From: Luke Kenneth Casson Leighton Date: Tue, 5 Apr 2022 10:30:10 +0000 (+0100) Subject: create Ripple module, now joined by RippleMSB X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=d5eb78c004feb45f660e47c34f2aa5203d0475f1;p=nmutil.git create Ripple module, now joined by RippleMSB --- diff --git a/src/nmutil/ripple.py b/src/nmutil/ripple.py index 96a4982..3630995 100644 --- a/src/nmutil/ripple.py +++ b/src/nmutil/ripple.py @@ -17,14 +17,22 @@ from nmigen import Signal, Module, Elaboratable, Mux, Cat from nmigen.cli import main -class RippleLSB(Elaboratable): - """RippleLSB - - based on a partition mask, the LSB is "rippled" (duplicated) - up to the beginning of the next partition. +class Ripple(Elaboratable): + """Ripple + + starting from certain bits (marked by "gates") that bit is "rippled" + up to the point where a gate bit is no longer set. ripple direction can + be set by start_lsb. + + if start_lsb=True: + gates => 1 1 0 0 0 1 1 + (ripples) <<<< xxx <<<<< + results_in => 0 0 1 0 1 0 0 1 + output => 1 1 1 0 0 1 1 1 """ - def __init__(self, width): + def __init__(self, width, start_lsb=True): self.width = width + self.start_lsb = start_lsb self.results_in = Signal(width, reset_less=True) self.gates = Signal(width-1, reset_less=True) self.output = Signal(width, reset_less=True) @@ -34,16 +42,39 @@ class RippleLSB(Elaboratable): comb = m.d.comb width = self.width - current_result = self.results_in[0] - comb += self.output[0].eq(current_result) + results_in = list(self.results_in) + if not self.start_lsb: results_in = reversed(results_in) + l = [results_in[0]] for i in range(width-1): - cur = Mux(self.gates[i], self.results_in[i+1], self.output[i]) - comb += self.output[i+1].eq(cur) + l.append(Mux(self.gates[i], results_in[i+1], self.output[i])) + + if not self.start_lsb: l = reversed(l) + comb += self.output.eq(Cat(*l)) return m +class RippleLSB(Ripple): + """RippleLSB + + based on a partition mask, the LSB is "rippled" (duplicated) + up to the beginning of the next partition. + """ + def __init__(self, width): + Ripple.__init__(self, width, start_lsb=True) + + +class RippleMSB(Ripple): + """RippleMSB + + based on a partition mask, the MSB is "rippled" (duplicated) + down to the beginning of the next partition. + """ + def __init__(self, width): + Ripple.__init__(self, width, start_lsb=True) + + class MoveMSBDown(Elaboratable): """MoveMSBDown