X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=common-src%2Fsimpleprng.c;fp=common-src%2Fsimpleprng.c;h=684e5de242f4f954e2153830a31699e073f9d5a1;hb=2627875b7d18858bc1f9f7652811e4d8c15a23eb;hp=0000000000000000000000000000000000000000;hpb=fb2bd066c2f8b34addafe48d62550e3033a59431;p=debian%2Famanda

diff --git a/common-src/simpleprng.c b/common-src/simpleprng.c
new file mode 100644
index 0000000..684e5de
--- /dev/null
+++ b/common-src/simpleprng.c
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2005-2008 Zmanda Inc.  All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program 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 General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ * Contact information: Zmanda Inc, 465 S Mathlida Ave, Suite 300
+ * Sunnyvale, CA 94086, USA, or: http://www.zmanda.com
+ */
+
+#include "simpleprng.h"
+
+/* A *very* basic linear congruential generator; values are as cited in
+ * http://en.wikipedia.org/wiki/Linear_congruential_generator for Numerical Recipes */
+
+#define A 1664525
+#define C 1013904223
+
+void
+simpleprng_seed(
+    simpleprng_state_t *state,
+    guint32 seed)
+{
+    g_assert(seed != 0);
+    *state = seed;
+}
+
+guint32 simpleprng_rand(
+    simpleprng_state_t *state)
+{
+    return (*state = (A * (*state)) + C);
+}
+
+void simpleprng_fill_buffer(
+    simpleprng_state_t *state,
+    gpointer buf,
+    size_t len)
+{
+    guint8 *p = buf;
+    while (len--) {
+	*(p++) = simpleprng_rand_byte(state);
+    }
+}
+
+gboolean simpleprng_verify_buffer(
+    simpleprng_state_t *state,
+    gpointer buf,
+    size_t len)
+{
+    guint8 *p = buf;
+    while (len--) {
+	guint8 expected = simpleprng_rand_byte(state);
+	guint8 got = *p;
+	if (expected != got) {
+	    g_fprintf(stderr,
+		    "random value mismatch in buffer %p, offset %zd: got 0x%02x, expected 0x%02x\n", 
+		    buf, (size_t)(p-(guint8*)buf), (int)got, (int)expected);
+	    return FALSE;
+	}
+	p++;
+    }
+
+    return TRUE;
+}