X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/39be270832d86dfa24a84cc0e31fa8f3442f4136..7280f7f44cfae62f6d34761ac88aa19da7da5dd8:/maurer.h

diff --git a/maurer.h b/maurer.h
index cd74e8c..7373660 100644
--- a/maurer.h
+++ b/maurer.h
@@ -1,13 +1,13 @@
 /* -*-c-*-
  *
- * $Id: maurer.h,v 1.1 2000/06/17 11:29:49 mdw Exp $
+ * $Id: maurer.h,v 1.3 2004/04/08 01:36:15 mdw Exp $
  *
  * Maurer's universal statistical test
  *
  * (c) 2000 Straylight/Edgeware
  */
 
-/*----- Licensing notice --------------------------------------------------* 
+/*----- Licensing notice --------------------------------------------------*
  *
  * This file is part of Catacomb.
  *
@@ -15,26 +15,18 @@
  * it under the terms of the GNU Library General Public License as
  * published by the Free Software Foundation; either version 2 of the
  * License, or (at your option) any later version.
- * 
+ *
  * Catacomb is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Library General Public License for more details.
- * 
+ *
  * You should have received a copy of the GNU Library General Public
  * License along with Catacomb; if not, write to the Free
  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: maurer.h,v $
- * Revision 1.1  2000/06/17 11:29:49  mdw
- * Maurer's universal statistical test.
- *
- */
-
 #ifndef CATACOMB_MAURER_H
 #define CATACOMB_MAURER_H
 
@@ -46,24 +38,74 @@
 
 #include <mLib/bits.h>
 
+/*----- Data structures ---------------------------------------------------*/
+
+typedef struct maurer_ctx {
+  unsigned l;				/* Chunk size, in bits */
+  uint32 a;				/* Bitscanner accumulator */
+  unsigned b;				/* Number of bits in accumulator */
+  unsigned long n;			/* Number of chunks read so far */
+  double x;				/* Statistic value */
+  unsigned long *t;			/* Offset table */
+} maurer_ctx;
+
 /*----- Functions provided ------------------------------------------------*/
 
+/* --- @maurer_init@ --- *
+ *
+ * Arguments:	@maurer_ctx *m@ = pointer to a context to initialize
+ *		@unsigned l@ = number of bits to take at a time
+ *
+ * Returns:	Minimum recommended amount of data to test.
+ *
+ * Use:		Initializes a Maurer testing context.  Note that @l@ values
+ *		larger than 16 are not supported, and values less than 6 can
+ *		give bizarre results.
+ */
+
+extern unsigned long maurer_init(maurer_ctx */*m*/, unsigned /*l*/);
+
+/* --- @maurer_test@ --- *
+ *
+ * Arguments:	@maurer_ctx *m@ = pointer to a Maurer testing context
+ *		@const void *buf@ = pointer to a buffer of data
+ *		@size_t sz@ = size of the buffer
+ *
+ * Returns:	---
+ *
+ * Use:		Scans a buffer of data and updates the testing context.
+ */
+
+extern void maurer_test(maurer_ctx */*m*/,
+			const void */*buf*/, size_t /*sz*/);
+
+/* --- @maurer_done@ --- *
+ *
+ * Arguments:	@maurer_ctx *m@ = pointer to a Maurer testing context
+ *
+ * Returns:	The statistic %$Z_u = (X_u - \mu)/\sigma$%, which should be
+ *		normally distributed with a mean of 0 and variance of 1.
+ *
+ * Use:		Returns the result of Maurer's universal statistical test.
+ *		Also frees the memory allocated during initialization.
+ *
+ *		If insufficient data was received, the value @HUGE_VAL@ is
+ *		returned.
+ */
+
+extern double maurer_done(maurer_ctx */*m*/);
+
 /* --- @maurer@ --- *
  *
  * Arguments:	@const octet *p@ = pointer to a buffer of data
  *		@size_t sz@ = size of the buffer
  *		@unsigned l@ = number of bits to take at a time
  *
- * Returns:	The statistic %$Z_u = (X_u - \mu)/\sigma$%, which should be
- *		normally distributed with a mean of zero and standard
- *		deviation of 1.
- *
- * Use:		Performs Maurer's universal statistical test on a buffer of
- *		data.  You must ensure that the buffer size @sz@ is larger
- *		than %$11 l \cdot 2^l$% bits long, and ideally much larger.
+ * Returns:	The statistic %$Z_u$%.
  *
- *		Note that, under Unix systems, this function requires the
- *		maths library.
+ * Use:		Simple interface to Maurer's universal statistical test.  For
+ *		large %$l$% you should use the more complicated restartable
+ *		interface.
  */
 
 extern double maurer(const octet */*p*/, size_t /*sz*/, unsigned /*l*/);