44 lines
1.6 KiB
Python
44 lines
1.6 KiB
Python
from math import log2
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from migen import *
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from litedram.frontend.dma import LiteDRAMDMAReader;
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# LiteDRAMDFBMAReader --------------------------------------------------------------------------------
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# Hardwire the loop, uses control signals instead of CSRs
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class LiteDRAMFBDMAReader(LiteDRAMDMAReader):
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def __init__(self, port, fifo_depth=16, default_base=0, default_length=0):
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LiteDRAMDMAReader.__init__(self = self, port = port, fifo_depth = fifo_depth, fifo_buffered = True, with_csr = False)
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self.enable = Signal(reset = 0)
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self.base = Signal(32, reset = default_base)
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self.length = Signal(32, reset = default_length)
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shift = log2_int(self.port.data_width//8)
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base = Signal(self.port.address_width)
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length = Signal(self.port.address_width)
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offset = Signal(self.port.address_width, reset = 0)
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self.comb += base.eq(self.base[shift:])
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self.comb += length.eq(self.length[shift:])
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fsm = FSM(reset_state="IDLE")
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fsm = ResetInserter()(fsm)
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self.submodules.fsm = fsm
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self.comb += fsm.reset.eq(~self.enable)
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fsm.act("IDLE",
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NextValue(offset, 0),
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NextState("RUN"),
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)
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fsm.act("RUN",
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self.sink.valid.eq(1),
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self.sink.last.eq(offset == (length - 1)),
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self.sink.address.eq(base + offset),
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If(self.sink.ready,
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NextValue(offset, offset + 1),
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If(self.sink.last,
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NextValue(offset, 0)
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)
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)
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)
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