migen/actorlib: add packet.py to manage dataflow packets (Arbiter, Dispatcher, Header definitions, Buffer)

migen/actorlib/packet.py

@@ -0,0 +1,201 @@
+from migen.fhdl.std import *
+from migen.genlib.roundrobin import *
+from migen.genlib.record import *
+from migen.flow.actor import *
+from migen.actorlib.fifo import SyncFIFO
+from migen.genlib.fsm import FSM, NextState
+from migen.genlib.misc import reverse_bytes
+
+
+class Status(Module):
+    def __init__(self, endpoint):
+        self.sop = sop = Signal()
+        self.eop = eop =Signal()
+        self.ongoing = Signal()
+
+        ongoing = Signal()
+        self.comb += \
+            If(endpoint.stb,
+                sop.eq(endpoint.sop),
+                eop.eq(endpoint.eop & endpoint.ack)
+            )
+        self.sync += ongoing.eq((sop | ongoing) & ~eop)
+        self.comb += self.ongoing.eq((sop | ongoing) & ~eop)
+
+
+class Arbiter(Module):
+    def __init__(self, masters, slave):
+        if len(masters) == 0:
+            pass
+        elif len(masters) == 1:
+            self.grant = Signal()
+            self.comb += Record.connect(masters.pop(), slave)
+        else:
+            self.submodules.rr = RoundRobin(len(masters))
+            self.grant = self.rr.grant
+            cases = {}
+            for i, master in enumerate(masters):
+                status = Status(master)
+                self.submodules += status
+                self.comb += self.rr.request[i].eq(status.ongoing)
+                cases[i] = [Record.connect(master, slave)]
+            self.comb += Case(self.grant, cases)
+
+
+class Dispatcher(Module):
+    def __init__(self, master, slaves, one_hot=False):
+        if len(slaves) == 0:
+            self.sel = Signal()
+        elif len(slaves) == 1:
+            self.comb += Record.connect(master, slaves.pop())
+            self.sel = Signal()
+        else:
+            if one_hot:
+                self.sel = Signal(len(slaves))
+            else:
+                self.sel = Signal(max=len(slaves))
+
+            # # #
+
+            status = Status(master)
+            self.submodules += status
+
+            sel = Signal.like(self.sel)
+            sel_ongoing = Signal.like(self.sel)
+            self.sync += \
+                If(status.sop,
+                    sel_ongoing.eq(self.sel)
+                )
+            self.comb += \
+                If(status.sop,
+                    sel.eq(self.sel)
+                ).Else(
+                    sel.eq(sel_ongoing)
+                )
+            cases = {}
+            for i, slave in enumerate(slaves):
+                if one_hot:
+                    idx = 2**i
+                else:
+                    idx = i
+                cases[idx] = [Record.connect(master, slave)]
+            cases["default"] = [master.ack.eq(1)]
+            self.comb += Case(sel, cases)
+
+
+class HeaderField:
+    def __init__(self, byte, offset, width):
+        self.byte = byte
+        self.offset = offset
+        self.width = width
+
+
+class Header:
+    def __init__(self, fields, length, swap_field_bytes=True):
+        self.fields = fields
+        self.length = length
+        self.swap_field_bytes = swap_field_bytes
+
+    def get_layout(self):
+        layout = []
+        for k, v in sorted(self.fields.items()):
+            layout.append((k, v.width))
+        return layout
+
+    def get_field(self, obj, name, width):
+        if "_lsb" in name:
+            field = getattr(obj, name.replace("_lsb", ""))[:width]
+        elif "_msb" in name:
+            field = getattr(obj, name.replace("_msb", ""))[width:2*width]
+        else:
+            field = getattr(obj, name)
+        return field
+
+    def encode(self, obj, signal):
+        r = []
+        for k, v in sorted(self.fields.items()):
+            start = v.byte*8+v.offset
+            end = start+v.width
+            field = self.get_field(obj, k, v.width)
+            if self.swap_field_bytes:
+                field = reverse_bytes(field)
+            r.append(signal[start:end].eq(field))
+        return r
+
+    def decode(self, signal, obj):
+        r = []
+        for k, v in sorted(self.fields.items()):
+            start = v.byte*8+v.offset
+            end = start+v.width
+            field = self.get_field(obj, k, v.width)
+            if self.swap_field_bytes:
+                r.append(field.eq(reverse_bytes(signal[start:end])))
+            else:
+                r.append(field.eq(signal[start:end]))
+        return r
+
+
+class Buffer(Module):
+    def __init__(self, description, data_depth, cmd_depth=4, almost_full=None):
+        self.sink = sink = Sink(description)
+        self.source = source = Source(description)
+
+        # # #
+
+        sink_status = Status(self.sink)
+        source_status = Status(self.source)
+        self.submodules += sink_status, source_status
+
+        # store incoming packets
+        # cmds
+        def cmd_description():
+            layout = [("error", 1)]
+            return EndpointDescription(layout)
+        cmd_fifo = SyncFIFO(cmd_description(), cmd_depth)
+        self.submodules += cmd_fifo
+        self.comb += cmd_fifo.sink.stb.eq(sink_status.eop)
+        if hasattr(sink, "error"):
+            self.comb += cmd_fifo.sink.error.eq(sink.error)
+
+        # data
+        data_fifo = SyncFIFO(description, data_depth, buffered=True)
+        self.submodules += data_fifo
+        self.comb += [
+            Record.connect(self.sink, data_fifo.sink),
+            data_fifo.sink.stb.eq(self.sink.stb & cmd_fifo.sink.ack),
+            self.sink.ack.eq(data_fifo.sink.ack & cmd_fifo.sink.ack),
+        ]
+
+        # output packets
+        self.fsm = fsm = FSM(reset_state="IDLE")
+        self.submodules += fsm
+        fsm.act("IDLE",
+            If(cmd_fifo.source.stb,
+                NextState("SEEK_SOP")
+            )
+        )
+        fsm.act("SEEK_SOP",
+            If(~data_fifo.source.sop,
+                data_fifo.source.ack.eq(1)
+            ).Else(
+                NextState("OUTPUT")
+            )
+        )
+        if hasattr(source, "error"):
+            source_error = self.source.error
+        else:
+            source_error = Signal()
+
+        fsm.act("OUTPUT",
+            Record.connect(data_fifo.source, self.source),
+            source_error.eq(cmd_fifo.source.error),
+            If(source_status.eop,
+                cmd_fifo.source.ack.eq(1),
+                NextState("IDLE")
+            )
+        )
+
+        # compute almost full
+        if almost_full is not None:
+            self.almost_full = Signal()
+            self.comb += self.almost_full.eq(data_fifo.fifo.level > almost_full)