From 2f89c4687b258a5476576e47c6d436397b13db12 Mon Sep 17 00:00:00 2001
From: bg <bg@nerilex.org>
Date: Tue, 8 Jul 2014 21:16:21 +0200
Subject: [PATCH] C-code for gf256-multiplication in comment

---
 gf256mul/gf256mul.S | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/gf256mul/gf256mul.S b/gf256mul/gf256mul.S
index b269d3a..d202d84 100644
--- a/gf256mul/gf256mul.S
+++ b/gf256mul/gf256mul.S
@@ -62,8 +62,26 @@ gf256mul:
 
 #else
 
+/*
+
+uint8_t gf256mul(uint8_t a, uint8_t b, uint8_t p) {
+	uint8_t r = 0, c = 8;
+	do {
+	    if (a & 1) {
+	        r ^= b;
+	    }
+	    a >>= 1;
+	    if (b & 0x80) {
+	        b ^= p;
+	    }
+	    b <<= 1;
+	} while (--c);
+	return r;
+}
+
+ */
 gf256mul:
-	mov r21, r24
+	mov A, r24
 	clr r24
 	ldi r25, 8
 1: