []
+	try:
+		while True:
+			r.append(dict([(k, next(i)) for k, i in iterdict.items()]))
+	except StopIteration:
+		pass
+	return r
+
+def _variable_for(s, n):
+	sn = s.backtrace[-1][0]
+	if isinstance(sn, str):
+		name = "v" + str(n) + "_" + sn
+	else:
+		name = "v"
+	return Signal(s.bv, name=name, variable=True)
+
+def unroll_sync(sync, inputs, outputs):
+	sd_in = _list_step_dicts(inputs)
+	sd_out = _list_step_dicts(outputs)
+
+	do_var_old = sd_out[-1]
+	r = []
+	for n, (di, do) in enumerate(zip(sd_in, sd_out)):
+		do_var = dict((k, _variable_for(v, n)) for k, v in do.items())
+		di_plus_do_var_old = di.copy()
+		di_plus_do_var_old.update(do_var_old)
+		r += _replace(sync, di_plus_do_var_old, do_var)
+		r += [v.eq(do_var[k]) for k, v in do.items()]
+		do_var_old = do_var
+
+	return r