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dsp.fir: actively cull zero delays

This commit is contained in:
Robert Jördens 2017-06-29 11:24:56 +02:00
parent f520d4a768
commit 32a33500c8
1 changed files with 12 additions and 7 deletions
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19
artiq/gateware/dsp/fir.py
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@ -63,7 +63,7 @@ class ParallelFIR(Module):
:param arch: architecture (default: "DSP48E1"). :param arch: architecture (default: "DSP48E1").
""" """
def __init__(self, coefficients, parallelism, width=16, def __init__(self, coefficients, parallelism, width=16,
arch="DSP48E1"): arch="DSP48E1", cull_delays=()):
self.width = width self.width = width
self.parallelism = p = parallelism self.parallelism = p = parallelism
n = len(coefficients) n = len(coefficients)
@ -95,6 +95,7 @@ class ParallelFIR(Module):
o = Signal((w.P, True), reset_less=True) o = Signal((w.P, True), reset_less=True)
self.comb += self.o[delay].eq(o >> c_shift) self.comb += self.o[delay].eq(o >> c_shift)
# Make products # Make products
tap = delay
for i, c in enumerate(cs): for i, c in enumerate(cs):
# simplify for halfband and symmetric filters # simplify for halfband and symmetric filters
if not c or c in cs[:i]: if not c or c in cs[:i]:
@ -103,16 +104,19 @@ class ParallelFIR(Module):
m = Signal.like(o) m = Signal.like(o)
o0, o = o, Signal.like(o) o0, o = o, Signal.like(o)
q = Signal.like(x[0]) q = Signal.like(x[0])
if delay + p <= js[0]: if tap + p <= js[0]:
self.sync += o0.eq(o + m) self.sync += o0.eq(o + m)
delay += p tap += p
else: else:
self.comb += o0.eq(o + m) self.comb += o0.eq(o + m)
assert js[0] - delay >= 0 assert min(js) - tap >= 0
self.comb += q.eq(reduce(add, [x[j - delay] for j in js])) js = [j for j in js if (p - 1 - j - tap) % p not in cull_delays]
if not js:
continue
self.comb += q.eq(reduce(add, [x[j - tap] for j in js]))
self.sync += m.eq(c*q) self.sync += m.eq(c*q)
# symmetric rounding # symmetric rounding
if c_shift > 1: if c_shift > 1 and delay not in cull_delays:
self.comb += o.eq((1 << c_shift - 1) - 1) self.comb += o.eq((1 << c_shift - 1) - 1)
@ -157,7 +161,8 @@ class ParallelHBFUpsampler(Module):
i = [self.i] i = [self.i]
for coeff in coefficients: for coeff in coefficients:
self.parallelism *= 2 self.parallelism *= 2
hbf = ParallelFIR(coeff, self.parallelism, width, **kwargs) hbf = ParallelFIR(coeff, self.parallelism, width=width,
cull_delays={0}, **kwargs)
self.submodules += hbf self.submodules += hbf
self.comb += [a.eq(b) for a, b in zip(hbf.i[1::2], i)] self.comb += [a.eq(b) for a, b in zip(hbf.i[1::2], i)]
i = hbf.o i = hbf.o