167 lines
4.0 KiB
Python
167 lines
4.0 KiB
Python
from migen.fhdl.structure import *
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from migen.corelogic.misc import optree
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class FinalizeError(Exception):
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pass
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(SLOT_EMPTY, SLOT_PENDING, SLOT_PROCESSING) = range(3)
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class Slot:
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def __init__(self, aw, time):
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self.state = Signal(BV(2))
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self.we = Signal()
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self.adr = Signal(BV(aw))
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self.time = time
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if self.time:
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self._counter = Signal(BV(bits_for(time)))
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self.mature = Signal()
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self.allocate = Signal()
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self.allocate_we = Signal()
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self.allocate_adr = Signal(BV(aw))
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self.process = Signal()
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self.call = Signal()
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def get_fragment(self):
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comb = []
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sync = [
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If(self.allocate,
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self.state.eq(SLOT_PENDING),
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self.we.eq(self.allocate_we),
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self.adr.eq(self.allocate_adr)
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),
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If(self.process, self.state.eq(SLOT_PROCESSING)),
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If(self.call, self.state.eq(SLOT_EMPTY))
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]
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if self.time:
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comb += [
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self.mature.eq(self._counter == 0)
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]
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sync += [
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If(self.allocate,
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self._counter.eq(self.time)
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).Elif(self._counter != 0,
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self._counter.eq(self._counter - 1)
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)
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]
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return Fragment(comb, sync)
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class Port:
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def __init__(self, hub, nslots):
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self.hub = hub
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self.slots = [Slot(self.hub.aw, self.hub.time) for i in range(nslots)]
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self.finalized = False
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# request issuance
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self.adr = Signal(BV(self.hub.aw))
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self.we = Signal()
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self.stb = Signal()
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# tag_issue is created by finalize()
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self.ack = Signal()
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# request completion
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self.call = Signal()
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# tag_call is created by finalize()
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self.dat_r = Signal(BV(self.hub.dw))
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self.dat_w = Signal(BV(self.hub.dw))
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self.dat_wm = Signal(BV(self.hub.dw//8))
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def finalize(self, tagbits, base):
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if self.finalized:
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raise FinalizeError
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self.finalized = True
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self.tagbits = tagbits
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self.base = base
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nslots = len(self.slots)
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if nslots > 1:
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self.tag_issue = Signal(BV(bits_for(nslots-1)))
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self.tag_call = Signal(BV(tagbits))
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def get_call_expression(self, slotn=0):
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if not self.finalized:
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raise FinalizeError
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return self.call \
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& (self.tag_call == Constant(self.base + slotn, BV(self.tagbits)))
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def get_fragment(self):
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if not self.finalized:
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raise FinalizeError
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slots_fragment = sum([s.get_fragment() for s in self.slots], Fragment())
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comb = []
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sync = []
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# allocate
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for s in self.slots:
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comb += [
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s.allocate_we.eq(self.we),
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s.allocate_adr.eq(self.adr)
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]
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choose_slot = None
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for s in reversed(self.slots):
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choose_slot = If(s.state == SLOT_EMPTY,
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self.ack.eq(1),
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s.allocate.eq(self.stb)
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).Else(choose_slot)
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comb.append(choose_slot)
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# call
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comb += [s.call.eq(self.get_call_expression(n))
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for n, s in enumerate(self.slots)]
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return slots_fragment + Fragment(comb, sync)
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class Hub:
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def __init__(self, aw, dw, time=0):
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self.aw = aw
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self.dw = dw
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self.time = time
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self.ports = []
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self.finalized = False
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self.call = Signal()
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# tag_call is created by finalize()
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self.dat_r = Signal(BV(self.dw))
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self.dat_w = Signal(BV(self.dw))
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self.dat_wm = Signal(BV(self.dw//8))
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def get_port(self, nslots=1):
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if self.finalized:
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raise FinalizeError
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new_port = Port(self, nslots)
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self.ports.append(new_port)
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return new_port
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def finalize(self):
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if self.finalized:
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raise FinalizeError
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self.finalized = True
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nslots = sum([len(port.slots) for port in self.ports])
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tagbits = bits_for(nslots-1)
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base = 0
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for port in self.ports:
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port.finalize(tagbits, base)
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base += len(port.slots)
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self.tag_call = Signal(BV(tagbits))
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def get_slots(self):
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return sum([port.slots for port in self.ports], [])
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def get_fragment(self):
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if not self.finalized:
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raise FinalizeError
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ports = sum([port.get_fragment() for port in self.ports], Fragment())
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comb = []
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for port in self.ports:
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comb += [
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port.call.eq(self.call),
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port.tag_call.eq(self.tag_call),
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port.dat_r.eq(self.dat_r)
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]
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comb += [
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self.dat_w.eq(optree("|", [port.dat_w for port in self.ports])),
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self.dat_wm.eq(optree("|", [port.dat_wm for port in self.ports]))
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]
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return ports + Fragment(comb)
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