X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;f=src%2Fadd%2Fexample_buf_pipe.py;h=6d13099b93dc549b03598a43cb13cbc876681715;hb=5aa2f167e98633cc1cf2e896d717a132e8d1721b;hp=6d42c1cc6411d7440922bd5f6a6d19c12dff9f41;hpb=e563164de46e525953101317ce5634f7966f4ee2;p=ieee754fpu.git

diff --git a/src/add/example_buf_pipe.py b/src/add/example_buf_pipe.py
index 6d42c1cc..6d13099b 100644
--- a/src/add/example_buf_pipe.py
+++ b/src/add/example_buf_pipe.py
@@ -45,19 +45,32 @@
 
 from nmigen import Signal, Cat, Const, Mux, Module
 from nmigen.cli import verilog, rtlil
+from nmigen.hdl.rec import Record, Layout
+
 from collections.abc import Sequence
 
 
 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
+        * i_valid: previous stage indicating all incoming data is valid.
+                   may be a multi-bit signal, where all bits are required
+                   to be asserted to indicate "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.i_valid = Signal(name="p_i_valid") # >>in
-        self.o_ready = Signal(name="p_o_ready") # <<out
+    def __init__(self, i_width=1):
+        self.i_valid = Signal(i_width, name="p_i_valid") # prev   >>in  self
+        self.o_ready = Signal(name="p_o_ready") # prev   <<out self
+
+    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 NextControl:
@@ -67,8 +80,8 @@ class NextControl:
         * o_data : an output - added by the user of this class
     """
     def __init__(self):
-        self.o_valid = Signal(name="n_o_valid") # out>>
-        self.i_ready = Signal(name="n_i_ready") # <<in
+        self.o_valid = Signal(name="n_o_valid") # self out>>  next
+        self.i_ready = Signal(name="n_i_ready") # self <<in   next
 
     def connect_to_next(self, nxt):
         """ helper function to connect to the next stage data/valid/ready.
@@ -76,73 +89,74 @@ class NextControl:
         """
         return [nxt.i_valid.eq(self.o_valid),
                 self.i_ready.eq(nxt.o_ready),
-                eq(nxt.data, self.data),
+                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):
+    """ makes signals equal: a helper routine which identifies if it is being
+        passsed a list (or tuple) of objects, and calls the objects' eq
+        function.
+
+        complex objects (classes) can be used: they must follow the
+        convention of having an eq member function, which takes the
+        responsibility of further calling eq and returning a list of
+        eq assignments
+
+        Record is a special (unusual, recursive) case, where the input
+        is specified as a dictionary (which may contain further dictionaries,
+        recursively), where the field names of the dictionary must match
+        the Record's field spec.
+    """
     if not isinstance(o, Sequence):
         o, i = [o], [i]
     res = []
     for (ao, ai) in zip(o, i):
-        res.append(ao.eq(ai))
+        #print ("eq", ao, ai)
+        if isinstance(ao, Record):
+            for idx, (field_name, field_shape, _) in enumerate(ao.layout):
+                if isinstance(field_shape, Layout):
+                    rres = eq(ao.fields[field_name], ai.fields[field_name])
+                else:
+                    rres = eq(ao.fields[field_name], ai[field_name])
+                res += rres
+        else:
+            res.append(ao.eq(ai))
     return res
 
 
-class BufferedPipeline:
-    """ buffered pipeline stage.  data and strobe signals travel in sync.
-        if ever the input is ready and the output is not, processed data
-        is stored in a temporary register.
-
-        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.data    >>in   stage   n.data    out>>   stage+1
-                              |             |
-                            process --->----^
-                              |             |
-                              +-- r_data ->-+
-
-        input data p.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
-        output (update_output).  however if ever there is a stall, it goes
-        into r_data instead [update_buffer()].
-
-        when the non-stall condition is released, r_data is the first
-        to be transferred to the output [flush_buffer()], and the stall
-        condition cleared.
-
-        on the next cycle (as long as stall is not raised again) the
-        input may begin to be processed and transferred directly to output.
+class PipelineBase:
+    """ Common functions for Pipeline API
     """
-    def __init__(self, stage):
+    def __init__(self, stage, in_multi=None):
         """ pass in a "stage" which may be either a static class or a class
-            instance, which has three functions:
+            instance, which has four functions (one optional):
             * ispec: returns input signals according to the input specification
             * ispec: returns output signals to the output specification
             * process: takes an input instance and returns processed data
+            * setup: performs any module linkage if the stage uses one.
 
-            p.data -> process() -> result --> n.data
-                                     |           ^
-                                     |           |
-                                     +-> r_data -+
+            User must also:
+            * add i_data member to PrevControl and
+            * add o_data member to NextControl
         """
         self.stage = stage
 
         # set up input and output IO ACK (prev/next ready/valid)
-        self.p = PrevControl()
+        self.p = PrevControl(in_multi)
         self.n = NextControl()
 
-        # set up the input and output data
-        self.p.data = stage.ispec() # input type
-        self.r_data = stage.ospec() # all these are output type
-        self.result = stage.ospec()
-        self.n.data = stage.ospec()
-
     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 self.n.connect_to_next(nxt.p)
 
@@ -150,63 +164,88 @@ class BufferedPipeline:
         """ helper function to connect stage to an input source.  do not
             use to connect stage-to-stage!
         """
-        return [self.p.i_valid.eq(prev.p.i_valid),
-                prev.p.o_ready.eq(self.p.o_ready),
-                eq(self.p.data, prev.p.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.n.o_valid.eq(self.n.o_valid),
-                self.n.i_ready.eq(nxt.n.i_ready),
-                eq(nxt.n.data, self.n.data),
-               ]
+        return self.n.connect_out(nxt.n)
 
     def set_input(self, i):
         """ helper function to set the input data
         """
-        return eq(self.p.data, i)
+        return eq(self.p.i_data, i)
 
-    def update_buffer(self):
-        """ copies the result into the intermediate register r_data,
-            which will need to be outputted on a subsequent cycle
-            prior to allowing "normal" operation.
-        """
-        return eq(self.r_data, self.result)
+    def ports(self):
+        return [self.p.i_valid, self.n.i_ready,
+                self.n.o_valid, self.p.o_ready,
+                self.p.i_data, self.n.o_data   # XXX need flattening!
+               ]
 
-    def update_output(self):
-        """ copies the (combinatorial) result into the output
-        """
-        return eq(self.n.data, self.result)
 
-    def flush_buffer(self):
-        """ copies the *intermediate* register r_data into the output
-        """
-        return eq(self.n.data, self.r_data)
+class BufferedPipeline(PipelineBase):
+    """ buffered pipeline stage.  data and strobe signals travel in sync.
+        if ever the input is ready and the output is not, processed data
+        is stored in a temporary register.
 
-    def ports(self):
-        return [self.p.data, self.n.data]
+        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 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
+        output (update_output).  however if ever there is a stall, it goes
+        into r_data instead [update_buffer()].
+
+        when the non-stall condition is released, r_data is the first
+        to be transferred to the output [flush_buffer()], and the stall
+        condition cleared.
+
+        on the next cycle (as long as stall is not raised again) the
+        input may begin to be processed and transferred directly to output.
+    """
+    def __init__(self, stage):
+        PipelineBase.__init__(self, stage)
+
+        # set up the input and output data
+        self.p.i_data = stage.ispec() # input type
+        self.n.o_data = stage.ospec()
 
     def elaborate(self, platform):
         m = Module()
+
+        result = self.stage.ospec()
+        r_data = self.stage.ospec()
         if hasattr(self.stage, "setup"):
-            self.stage.setup(m, self.p.data)
+            self.stage.setup(m, self.p.i_data)
 
         # establish some combinatorial temporaries
+        p_i_valid = Signal(reset_less=True)
         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.n.o_valid),
-                     i_p_valid_o_p_ready.eq(self.p.i_valid & self.p.o_ready),
+        vlen = len(self.p.i_valid)
+        if vlen > 1: # multi-bit case: valid only when i_valid is all 1s
+            all1s = Const(-1, (len(self.p.i_valid), False))
+            m.d.comb += p_i_valid.eq(self.p.i_valid == all1s)
+        else: # single-bit i_valid case
+            m.d.comb += p_i_valid.eq(self.p.i_valid)
+        m.d.comb += [ o_n_validn.eq(~self.n.o_valid),
+                     i_p_valid_o_p_ready.eq(p_i_valid & self.p.o_ready),
         ]
 
         # store result of processing in combinatorial temporary
-        with m.If(self.p.i_valid): # input is valid: process it
-            m.d.comb += eq(self.result, self.stage.process(self.p.data))
+        #with m.If(self.p.i_valid): # input is valid: process it
+        m.d.comb += eq(result, self.stage.process(self.p.i_data))
         # if not in stall condition, update the temporary register
         with m.If(self.p.o_ready): # not stalled
-            m.d.sync += self.update_buffer()
+            m.d.sync += eq(r_data, result) # update buffer
 
         #with m.If(self.p.i_rst): # reset
         #    m.d.sync += self.n.o_valid.eq(0)
@@ -214,13 +253,13 @@ class BufferedPipeline:
         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.n.o_valid.eq(self.p.i_valid),
-                             self.update_output(),
+                m.d.sync += [self.n.o_valid.eq(p_i_valid),
+                             eq(self.n.o_data, result), # update output
                             ]
             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.n.o_valid.eq(1),
-                             self.flush_buffer(),
+                             eq(self.n.o_data, r_data), # flush buffer
                              # clear stall condition, declare register empty.
                              self.p.o_ready.eq(1),
                             ]
@@ -228,23 +267,18 @@ class BufferedPipeline:
 
         # (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.n.o_valid.eq(self.p.i_valid),
+            m.d.sync += [self.n.o_valid.eq(p_i_valid),
                          self.p.o_ready.eq(1), # Keep the buffer empty
                          # set the output data (from comb result)
-                         self.update_output(),
+                         eq(self.n.o_data, result),
                         ]
         # (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.p.o_ready.eq(~(self.p.i_valid & self.n.o_valid))
+            m.d.sync += self.p.o_ready.eq(~(p_i_valid & self.n.o_valid))
 
         return m
 
-    def ports(self):
-        return [self.p.i_valid, self.n.i_ready,
-                self.n.o_valid, self.p.o_ready,
-               ]
-
 
 class ExampleAddStage:
     """ an example of how to use the buffered pipeline, as a class instance
@@ -301,67 +335,48 @@ class ExampleBufPipe(BufferedPipeline):
         BufferedPipeline.__init__(self, ExampleStage)
 
 
-class CombPipe:
+class CombPipe(PipelineBase):
     """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
+    r_data : Signal, input_shape
+        A temporary (buffered) copy of a prior (valid) input
+    result: Signal, output_shape
         The output of the combinatorial logic
     """
 
     def __init__(self, stage):
-        self.stage = stage
+        PipelineBase.__init__(self, 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.data = stage.ispec() # input type
-        self.r_data = stage.ispec() # input type
-        self.result = stage.ospec() # output data
-        self.n.data = stage.ospec() # output type
-        self.n.data.name = "outdata"
-
-    def set_input(self, i):
-        """ helper function to set the input data
-        """
-        return eq(self.p.data, i)
+        self.p.i_data = stage.ispec() # input type
+        self.n.o_data = stage.ospec() # output type
 
     def elaborate(self, platform):
         m = Module()
+
+        r_data = self.stage.ispec() # input type
+        result = self.stage.ospec() # output data
         if hasattr(self.stage, "setup"):
-            self.stage.setup(m, self.r_data)
-        m.d.comb += eq(self.result, self.stage.process(self.r_data))
+            self.stage.setup(m, r_data)
+
+        m.d.comb += eq(result, self.stage.process(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.data)
-        m.d.comb += eq(self.n.data, self.result)
+            m.d.sync += eq(r_data, self.p.i_data)
+        m.d.comb += eq(self.n.o_data, result)
         return m
 
-    def ports(self):
-        return [self.p.data, self.n.data]
-
 
 class ExampleCombPipe(CombPipe):
     """ an example of how to use the combinatorial pipeline.