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core/multiplexer: synchronize ready on tXXDController and tFAWcontroller to improve timings

This commit is contained in:
Florent Kermarrec 2018-08-14 15:13:10 +02:00
parent 147466beec
commit c1b1b07b3c
1 changed files with 28 additions and 17 deletions
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45
litedram/core/multiplexer.py
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@ -1,5 +1,5 @@
from functools import reduce from functools import reduce
from operator import or_, and_ from operator import add, or_, and_
from migen import * from migen import *
from migen.genlib.roundrobin import * from migen.genlib.roundrobin import *
@ -118,38 +118,49 @@ class _Steerer(Module):
class tXXDController(Module): class tXXDController(Module):
def __init__(self, txxd): def __init__(self, txxd):
self.valid = Signal() self.valid = valid = Signal()
self.ready = Signal(reset=1) self.ready = ready = Signal(reset=1)
ready.attr.add("no_retiming")
# # # # # #
if txxd is not None: if txxd is not None:
count = Signal(max=txxd+1) count = Signal(max=txxd + 1)
self.sync += \ self.sync += \
If(self.valid, If(valid,
count.eq(txxd-1) count.eq(txxd - 1),
).Elif(~self.ready, If((txxd - 1) == 0,
count.eq(count-1) ready.eq(1)
).Else(
ready.eq(0)
)
).Elif(~ready,
count.eq(count - 1),
If(count == 1, ready.eq(1))
) )
self.comb += self.ready.eq(count == 0)
class tFAWController(Module): class tFAWController(Module):
def __init__(self, tfaw): def __init__(self, tfaw):
self.valid = Signal() self.valid = valid = Signal()
self.ready = Signal(reset=1) self.ready = ready = Signal(reset=1)
ready.attr.add("no_retiming")
# # # # # #
if tfaw is not None: if tfaw is not None:
count = Signal(max=tfaw) count = Signal(max=tfaw)
window = Signal(tfaw) window = Signal(tfaw)
self.sync += window.eq(Cat(self.valid, window)) self.sync += window.eq(Cat(valid, window))
for i in range(tfaw): self.comb += reduce(add, [window[i] for i in range(tfaw)])
next_count = Signal(max=tfaw) self.sync += \
self.comb += next_count.eq(count + window[i]) If(count < 4,
count = next_count If(count == 3,
self.comb += If(count >= 4, self.ready.eq(0)) ready.eq(~valid)
).Else(
ready.eq(1)
)
)
class Multiplexer(Module, AutoCSR): class Multiplexer(Module, AutoCSR):