[Libre-soc-bugs] [Bug 1155] O(n^2) multiplication REMAP mode(s)

[bugzilla-daemon at libre-soc.org]

https://bugs.libre-soc.org/show_bug.cgi?id=1155

--- Comment #4 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
svshape SVxd,SVyd,SVzd,SVRM,vf
0:5     6:10    11:15   16:20   21:24   25      26:31   name
PO      SVxd    SVyd    SVzd    SVRM    vf      XO      svshape

Fields:

SVxd - SV REMAP "xdim" (X-dimension)
SVyd - SV REMAP "ydim" (Y-dimension, sometimes used for sub-mode selection)
SVzd - SV REMAP "zdim" (Z-dimension)
SVRM - SV REMAP Mode (0b00000 for Matrix, 0b00001 for FFT etc.)

ok so SVyd is the de-facto selector for sub-modes: SVyd "bit 0" can
be used for selecting bigmul/prefix, under SVRM=0b0111, whereupon
bits 1-2 can be used for inversion and 2-3 for mirror...

damn damn damn 5 bits are needed: one for long-mul, one for carrysave

ah hang on i know: "/mrr" performs a full reverse, which in combination
with inverting either x or y order *back* again (single bit) you get
the full complement. i think.

so:

* bit 0 select bigmul or Prefx
* bit 1 select carrysave or longmul
* bit 2 select invert x (or y?)
* bit 3 mirror x (5 45 345 2345 12345 012345 instead of 0 01 012 ...)
* bit 4 mirror y (ditto)

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