X-Git-Url: https://git.cryptolib.org/?a=blobdiff_plain;f=gf256mul.S;h=b269d3a4a1b760d2d372598bb0cbfdf87de1009c;hb=02ac3b653f3a11f284cc1a0cb0e983575f2f431b;hp=02e85e95c9003999a0c25ba4982edf36006ee296;hpb=4469def3e210fc904cfefc5b158fc6d4dc5f6e47;p=avr-crypto-lib.git

diff --git a/gf256mul.S b/gf256mul.S
index 02e85e9..b269d3a 100644
--- a/gf256mul.S
+++ b/gf256mul.S
@@ -1,6 +1,6 @@
 /* gf256mul.S */
 /*
-    This file is part of the Crypto-avr-lib/microcrypt-lib.
+    This file is part of the AVR-Crypto-Lib.
     Copyright (C) 2008  Daniel Otte (daniel.otte@rub.de)
 
     This program is free software: you can redistribute it and/or modify
@@ -26,30 +26,57 @@
  * 
  */
 
+#include <avr/io.h>
+#define OPTIMIZE_SMALL_A
 
 /*
  * param a: r24
- * param b; r22
+ * param b: r22
  * param reducer: r20
  */
-A = 21
+A = 23
 B = 22
 P = 24
 .global gf256mul
+
+#ifdef OPTIMIZE_SMALL_A
+gf256mul:
+	mov A, r24
+	clr r24
+1:	
+	lsr A
+	breq 4f
+	brcc 2f
+	eor P, B
+2:
+	lsl B
+	brcc 3f
+	eor B, r20	
+3:
+	rjmp 1b
+4:
+	brcc 2f
+	eor P, B
+2:
+	ret
+
+#else
+
 gf256mul:
 	mov r21, r24
 	clr r24
 	ldi r25, 8
 1:	
-	lsr B
+	lsr A
 	brcc 2f
-	eor P, A
+	eor P, B
 2:
-	lsl A
+	lsl B
 	brcc 3f
-	eor A, r20	
+	eor B, r20	
 3:
 	dec r25
 	brne 1b
 	ret
 
+#endif