X-Git-Url: https://git.cryptolib.org/?a=blobdiff_plain;f=arcfour-asm.S;h=1ef8218ce971a608ffaf096959dc40fb63141804;hb=8f855d283a31a468ea014774c4723a8b77b81644;hp=ec0eeebc879aa7b6706f45031f40a0b257fbea41;hpb=6bca96e560e6097aa5b225fad67f2e2a27f4182f;p=avr-crypto-lib.git

diff --git a/arcfour-asm.S b/arcfour-asm.S
index ec0eeeb..1ef8218 100644
--- a/arcfour-asm.S
+++ b/arcfour-asm.S
@@ -1,6 +1,6 @@
 /* arcfour-asm.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
@@ -16,6 +16,7 @@
     You should have received a copy of the GNU General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
+
 /* 
  * File:        arcfour-asm.S
  * Author:      Daniel Otte
@@ -25,68 +26,60 @@
  * 
  */
  
+#include <avr/io.h>
+#include "avr-asm-macros.S"
+ 
  /* +---+---+---------------------+
  *  | i | j | ......<256>........ |
  *  +---+---+---------------------+
  */
  
 .global arcfour_init
-
-;== arcfour_init ==
-;  this function initialises the context
-; param1: 16-bit pointer to a ctx struct
-;	given in r25,r24
-; param2: 16-bit pointer to a key
-;	given in r23,r22
-; param1: 8-bit integer indicating keylength in byte
-;	given in 	r20
-
+/*
+ *== arcfour_init ==
+ *  this function initialises the context
+ * param1: 16-bit pointer to the key
+ *	given in r24:r25
+ * param2: 8-bit integer indicating keylength in byte
+ *	given in r22
+ * param3: 16-bit pointer to a ctx struct
+ *	given in r20:r21
+ */
 arcfour_init:
-	push r29
-	push r28
-	push r2
-	
-	movw r26, r24	/* X points to ctx */
-	movw r30, r22	/* Z points to key */
+	push_ r28, r29
+	movw r26, r20   /* X points to ctx */
+	movw r30, r24   /* Z points to key */
 	st X+, r1
-	st X+, r1		/* X points to S */
+	st X+, r1       /* X points to S */
+	movw r20, r26   /* store pointer to S in r21:r20 */
 	
 1:		
 	st X+, r1 
 	inc r1
 	brne 1b
 	
-	adiw r24, 2		/* r24:r25 points to S */
-	clr r21			/* r21 is j */
-	mov r18, r20		/* r18 is keyindex counter */
+	movw r26, r20
+	add r22, r30         /* r18 is keyindex counter */
 	clr r0
+	clr r19
 2:
-	movw r26, r24
-	ld r19, Z+
-	add r21, r19		/* j+= key[i%length] */
-	
-	add r26, r1
-	adc r27, r0
-	ld r19, X
-	add r21, r19		/* j += S[i] */
-	
-	dec r18		/* check the key-index counter */
+	ld r23, X
+	ld r18, Z+
+	add r19, r18
+	add r19, r23
+	movw r28, r20   /* load pointer to S in Y */
+	add r28, r19
+	adc r29, r1
+	ld r18, Y
+	st Y,  r23
+	st X+, r18
+	cp r30, r22
 	brne 3f
-	movw r30, r22
-	mov r18, r20
-3:	/* now swap(S[i], S[j]) */ /* r19 is still S[i] */
-	movw r28, r24 
-	add r28, r21
-	adc r29, r0		/* Y points to S[j]*/
-	ld r2, Y
-	st Y, r19
-	st X, r2	
-	inc r1
+	movw r30, r24
+3:		
+	inc r0
 	brne 2b	
-	
-	pop r2
-	pop r28
-	pop r29
+	pop_ r29, r28
 	ret
 
 /*