From: Konstantinos Margaritis <konstantinos.margaritis@vectorcamp.gr>
Date: Sat, 29 Apr 2023 15:29:32 +0000 (+0000)
Subject: Result needs rounding so add +1 to prod*
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=102dda243180cc0a0ccfe5ed9e5ced2b775f7232;p=openpower-isa.git

Result needs rounding so add +1 to prod*
---

diff --git a/openpower/isa/butterfly.mdwn b/openpower/isa/butterfly.mdwn
index 555e8abd..94840b03 100644
--- a/openpower/isa/butterfly.mdwn
+++ b/openpower/isa/butterfly.mdwn
@@ -13,8 +13,8 @@ Pseudo-code:
     n <- SH
     sum <- (RT) + (RA)
     diff <- (RT) - (RA)
-    prod1 <- MULS(RB, sum)[XLEN:(XLEN*2)-1]
-    prod2 <- MULS(RB, diff)[XLEN:(XLEN*2)-1]
+    prod1 <- MULS(RB, sum)[XLEN:(XLEN*2)-1] + 1
+    prod2 <- MULS(RB, diff)[XLEN:(XLEN*2)-1] + 1
     res1 <- ROTL64(prod1, XLEN-n)
     res2 <- ROTL64(prod2, XLEN-n)
     m <- MASK(n, (XLEN-1))