prjxray

History

Rick Altherr 43e51dd5c1 Reformat existing Python files with yapf Signed-off-by: Rick Altherr <kc8apf@kc8apf.net>		2018-01-09 14:50:06 -08:00
..
.gitignore	clb_boutmux test. gitignore cleanup	2017-12-20 22:46:39 +01:00
Makefile	Add "make run" to fuzzers that did not have it yet	2018-01-04 13:49:50 +01:00
README.txt	clbn5ffmux fuzzer	2017-12-20 22:46:39 +01:00
generate.py	Reformat existing Python files with yapf	2018-01-09 14:50:06 -08:00
generate.sh	Document MUXF8 Vivado compatibility issue	2017-12-22 15:52:40 -08:00
generate.tcl	Set tcl.collectionResultDisplayLimit to unlimited in all fuzzers	2017-12-22 23:28:39 +01:00
top.py	Reformat existing Python files with yapf	2018-01-09 14:50:06 -08:00

README.txt

Purpose:
Document A5FFMUX family of CLB muxes

Algorithm:
*5FFMUX
Inputs can come from either the LUT6_2 NO5 output or the CLB NX input
To perturb the CLB the smallest, want LUT6 always instantiated
However, some routing congestion that would require putting FFs in bypass
(which turns out is actually okay, but didn't realize that at the time)
Decided instead ot instantiate LUT8, but not use the output
Turns out this is okay and won't optimize things away
So then, the 5FF D input is switched between the O5 output and an external CLB input

Outcome:
Bits are one hot encoded per mux position