Added SILC Rand API, SILC Global Variables API and silcruntime.h.in

[runtime.git] / lib / silcutil / silcrand.c

diff --git a/lib/silcutil/silcrand.c b/lib/silcutil/silcrand.c
new file mode 100644 (file)
index 0000000..10dcc2c
--- /dev/null
+++ b/lib/silcutil/silcrand.c
@@ -0,0 +1,149 @@
+/*
+
+  silcrand.c
+
+  Author: Pekka Riikonen <priikone@silcnet.org>
+
+  Copyright (C) 2008 Pekka Riikonen
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; version 2 of the License.
+
+  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.
+
+*/
+
+#include "silcruntime.h"
+
+/************************* Types and definitions ****************************/
+
+/* Random number state context size */
+#define SILC_RAND_STATE_SIZE 624
+#define SILC_RAND_STATE_FULL_SIZE ((SILC_RAND_STATE_SIZE + 1) *        \
+                                  sizeof(SilcUInt32))
+
+/* State position offset */
+#define SILC_RAND_STATE_POS (SILC_RAND_STATE_SIZE + 1) - 1
+
+/************************ Static utility functions **************************/
+
+/* Refresh the state */
+
+void silc_rand_refresh(SilcUInt32 *rs)
+{
+  SilcUInt32 i, c;
+
+  for (i = 0; i < SILC_RAND_STATE_SIZE - 1; i++) {
+    c = (rs[i] & 0x80000000UL) | (rs[i + 1] & 0x7fffffffUL);
+    if (c & 1)
+      rs[i] = rs[(i + 397) % SILC_RAND_STATE_SIZE] ^ (c >> 1) ^ 0x9908b0dfUL;
+    else
+      rs[i] = rs[(i + 397) % SILC_RAND_STATE_SIZE] ^ (c >> 1);
+  }
+
+  c = (rs[i] & 0x80000000UL) | (rs[0] & 0x7fffffffUL);
+  if (c & 1)
+    rs[i] = rs[(i + 397) % SILC_RAND_STATE_SIZE] ^ (c >> 1) ^ 0x9908b0dfUL;
+  else
+    rs[i] = rs[(i + 397) % SILC_RAND_STATE_SIZE] ^ (c >> 1);
+
+  rs[SILC_RAND_STATE_POS] = 0;
+}
+
+/* Seed */
+
+static void silc_rand_seed_state(SilcUInt32 *rs, SilcUInt32 seed)
+{
+  SilcUInt32 c, i;
+
+  rs[0] = seed;
+  for (i = 1; i < SILC_RAND_STATE_SIZE; i++) {
+    c = rs[i - 1];
+    rs[i] = (1812433253UL * ((c ^ (c >> 30)) + 1));
+  }
+
+  silc_rand_refresh(rs);
+}
+
+/* Return random state or create it. */
+
+static SilcUInt32 *silc_rand_state(SilcBool seed)
+{
+  SilcUInt32 *rs;
+
+  rs = silc_global_get_var("srtrs", TRUE);
+  if (!rs) {
+    rs = silc_global_set_var("srtrs", SILC_RAND_STATE_FULL_SIZE, NULL, TRUE);
+    if (!rs)
+      return NULL;
+
+    if (seed)
+      silc_rand_seed_state(rs, (SilcUInt32)silc_time_usec());
+  }
+
+  return rs;
+}
+
+/* Temper next position and return the value */
+
+SilcUInt32 silc_rand_temper(SilcUInt32 *rs)
+{
+  SilcUInt32 val;
+
+  /* Refresh if necessary */
+  if (++rs[SILC_RAND_STATE_POS] >= SILC_RAND_STATE_SIZE)
+    silc_rand_refresh(rs);
+
+  /* Temper */
+  val = rs[rs[SILC_RAND_STATE_POS]];
+  val = val ^ (val >> 11);
+  val = val ^ ((val << 7) & 0x9d2c5680UL);
+  val = val ^ ((val << 15) & 0xefc60000UL);
+  return val ^ (val >> 18);
+}
+
+/******************************* SILC Rand API ******************************/
+
+/* Seed the generator */
+
+void silc_rand_seed(SilcUInt32 seed)
+{
+  SilcUInt32 *rs;
+
+  rs = silc_rand_state(FALSE);
+  if (!rs)
+    return;
+
+  silc_rand_seed_state(rs, seed);
+}
+
+/* Return 32-bit random number */
+
+SilcUInt32 silc_rand(void)
+{
+  SilcUInt32 *rs;
+
+  rs = silc_rand_state(TRUE);
+  if (!rs)
+    return 0x23456789 + (SilcUInt32)silc_time_usec();
+
+  return silc_rand_temper(rs);
+}
+
+/* Return 64-bit random number */
+
+SilcUInt64 silc_rand64(void)
+{
+  SilcUInt32 *rs;
+
+  rs = silc_rand_state(TRUE);
+  if (!rs)
+    return 0x1234567891234567 + silc_time_usec();
+
+  return (SilcUInt64)(((SilcUInt64)silc_rand_temper(rs) << 32) |
+                     silc_rand_temper(rs));
+}