commit e7c5afb149a906bc0f8d2706e6a266a080fa223d parent fc4a3ef24f1290d891318fdd293c5c9245bc3d1a Author: Brian Swetland <swetland@frotz.net> Date: Sat, 24 Nov 2018 10:35:40 -0800 isa: some notes on possible changes Diffstat:
| M | docs/isa16v4.txt | | | 9 | +++++++++ |
1 file changed, 9 insertions(+), 0 deletions(-)
diff --git a/docs/isa16v4.txt b/docs/isa16v4.txt @@ -26,3 +26,12 @@ E 0111 11 bl Ra R7 = PC + 1, PC = Ra F 1fff alu Rc, Ra, si6 Rc = Ra <fn> ( Ex ? { Ev, si6[3:0] } : si6 ) * Ex reset to 0 after all ops but "ext" + +notes +----- +- consider changing ext to use si10 instead and the reclaimed two bits + to open up more instruction set space +- consider allowing ext to work with b/bl and/or bz/bnz for long branches +- in which case maybe si11->si10 and compact branch instruction footprint + a bit too +