From: lkcl <lkcl@web>
Date: Mon, 18 Apr 2022 21:34:56 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls005_v1~2710
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=6e987f94ac3fcf76ffc7d74e257d512907458483;p=libreriscv.git

---

diff --git a/openpower/sv/bitmanip/appendix.mdwn b/openpower/sv/bitmanip/appendix.mdwn
index 9f25e0dbe..ffd7bda50 100644
--- a/openpower/sv/bitmanip/appendix.mdwn
+++ b/openpower/sv/bitmanip/appendix.mdwn
@@ -188,7 +188,10 @@ As a result, a big-integer subtract and multiply may be carried out
 in only 3 instructions, one of which is setting a scalar integer to
 zero.
 
-## EXT004 Opcode map
+An Rc=1 variant tests not against RT but RA, which allows detection
+of a fixup in Knuth Algorithm D: the condition where RA is not zero.
+
+# EXT004 Opcode map
 
 See Power ISA v3.1, Book III, Appendix D, Table 13 (sheet 7 of 8), p1357.
 Proposed is the addition of `msubxd` (**DRAFT, NOT APPROVED**) which is