From: Jacob Lifshay <programmerjake@gmail.com>
Date: Fri, 18 Mar 2022 02:46:44 +0000 (-0700)
Subject: read all inputs before writing to any outputs
X-Git-Tag: opf_rfc_ls005_v1~3018
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=d55ca21896083a8f202917609e4e218737c1cc16;p=libreriscv.git

read all inputs before writing to any outputs
in case an input overlaps with an output register.
---

diff --git a/openpower/sv/bitmanip.mdwn b/openpower/sv/bitmanip.mdwn
index 548d487bc..ab2c7e2a9 100644
--- a/openpower/sv/bitmanip.mdwn
+++ b/openpower/sv/bitmanip.mdwn
@@ -594,9 +594,13 @@ cltmadd RT, RA, RB, RC
 
 TODO: add link to explanation for where `RS` comes from.
 
-``` 
-(RT) = RC ^ clmul((RA), (RB))
-(RS) = RA ^ RC
+```
+a = (RA)
+c = (RC)
+# read all inputs before writing to any outputs in case
+# an input overlaps with an output register.
+(RT) = clmul(a, (RB)) ^ c
+(RS) = a ^ c
 ```
 
 ## `cldivrem` Carry-less Division and Remainder
@@ -691,9 +695,13 @@ gfbtmadd RT, RA, RB, RC
 
 TODO: add link to explanation for where `RS` comes from.
 
-``` 
-(RT) = gfbmadd((RA), (RB), (RC))
-(RS) = RA ^ RC
+```
+a = (RA)
+c = (RC)
+# read all inputs before writing to any outputs in case
+# an input overlaps with an output register.
+(RT) = gfbmadd(a, (RB), c)
+(RS) = a ^ c
 ```
 
 ## `gfbinv` -- Binary Galois Field `GF(2^m)` Inverse