def popcount(w):
"""
Create a population count circuit.
Parameters
----------
w: the width of the adder.
Returns
-------
a `CircuitGraph` addder.
"""
c = Circuit(name="popcount")
ps = [[c.add(f"in_{i}", "input")] for i in range(w)]
i = 0
while len(ps) > 1:
# get values
ns = ps.pop(0)
ms = ps.pop(0)
# pad
aw = max(len(ns), len(ms))
while len(ms) < aw:
ms += ["null"]
while len(ns) < aw:
ns += ["null"]
# instantiate and connect adder
a = adder(aw).strip_io()
c.extend(a.relabel({n: f"add_{i}_{n}" for n in a.nodes()}))
for j, (n, m) in enumerate(zip(ns, ms)):
c.connect(n, f"add_{i}_a_{j}")
c.connect(m, f"add_{i}_b_{j}")
# add adder outputs
ps.append([f"add_{i}_out_{j}" for j in range(aw + 1)])
i += 1
# connect outputs
for i, o in enumerate(ps[0]):
c.add(f"out_{i}", "buf", fanin=o, output=True)
if "null" in c:
c.set_type("null", "0")
c.set_output("null", False)
return c
def bench_to_circuit(bench, name):
"""
Creates a new Circuit from a bench string.
Parameters
----------
bench: str
bench code.
name: str
the module name.
Returns
-------
Circuit
the parsed circuit.
"""
# create circuit
c = Circuit(name=name)
# get inputs
in_regex = r"(?:INPUT|input)\s*\((.+?)\)"
for net_str in re.findall(in_regex, bench, re.DOTALL):
nets = net_str.replace(" ", "").replace("\n",
"").replace("\t",
"").split(",")
for n in nets:
c.add(n, "input")
# handle gates
regex = r"(\S+)\s*=\s*(NOT|OR|NOR|AND|NAND|XOR|XNOR|not|or|nor|and|nand|not|xor|xnor)\((.+?)\)"
for net, gate, input_str in re.findall(regex, bench):
# parse all nets
inputs = (input_str.replace(" ",
"").replace("\n",
"").replace("\t",
"").split(","))
# get outputs
in_regex = r"(?:OUTPUT|output)\s*\((.+?)\)"
for net_str in re.findall(in_regex, bench, re.DOTALL):
nets = net_str.replace(" ", "").replace("\n",
"").replace("\t",
"").split(",")
for n in nets:
c.set_output(n)
return c