-""" Combinatorial Multi-input multiplexer block conforming to Pipeline API
+""" Combinatorial Multi-input and Multi-output multiplexer blocks
+ conforming to Pipeline API
+
+ Multi-input is complex because if any one input is ready, the output
+ can be ready, and the decision comes from a separate module.
+
+ Multi-output is simple (pretty much identical to UnbufferedPipeline),
+ and the selection is just a mux. The only proviso (difference) being:
+ the outputs not being selected have to have their o_ready signals
+ DEASSERTED.
"""
from math import log
def ports(self):
res = []
for i in range(len(self.p)):
- res += [self.p[i].i_valid, self.p[i].o_ready,
- self.p[i].i_data]# XXX need flattening!]
- res += [self.n.i_ready, self.n.o_valid,
- self.n.o_data] # XXX need flattening!]
+ p = self.p[i]
+ res += [p.i_valid, p.o_ready]
+ if hasattr(p.i_data, "ports"):
+ res += p.i_data.ports()
+ else:
+ rres = p.i_data
+ if not isinstance(rres, Sequence):
+ rres = [rres]
+ res += rres
+ n = self.n
+ res += [n.i_ready, n.o_valid]
+ if hasattr(n.o_data, "ports"):
+ res += n.o_data.ports()
+ else:
+ rres = n.o_data
+ if not isinstance(rres, Sequence):
+ rres = [rres]
+ res += rres
return res
-
class MultiOutControlBase:
""" Common functions for Pipeline API
"""
return eq(self.p.i_data, i)
def ports(self):
- res = []
- res += [self.p.i_valid, self.p.o_ready,
- self.p.i_data] # XXX need flattening!
+ res = [self.p.i_valid, self.p.o_ready]
+ if hasattr(self.p.i_data, "ports"):
+ res += self.p.i_data.ports()
+ else:
+ res += self.p.i_data
+
for i in range(len(self.n)):
- res += [self.n[i].i_ready, self.n[i].o_valid,
- self.n[i].o_data] # XXX need flattening!
+ n = self.n[i]
+ res += [n.i_ready, n.o_valid]
+ if hasattr(n.o_data, "ports"):
+ res += n.o_data.ports()
+ else:
+ res += n.o_data
return res
-
class CombMultiOutPipeline(MultiOutControlBase):
""" A multi-input Combinatorial block conforming to the Pipeline API
Attributes:
-----------
- p.i_data : StageInput, shaped according to ispec
- The pipeline input
- p.o_data : StageOutput, shaped according to ospec
- The pipeline output
- r_data : input_shape according to ispec
- A temporary (buffered) copy of a prior (valid) input.
- This is HELD if the output is not ready. It is updated
- SYNCHRONOUSLY.
+ p.i_data : stage input data (non-array). shaped according to ispec
+ n.o_data : stage output data array. shaped according to ospec
"""
def __init__(self, stage, n_len, n_mux):
if hasattr(self.stage, "setup"):
self.stage.setup(m, r_data)
+ # multiplexer id taken from n_mux
mid = self.n_mux.m_id
- data_valid = Signal() # is data valid or not
+ # temporaries
p_i_valid = Signal(reset_less=True)
- m.d.comb += p_i_valid.eq(self.p.i_valid_logic())
+ pv = Signal(reset_less=True)
+ m.d.comb += p_i_valid.eq(self.p.i_valid_test)
+ m.d.comb += pv.eq(self.p.i_valid & self.p.o_ready)
+ # all outputs to next stages first initialised to zero (invalid)
+ # the only output "active" is then selected by the muxid
for i in range(len(self.n)):
m.d.comb += self.n[i].o_valid.eq(0)
data_valid = self.n[mid].o_valid
- #m.d.comb += self.n[mid].o_valid.eq(data_valid)
m.d.comb += self.p.o_ready.eq(~data_valid | self.n[mid].i_ready)
m.d.comb += data_valid.eq(p_i_valid | \
(~self.n[mid].i_ready & data_valid))
- with m.If(self.p.i_valid & self.p.o_ready):
+ with m.If(pv):
m.d.comb += eq(r_data, self.p.i_data)
m.d.comb += eq(self.n[mid].o_data, self.stage.process(r_data))
n_i_readyn = Array(n_i_readyn)
data_valid = Array(data_valid)
+ nirn = Signal(reset_less=True)
+ m.d.comb += nirn.eq(~self.n.i_ready)
mid = self.p_mux.m_id
for i in range(p_len):
m.d.comb += data_valid[i].eq(0)
m.d.comb += self.p[i].o_ready.eq(0)
m.d.comb += p_i_valid[mid].eq(self.p_mux.active)
m.d.comb += self.p[mid].o_ready.eq(~data_valid[mid] | self.n.i_ready)
- m.d.comb += n_i_readyn[mid].eq(~self.n.i_ready & data_valid[mid])
+ m.d.comb += n_i_readyn[mid].eq(nirn & data_valid[mid])
anyvalid = Signal(i, reset_less=True)
av = []
for i in range(p_len):
return m
+class CombMuxOutPipe(CombMultiOutPipeline):
+ def __init__(self, stage, n_len):
+ # HACK: stage is also the n-way multiplexer
+ CombMultiOutPipeline.__init__(self, stage, n_len=n_len, n_mux=stage)
+
+ # HACK: n-mux is also the stage... so set the muxid equal to input mid
+ stage.m_id = self.p.i_data.mid
+
+
+
class InputPriorityArbiter:
+ """ arbitration module for Input-Mux pipe, baed on PriorityEncoder
+ """
def __init__(self, pipe, num_rows):
self.pipe = pipe
self.num_rows = num_rows
in_ready = []
for i in range(self.num_rows):
p_i_valid = Signal(reset_less=True)
- m.d.comb += p_i_valid.eq(self.pipe.p[i].i_valid_logic())
+ m.d.comb += p_i_valid.eq(self.pipe.p[i].i_valid_test)
in_ready.append(p_i_valid)
m.d.comb += pe.i.eq(Cat(*in_ready)) # array of input "valids"
m.d.comb += self.active.eq(~pe.n) # encoder active (one input valid)
-class ExamplePipeline(CombMultiInPipeline):
+class PriorityCombMuxInPipe(CombMultiInPipeline):
""" an example of how to use the combinatorial pipeline.
"""
- def __init__(self, p_len=2):
+ def __init__(self, stage, p_len=2):
p_mux = InputPriorityArbiter(self, p_len)
- CombMultiInPipeline.__init__(self, ExampleStage, p_len, p_mux)
+ CombMultiInPipeline.__init__(self, stage, p_len, p_mux)
if __name__ == '__main__':
- dut = ExamplePipeline()
+ dut = PriorityCombMuxInPipe(ExampleStage)
vl = rtlil.convert(dut, ports=dut.ports())
with open("test_combpipe.il", "w") as f:
f.write(vl)