+ 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()