From b9b156489868e5114577fd8b5089bad3ea2ee744 Mon Sep 17 00:00:00 2001
From: Oscar Gustafsson <oscar.gustafsson@gmail.com>
Date: Mon, 17 Apr 2023 14:45:00 +0200
Subject: [PATCH] Add support for bi-reciprocal LWDF
---
b_asic/sfg_generators.py | 81 ++++++++++++++++++++++---------------
test/test_sfg_generators.py | 23 +++++++++++
2 files changed, 71 insertions(+), 33 deletions(-)
diff --git a/b_asic/sfg_generators.py b/b_asic/sfg_generators.py
index c9435e23..87538704 100644
--- a/b_asic/sfg_generators.py
+++ b/b_asic/sfg_generators.py
@@ -29,6 +29,8 @@ def wdf_allpass(
Generate a signal flow graph of a WDF allpass section based on symmetric two-port\
adaptors.
+ Simplifies the SFG in case an adaptor operation is 0.
+
Parameters
----------
coefficients : 1D-array
@@ -62,17 +64,20 @@ def wdf_allpass(
output = Output()
odd_order = order % 2
if odd_order:
- # First-order section
- adaptor0 = SymmetricTwoportAdaptor(
- np_coefficients[0],
- input_op,
- latency=latency,
- latency_offsets=latency_offsets,
- execution_time=execution_time,
- )
- signal_out = Signal(adaptor0.output(0))
- delay = Delay(adaptor0.output(1))
- Signal(delay, adaptor0.input(1))
+ if np_coefficients[0]:
+ # First-order section
+ adaptor0 = SymmetricTwoportAdaptor(
+ np_coefficients[0],
+ input_op,
+ latency=latency,
+ latency_offsets=latency_offsets,
+ execution_time=execution_time,
+ )
+ signal_out = Signal(adaptor0.output(0))
+ delay = Delay(adaptor0.output(1))
+ Signal(delay, adaptor0.input(1))
+ else:
+ signal_out = Delay(input_op)
else:
signal_out = Signal(input_op)
@@ -80,28 +85,38 @@ def wdf_allpass(
sos_count = (order - 1) // 2 if odd_order else order // 2
offset1, offset2 = (1, 2) if odd_order else (0, 1)
for n in range(sos_count):
- adaptor1 = SymmetricTwoportAdaptor(
- np_coefficients[2 * n + offset1],
- signal_out,
- latency=latency,
- latency_offsets=latency_offsets,
- execution_time=execution_time,
- )
- # Signal(prev_adaptor., adaptor1.input(0), name="Previous-stage to next")
- delay1 = Delay(adaptor1.output(1))
- delay2 = Delay()
- adaptor2 = SymmetricTwoportAdaptor(
- np_coefficients[2 * n + offset2],
- delay1,
- delay2,
- latency=latency,
- latency_offsets=latency_offsets,
- execution_time=execution_time,
- )
- Signal(adaptor2.output(0), adaptor1.input(1))
- Signal(adaptor2.output(1), delay2)
- signal_out = Signal(adaptor1.output(0))
-
+ if np_coefficients[2 * n + offset1]:
+ adaptor1 = SymmetricTwoportAdaptor(
+ np_coefficients[2 * n + offset1],
+ signal_out,
+ latency=latency,
+ latency_offsets=latency_offsets,
+ execution_time=execution_time,
+ )
+ # Signal(prev_adaptor., adaptor1.input(0), name="Previous-stage to next")
+ delay1 = Delay(adaptor1.output(1))
+ else:
+ delay1 = Delay(signal_out)
+ if np_coefficients[2 * n + offset2]:
+ delay2 = Delay()
+ adaptor2 = SymmetricTwoportAdaptor(
+ np_coefficients[2 * n + offset2],
+ delay1,
+ delay2,
+ latency=latency,
+ latency_offsets=latency_offsets,
+ execution_time=execution_time,
+ )
+ Signal(adaptor2.output(0), adaptor1.input(1))
+ Signal(adaptor2.output(1), delay2)
+ signal_out = Signal(adaptor1.output(0))
+ else:
+ delay2 = Delay(delay1)
+ if np_coefficients[2 * n + offset1]:
+ Signal(delay2, adaptor1.input(1))
+ signal_out = Signal(adaptor1.output(0))
+ else:
+ signal_out = Signal(delay2)
output << signal_out
return SFG([input_op], [output], name=Name(name))
diff --git a/test/test_sfg_generators.py b/test/test_sfg_generators.py
index 78ca06f4..31293462 100644
--- a/test/test_sfg_generators.py
+++ b/test/test_sfg_generators.py
@@ -73,6 +73,29 @@ def test_wdf_allpass():
== 1
)
+ # Bi-reciprocal third-order
+ sfg = wdf_allpass([0.0, 0.5, 0.0])
+ assert (
+ len(
+ [
+ comp
+ for comp in sfg.components
+ if isinstance(comp, SymmetricTwoportAdaptor)
+ ]
+ )
+ == 1
+ )
+
+ assert len([comp for comp in sfg.components if isinstance(comp, Delay)]) == 3
+
+ # Second-order all zeros third-order
+ sfg = wdf_allpass([0.0, 0.0])
+ assert not [
+ comp for comp in sfg.components if isinstance(comp, SymmetricTwoportAdaptor)
+ ]
+
+ assert len([comp for comp in sfg.components if isinstance(comp, Delay)]) == 2
+
def test_direct_form_fir():
impulse_response = [0.3, 0.5, 0.7]
--
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