Update of /project/crypticl/cvsroot/crypticl/src
In directory clnet:/tmp/cvs-serv6364
Modified Files:
common.lisp
Log Message:
Adding utils needed by SHA-256.
--- /project/crypticl/cvsroot/crypticl/src/common.lisp 2005/10/01 16:34:44 1.4
+++ /project/crypticl/cvsroot/crypticl/src/common.lisp 2007/01/06 12:42:11 1.5
@@ -104,14 +104,22 @@
(ldb (byte 32 0) (reduce #'+ args)))
-(defun 32-left-rot (a by)
+(defun left-rot-32 (a by)
"Left rotation modulo 32. If number longer than 32 bits, ignore extra bits."
- (let ((break (- 32 by)))
- (dpb (ldb (byte break 0) a)
- (byte break by)
- (ldb (byte by break)
- a))))
-
+ (let ((pivot (- 32 by)))
+ (dpb (ldb (byte pivot 0) a)
+ (byte pivot by)
+ (ldb (byte by pivot) a))))
+
+(defun right-rot-32 (a by)
+ "Right rotation modulo 32. If number longer than 32 bits, ignore extra bits.
+
+1) Shift the (32 - by) left bits to the right by places
+2) Shift the right by bits all over to the left.
+"
+ (let ((leftpart (- 32 by)))
+ (+ (ash a (- by))
+ (ash (ldb (byte by 0) a) leftpart))))
(defun make-string-reader-function (string)
"Return a function that reads one byte at a time from a string or nil
