From: lkcl <lkcl@web>
Date: Mon, 7 Mar 2022 17:06:17 +0000 (+0000)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls005_v1~3127
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=d296254025cfc91ec46a6377888c5efa4e241b1a;p=libreriscv.git

---

diff --git a/openpower/sv/bitmanip.mdwn b/openpower/sv/bitmanip.mdwn
index 444a935ce..01ac26492 100644
--- a/openpower/sv/bitmanip.mdwn
+++ b/openpower/sv/bitmanip.mdwn
@@ -532,7 +532,9 @@ arithmetic the modulo is to be set in an SPR
 ## Twin Butterfly (Tukey-Cooley) Mul-add-sub
 
 used in combination with SV FFT REMAP to perform
-a full NTT in-place
+a full NTT in-place. possible by having 3-in 2-out,
+to avoid the need for a temp register.  RS is written
+to as well as RT.
 
     gffmadd  RT,RA,RC,RB (Rc=0)
     gffmadd. RT,RA,RC,RB (Rc=1)