71 lines
1.8 KiB
Python
71 lines
1.8 KiB
Python
from migen.fhdl.std import *
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from migen.fhdl import verilog
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class BitonicSort(Module):
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"""Combinatorial sorting network
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The Bitonic sort is implemented as a combinatorial sort using
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comparators and multiplexers. Its asymptotic complexity (in terms of
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number of comparators/muxes) is O(n log(n)**2), like mergesort or
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shellsort.
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http://www.dps.uibk.ac.at/~cosenza/teaching/gpu/sort-batcher.pdf
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http://www.inf.fh-flensburg.de/lang/algorithmen/sortieren/bitonic/bitonicen.htm
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http://www.myhdl.org/doku.php/cookbook:bitonic
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Parameters
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----------
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n : int
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Number of inputs and output signals.
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m : int
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Bit width of inputs and outputs. Or a tuple of `(m, signed)`.
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ascending : bool
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Sort direction. `True` if input is to be sorted ascending,
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`False` for descending. Defaults to ascending.
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Attributes
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----------
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i : list of Signals, in
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Input values, each `m` wide.
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o : list of Signals, out
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Output values, sorted, each `m` bits wide.
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"""
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def __init__(self, n, m, ascending=True):
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self.i = [Signal(m) for i in range(n)]
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self.o = [Signal(m) for i in range(n)]
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self._sort(self.i, self.o, int(ascending), m)
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def _sort_two(self, i0, i1, o0, o1, dir):
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self.comb += [
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o0.eq(i0),
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o1.eq(i1),
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If(dir == (i0 > i1),
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o0.eq(i1),
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o1.eq(i0),
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)]
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def _merge(self, i, o, dir, m):
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n = len(i)
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k = n//2
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if n > 1:
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t = [Signal(m) for j in range(n)]
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for j in range(k):
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self._sort_two(i[j], i[j + k], t[j], t[j + k], dir)
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self._merge(t[:k], o[:k], dir, m)
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self._merge(t[k:], o[k:], dir, m)
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else:
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self.comb += o[0].eq(i[0])
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def _sort(self, i, o, dir, m):
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n = len(i)
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k = n//2
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if n > 1:
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t = [Signal(m) for j in range(n)]
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self._sort(i[:k], t[:k], 1, m) # ascending
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self._sort(i[k:], t[k:], 0, m) # descending
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self._merge(t, o, dir, m)
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else:
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self.comb += o[0].eq(i[0])
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