litex/migen/genlib/rob.py

79 lines
2.4 KiB
Python

from migen.fhdl.std import *
class ReorderSlot:
def __init__(self, tag_width, data_width):
self.wait_data = Signal()
self.has_data = Signal()
self.tag = Signal(tag_width)
self.data = Signal(data_width)
class ReorderBuffer(Module):
def __init__(self, tag_width, data_width, depth):
# issue
self.can_issue = Signal()
self.issue = Signal()
self.tag_issue = Signal(tag_width)
# call
self.call = Signal()
self.tag_call = Signal(tag_width)
self.data_call = Signal(data_width)
# readback
self.can_read = Signal()
self.read = Signal()
self.data_read = Signal(data_width)
###
empty_count = Signal(max=depth+1, reset=depth)
produce = Signal(max=depth)
consume = Signal(max=depth)
slots = Array(ReorderSlot(tag_width, data_width)
for n in range(depth))
# issue
self.comb += self.can_issue.eq(empty_count != 0)
self.sync += If(self.issue & self.can_issue,
empty_count.eq(empty_count - 1),
If(produce == depth - 1,
produce.eq(0)
).Else(
produce.eq(produce + 1)
),
slots[produce].wait_data.eq(1),
slots[produce].tag.eq(self.tag_issue)
)
# call
for n, slot in enumerate(slots):
self.sync += If(self.call & slot.wait_data & (self.tag_call == slot.tag),
slot.wait_data.eq(0),
slot.has_data.eq(1),
slot.data.eq(self.data_call)
)
# readback
self.comb += [
self.can_read.eq(slots[consume].has_data),
self.data_read.eq(slots[consume].data)
]
self.sync += [
If(self.read & self.can_read,
empty_count.eq(empty_count + 1),
If(consume == depth - 1,
consume.eq(0)
).Else(
consume.eq(consume + 1)
),
slots[consume].has_data.eq(0)
)
]
# do not touch empty count when issuing and reading at the same time
self.sync += If(self.issue & self.can_issue & self.read & self.can_read,
empty_count.eq(empty_count)
)