From: lkcl <lkcl@web>
Date: Fri, 19 Feb 2021 19:43:11 +0000 (+0000)
Subject: (no commit message)
X-Git-Tag: convert-csv-opcode-to-binary~149
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=26442aee12a431a18591ff7e2c017e8731d633d7;p=libreriscv.git

---

diff --git a/openpower/sv/vector_ops.mdwn b/openpower/sv/vector_ops.mdwn
index d9e401db7..c954b8ab4 100644
--- a/openpower/sv/vector_ops.mdwn
+++ b/openpower/sv/vector_ops.mdwn
@@ -264,6 +264,14 @@ used not just for carry lookahead, also a special type of predication mask opera
 * <https://i.stack.imgur.com/QSLKY.png>
 * <https://stackoverflow.com/questions/27971757/big-integer-addition-code>
   `((P|G)+G)^P`
+* <https://en.m.wikipedia.org/wiki/Carry-lookahead_adder>
+
+     P = (A | B) & Ci
+     G = (A & B)
+
+Stackoverflow algorithm `((P|G)+G)^P` works on the cumulated bits of P and G from associated vector units (P and G are integers here).  The result of the algorithm is the new carry-in which already includes ripple, one bit of carry per element.
+
+
 
 two versions: scalar int version and CR based version.