[libre-riscv-dev] partitioned compare and mux
Luke Kenneth Casson Leighton
lkcl at lkcl.net
Sun Feb 9 18:16:49 GMT 2020
On Sun, Feb 9, 2020 at 3:05 PM Luke Kenneth Casson Leighton
<lkcl at lkcl.net> wrote:
> oh - just realised, would you agree, is it the case that we have to
> "slide down" the carry-out to the beginning of the partition? using
> one of those mux-cascades?
bored-on-a-sunday syndrome :)
wrote a class MoveMSBDown  (i'm rubbish at names), my take is, it
would need to be used at line 217 on adder.py?
MoveMSBDown does what it says: moves the MSB (of each partition) down
to the LSB position. it does so by first "rippling" the MSB across
the entire partition (starting at MSB and working down) using a
Mux-cascade, then, rather than output that directly it ANDs the
intermediate result with the partition gates. that has the effect of
only outputting the MSB in the position of the partition's LSB.
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