[libre-riscv-dev] [Bug 208] implement CORDIC in a general way sufficient to do transcendentals

bugzilla-daemon at libre-soc.org bugzilla-daemon at libre-soc.org
Tue May 5 17:12:25 BST 2020


https://bugs.libre-soc.org/show_bug.cgi?id=208

--- Comment #50 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
btw 12 stages is too many, because we need a minimum of one FunctionUnit
"managing" (matching up) source operands and results.

each extra Function Unit added creates an Order N^2 increase in the overall
size of the Dependency Matrices.

so - and i don't mean right now - if this can be either:

* cut into two separate pipelines (partial data fed back as a micro-op)
* number of combinatorial blocks increased to 5 or 6

we stand a chance of keeping the FU count down (8 is ok).

have to think that through carefully, how to do micro-ops.

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