From 6851ec9a1aa8cc911635c563b99e52c3641bfb5b Mon Sep 17 00:00:00 2001 From: lkcl Date: Mon, 30 Nov 2020 18:52:52 +0000 Subject: [PATCH] --- openpower/sv/16_bit_compressed.mdwn | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/openpower/sv/16_bit_compressed.mdwn b/openpower/sv/16_bit_compressed.mdwn index 17d6392c6..43bec717a 100644 --- a/openpower/sv/16_bit_compressed.mdwn +++ b/openpower/sv/16_bit_compressed.mdwn @@ -820,7 +820,7 @@ Pseudocode: # and back transitions left to implementor # (or for someone else to add) -## Phase 2 Compressed (16bit decoding) +### Phase 2: Compressed mode At this phase, knowing that the length is 16bit and the mode is either 10b or 16b, further analysis is required to determine if the 16bit.immediate encoding is active, and so on. This is a fully combinatorial block that **at no time** steps outside of the strict bounds already determined by Phase 1. @@ -833,7 +833,11 @@ At this phase, knowing that the length is 16bit and the mode is either 10b or 16 decode_16bit_nonimmed_mode(insn) From this point onwards each of the decode_xx functions perform straightforward combinatorial decoding of the 16 bits of "insn". In sone cases this involves further analysis of bit 1, in some cases (Cmaj.m = 0b010.1) even further deep-dive decoding is required (CR ops). *All* of it is entirely combinatorial and at **no time** involves changing of, or interaction with, or disruption of, the Phase 1 determination of Length+Mode (that has *already taken place* in an earlier decoding pipeline time-schedule) - + +### Phase 2: v3.0B mode + +Standard v3.0B decoders are deployed. Absolutely no interaction occurs with any 16 bit decoders or state. Absolutely no interaction with the earlier Phase 1 decoding occurs. Absolutely no interaction occurs whatsoever (assuming an implementation that does not perform macro-op fusion) between other multi-issued v3.0B instructions being decoded in parallel at this time. + ## Demo of encoding that's backward-compatible with PowerISA v3.1 in both LE and BE mode [[demo]] -- 2.30.2