where data will flow on *every* clock when the conditions are right.
input acceptance conditions are when:
- * incoming previous-stage strobe (i.p_valid) is HIGH
- * outgoing previous-stage ready (o.p_ready) is LOW
+ * incoming previous-stage strobe (p.i_valid) is HIGH
+ * outgoing previous-stage ready (p.o_ready) is LOW
output transmission conditions are when:
- * outgoing next-stage strobe (o.n_valid) is HIGH
- * outgoing next-stage ready (i.n_ready) is LOW
+ * outgoing next-stage strobe (n.o_valid) is HIGH
+ * outgoing next-stage ready (n.i_ready) is LOW
the tricky bit is when the input has valid data and the output is not
ready to accept it. if it wasn't for the clock synchronisation, it
from collections.abc import Sequence
-class IOAckIn:
+class PrevControl:
+ """ contains signals that come *from* the previous stage (both in and out)
+ * i_valid: input from previous stage indicating incoming data is valid
+ * o_ready: output to next stage indicating readiness to accept data
+ * i_data : an input - added by the user of this class
+ """
def __init__(self):
- self.p_valid = Signal() # >>in - comes in from PREVIOUS stage
- self.n_ready = Signal() # in<< - comes in from the NEXT stage
+ self.i_valid = Signal(name="p_i_valid") # >>in
+ self.o_ready = Signal(name="p_o_ready") # <<out
+ def connect_in(self, prev):
+ """ helper function to connect stage to an input source. do not
+ use to connect stage-to-stage!
+ """
+ return [self.i_valid.eq(prev.i_valid),
+ prev.o_ready.eq(self.o_ready),
+ eq(self.i_data, prev.i_data),
+ ]
-class IOAckOut:
+class NextControl:
+ """ contains the signals that go *to* the next stage (both in and out)
+ * o_valid: output indicating to next stage that data is valid
+ * i_ready: input from next stage indicating that it can accept data
+ * o_data : an output - added by the user of this class
+ """
def __init__(self):
- self.n_valid = Signal() # out>> - goes out to the NEXT stage
- self.p_ready = Signal() # <<out - goes out to the PREVIOUS stage
+ self.o_valid = Signal(name="n_o_valid") # out>>
+ self.i_ready = Signal(name="n_i_ready") # <<in
+
+ def connect_to_next(self, nxt):
+ """ helper function to connect to the next stage data/valid/ready.
+ data/valid is passed *TO* nxt, and ready comes *IN* from nxt.
+ """
+ return [nxt.i_valid.eq(self.o_valid),
+ self.i_ready.eq(nxt.o_ready),
+ eq(nxt.i_data, self.o_data),
+ ]
+
+ def connect_out(self, nxt):
+ """ helper function to connect stage to an output source. do not
+ use to connect stage-to-stage!
+ """
+ return [nxt.o_valid.eq(self.o_valid),
+ self.i_ready.eq(nxt.i_ready),
+ eq(nxt.o_data, self.o_data),
+ ]
def eq(o, i):
if ever the input is ready and the output is not, processed data
is stored in a temporary register.
- stage-1 i.p_valid >>in stage o.n_valid out>> stage+1
- stage-1 o.p_ready <<out stage i.n_ready <<in stage+1
- stage-1 i.data >>in stage o.data out>> stage+1
+ stage-1 p.i_valid >>in stage n.o_valid out>> stage+1
+ stage-1 p.o_ready <<out stage n.i_ready <<in stage+1
+ stage-1 p.i_data >>in stage n.o_data out>> stage+1
| |
process --->----^
| |
+-- r_data ->-+
- input data i_data is read (only), is processed and goes into an
+ input data p.i_data is read (only), is processed and goes into an
intermediate result store [process()]. this is updated combinatorially.
in a non-stall condition, the intermediate result will go into the
* ispec: returns output signals to the output specification
* process: takes an input instance and returns processed data
- i_data -> process() -> result --> o.data
- | ^
- | |
- +-> r_data -+
+ p.i_data -> process() -> result --> n.o_data
+ | ^
+ | |
+ +-> r_data -+
"""
- # input: strobe comes in from previous stage, ready comes in from next
- self.i = IOAckIn()
- #self.i.p_valid = Signal() # >>in - comes in from PREVIOUS stage
- #self.i.n_ready = Signal() # in<< - comes in from the NEXT stage
+ self.stage = stage
- # output: strobe goes out to next stage, ready comes in from previous
- self.o = IOAckOut()
- #self.o.n_valid = Signal() # out>> - goes out to the NEXT stage
- #self.o.p_ready = Signal() # <<out - goes out to the PREVIOUS stage
+ # set up input and output IO ACK (prev/next ready/valid)
+ self.p = PrevControl()
+ self.n = NextControl()
# set up the input and output data
- self.i.data = stage.ispec() # input type
- self.r_data = stage.ospec() # all these are output type
- self.result = stage.ospec()
- self.o.data = stage.ospec()
- self.stage = stage
+ self.p.i_data = stage.ispec() # input type
+ self.r_data = stage.ospec() # all these are output type
+ self.result = stage.ospec()
+ self.n.o_data = stage.ospec()
- def connect_next(self, nxt):
- """ helper function to connect the next stage data/valid/ready
+ def connect_to_next(self, nxt):
+ """ helper function to connect to the next stage data/valid/ready.
"""
- return [nxt.i.p_valid.eq(self.o.n_valid),
- self.i.n_ready.eq(nxt.o.p_ready),
- eq(nxt.i.data, self.o.data),
- ]
+ return self.n.connect_to_next(nxt.p)
def connect_in(self, prev):
""" helper function to connect stage to an input source. do not
use to connect stage-to-stage!
"""
- return [self.i.p_valid.eq(prev.i.p_valid),
- prev.o.p_ready.eq(self.o.p_ready),
- eq(self.i.data, prev.i.data),
- ]
+ return self.p.connect_in(prev.p)
def connect_out(self, nxt):
""" helper function to connect stage to an output source. do not
use to connect stage-to-stage!
"""
- return [nxt.o.n_valid.eq(self.o.n_valid),
- self.i.n_ready.eq(nxt.i.n_ready),
- eq(nxt.o.data, self.o.data),
- ]
+ return self.n.connect_out(nxt.n)
def set_input(self, i):
""" helper function to set the input data
"""
- return eq(self.i.data, i)
+ return eq(self.p.i_data, i)
def update_buffer(self):
""" copies the result into the intermediate register r_data,
def update_output(self):
""" copies the (combinatorial) result into the output
"""
- return eq(self.o.data, self.result)
+ return eq(self.n.o_data, self.result)
def flush_buffer(self):
""" copies the *intermediate* register r_data into the output
"""
- return eq(self.o.data, self.r_data)
+ return eq(self.n.o_data, self.r_data)
def ports(self):
- return [self.i.data, self.o.data]
+ return [self.p.i_data, self.n.o_data]
def elaborate(self, platform):
m = Module()
+ if hasattr(self.stage, "setup"):
+ self.stage.setup(m, self.p.i_data)
# establish some combinatorial temporaries
o_n_validn = Signal(reset_less=True)
i_p_valid_o_p_ready = Signal(reset_less=True)
- m.d.comb += [o_n_validn.eq(~self.o.n_valid),
- i_p_valid_o_p_ready.eq(self.i.p_valid & self.o.p_ready),
+ m.d.comb += [o_n_validn.eq(~self.n.o_valid),
+ i_p_valid_o_p_ready.eq(self.p.i_valid & self.p.o_ready),
]
# store result of processing in combinatorial temporary
- with m.If(self.i.p_valid): # input is valid: process it
- m.d.comb += eq(self.result, self.stage.process(self.i.data))
+ with m.If(self.p.i_valid): # input is valid: process it
+ m.d.comb += eq(self.result, self.stage.process(self.p.i_data))
# if not in stall condition, update the temporary register
- with m.If(self.o.p_ready): # not stalled
+ with m.If(self.p.o_ready): # not stalled
m.d.sync += self.update_buffer()
- #with m.If(self.i.p_rst): # reset
- # m.d.sync += self.o.n_valid.eq(0)
- # m.d.sync += self.o.p_ready.eq(0)
- with m.If(self.i.n_ready): # next stage is ready
- with m.If(self.o.p_ready): # not stalled
+ #with m.If(self.p.i_rst): # reset
+ # m.d.sync += self.n.o_valid.eq(0)
+ # m.d.sync += self.p.o_ready.eq(0)
+ with m.If(self.n.i_ready): # next stage is ready
+ with m.If(self.p.o_ready): # not stalled
# nothing in buffer: send (processed) input direct to output
- m.d.sync += [self.o.n_valid.eq(self.i.p_valid),
+ m.d.sync += [self.n.o_valid.eq(self.p.i_valid),
self.update_output(),
]
- with m.Else(): # o.p_ready is false, and something is in buffer.
+ with m.Else(): # p.o_ready is false, and something is in buffer.
# Flush the [already processed] buffer to the output port.
- m.d.sync += [self.o.n_valid.eq(1),
+ m.d.sync += [self.n.o_valid.eq(1),
self.flush_buffer(),
# clear stall condition, declare register empty.
- self.o.p_ready.eq(1),
+ self.p.o_ready.eq(1),
]
- # ignore input, since o.p_ready is also false.
+ # ignore input, since p.o_ready is also false.
- # (i.n_ready) is false here: next stage is ready
+ # (n.i_ready) is false here: next stage is ready
with m.Elif(o_n_validn): # next stage being told "ready"
- m.d.sync += [self.o.n_valid.eq(self.i.p_valid),
- self.o.p_ready.eq(1), # Keep the buffer empty
+ m.d.sync += [self.n.o_valid.eq(self.p.i_valid),
+ self.p.o_ready.eq(1), # Keep the buffer empty
# set the output data (from comb result)
self.update_output(),
]
- # (i.n_ready) false and (o.n_valid) true:
+ # (n.i_ready) false and (n.o_valid) true:
with m.Elif(i_p_valid_o_p_ready):
# If next stage *is* ready, and not stalled yet, accept input
- m.d.sync += self.o.p_ready.eq(~(self.i.p_valid & self.o.n_valid))
+ m.d.sync += self.p.o_ready.eq(~(self.p.i_valid & self.n.o_valid))
return m
def ports(self):
- return [self.i.p_valid, self.i.n_ready,
- self.o.n_valid, self.o.p_ready,
+ return [self.p.i_valid, self.n.i_ready,
+ self.n.o_valid, self.p.o_ready,
]
BufferedPipeline.__init__(self, ExampleStage)
+class CombPipe:
+ """A simple pipeline stage containing combinational logic that can execute
+ completely in one clock cycle.
+
+ Parameters:
+ -----------
+ input_shape : int or tuple or None
+ the shape of ``input.data`` and ``comb_input``
+ output_shape : int or tuple or None
+ the shape of ``output.data`` and ``comb_output``
+ name : str
+ the name
+
+ Attributes:
+ -----------
+ input : StageInput
+ The pipeline input
+ output : StageOutput
+ The pipeline output
+ comb_input : Signal, input_shape
+ The input to the combinatorial logic
+ comb_output: Signal, output_shape
+ The output of the combinatorial logic
+ """
+
+ def __init__(self, stage):
+ self.stage = stage
+ self._data_valid = Signal()
+ # set up input and output IO ACK (prev/next ready/valid)
+ self.p = PrevControl()
+ self.n = NextControl()
+
+ # set up the input and output data
+ self.p.i_data = stage.ispec() # input type
+ self.r_data = stage.ispec() # input type
+ self.result = stage.ospec() # output data
+ self.n.o_data = stage.ospec() # output type
+ self.n.o_data.name = "outdata"
+
+ def set_input(self, i):
+ """ helper function to set the input data
+ """
+ return eq(self.p.i_data, i)
+
+ def elaborate(self, platform):
+ m = Module()
+ if hasattr(self.stage, "setup"):
+ self.stage.setup(m, self.r_data)
+ m.d.comb += eq(self.result, self.stage.process(self.r_data))
+ m.d.comb += self.n.o_valid.eq(self._data_valid)
+ m.d.comb += self.p.o_ready.eq(~self._data_valid | self.n.i_ready)
+ m.d.sync += self._data_valid.eq(self.p.i_valid | \
+ (~self.n.i_ready & self._data_valid))
+ with m.If(self.p.i_valid & self.p.o_ready):
+ m.d.sync += eq(self.r_data, self.p.i_data)
+ m.d.comb += eq(self.n.o_data, self.result)
+ return m
+
+ def ports(self):
+ return [self.p.i_data, self.n.o_data]
+
+
+class ExampleCombPipe(CombPipe):
+ """ an example of how to use the combinatorial pipeline.
+ """
+
+ def __init__(self):
+ CombPipe.__init__(self, ExampleStage)
+
+
if __name__ == '__main__':
dut = ExampleBufPipe()
vl = rtlil.convert(dut, ports=dut.ports())
with open("test_bufpipe.il", "w") as f:
f.write(vl)
+
+ dut = ExampleCombPipe()
+ vl = rtlil.convert(dut, ports=dut.ports())
+ with open("test_combpipe.il", "w") as f:
+ f.write(vl)
projects / ieee754fpu.git / blobdiff