X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/ba6e6b64033b1f9de49feccb5c9cd438354481f7..0f00dc4c8eb47e67bc0f148c2dd109f73a451e0a:/rand/maurer.h

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+/* -*-c-*-
+ *
+ * Maurer's universal statistical test
+ *
+ * (c) 2000 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of Catacomb.
+ *
+ * Catacomb is free software; you can redistribute it and/or modify
+ * 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.
+ */
+
+#ifndef CATACOMB_MAURER_H
+#define CATACOMB_MAURER_H
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+/*----- Header files ------------------------------------------------------*/
+
+#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 %$Z_u$%.
+ *
+ * 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*/);
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+  }
+#endif
+
+#endif