From 056f4d287bf0d58ce70a4a77dc85107db5420540 Mon Sep 17 00:00:00 2001
From: Yamagi Burmeister <yamagi@yamagi.org>
Date: Sat, 2 Jun 2012 10:56:40 +0200
Subject: [PATCH] Add rand.c, an implementation of G. Marsaglia KISS PRNG

---
 Makefile                   |  2 ++
 src/common/header/common.h |  4 +++
 src/common/rand.c          | 69 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 75 insertions(+)
 create mode 100644 src/common/rand.c

diff --git a/Makefile b/Makefile
index 923087d4..2226dea3 100644
--- a/Makefile
+++ b/Makefile
@@ -353,6 +353,7 @@ CLIENT_OBJS_ := \
 	src/common/misc.o \
 	src/common/netchan.o \
 	src/common/pmove.o \
+	src/common/rand.o \
 	src/common/szone.o \
 	src/common/zone.o \
 	src/common/command/cmd_execution.o \
@@ -403,6 +404,7 @@ SERVER_OBJS_ := \
 	src/common/misc.o \
 	src/common/netchan.o \
 	src/common/pmove.o \
+	src/common/rand.o \
 	src/common/szone.o \
 	src/common/zone.o \
 	src/common/command/cmd_execution.o \
diff --git a/src/common/header/common.h b/src/common/header/common.h
index 24f3ad5e..88fba834 100644
--- a/src/common/header/common.h
+++ b/src/common/header/common.h
@@ -757,4 +757,8 @@ void SV_Init (void);
 void SV_Shutdown (char *finalmsg, qboolean reconnect);
 void SV_Frame (int msec);
 
+/* Random number generator */
+int  randk(void);
+void randk_seed(void);
+
 #endif
diff --git a/src/common/rand.c b/src/common/rand.c
new file mode 100644
index 00000000..6a60508f
--- /dev/null
+++ b/src/common/rand.c
@@ -0,0 +1,69 @@
+/*
+ * KISS PRNG (c) 2011 Shinobu
+ *
+ * This file was optained from zuttobenkyou.wordpress.com
+ * and modified by the Yamagi Quake II developers.
+ *
+ * LICENSE: Public domain
+ *
+ * =======================================================================
+ *
+ * KISS PRNG, as devised by Dr. George Marsaglia
+ *
+ * =======================================================================
+ */
+
+#include <stdint.h>
+
+#define QSIZE 0x200000
+#define CNG (cng = 6906969069ULL * cng + 13579)
+#define XS (xs ^= (xs << 13), xs ^= (xs >> 17), xs ^= (xs << 43))
+#define KISS (B64MWC() + CNG + XS)
+
+static uint64_t QARY[QSIZE];
+static int j;
+static uint64_t carry;
+static uint64_t xs;
+static uint64_t cng;
+
+uint64_t
+B64MWC(void)
+{
+	uint64_t t, x;
+
+	j = (j + 1) & (QSIZE - 1);
+	x = QARY[j];
+	t = (x << 28) + carry;
+	carry = (x >> 36) - (t < x);
+	return QARY[j] = t - x;
+}
+
+/* 
+ * Generate a pseudorandom 
+ * signed integer. 
+ */
+int
+randk(void)
+{
+	return (int)KISS;
+}
+ 
+void
+randk_seed(void)
+{
+	uint64_t i;
+
+	/* Seed QARY[] with CNG+XS: */
+	for (i = 0; i < QSIZE; i++)
+	{
+		QARY[i] = CNG + XS;
+	}
+
+	/* Run through several rounds 
+	   to warm up the state */
+	for (i = 0; i < 256; i++)
+	{
+		randk();
+	}
+}
+