[Libre-soc-bugs] [Bug 458] PartitionedSignal needs nmigen constructs "m.If", Switch etc

[bugzilla-daemon at libre-soc.org]

https://bugs.libre-soc.org/show_bug.cgi?id=458

--- Comment #5 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---


lune 437:
                if if_test is not None:
                    if_test = Value.cast(if_test)
                    if len(if_test) != 1:
                        if_test = if_test.bool()


that was what i was talking about might need a function "isconsideredbool"
instead of len iftest !=1

line 447:


            self._statements.append(Switch(Cat(tests), cases,
                src_loc=src_loc, case_src_locs=dict(zip(cases, if_src_locs))))

the Switch there can be Value.__Switch__ and that function
call standard Switch.

the PartitionedSignal.__Switch__ variant instead does:

    for i, pbit in enumerate(self.partition_bits):
        totest = Part(test, i)
        ...

and creates *multiple* switch/case statements, each of which takes
a chunk at a time rather than does the entire lot as one hit.

8 paritions means *EIGHT* completely separate switch/cases, one for
each partition.

the reason why this works is because the HDL gates are going to be
there anyway, and the rule for PartitionedBool is that ALL bits
have to be set across the whole partition.

therefore, each "column" in the partition receives a copy
of the same "if" decision.

-- 
You are receiving this mail because:
You are on the CC list for the bug.