From ee3eaabc91411905316a5b9ebd132c16987a9769 Mon Sep 17 00:00:00 2001
From: Alan Cox <alan@linux.intel.com>
Date: Mon, 20 Jun 2016 20:02:29 +0100
Subject: [PATCH] drand48: the 48bit random functions

Untested at this point
---
 Library/libs/drand48.c |  26 +++++++++++
 Library/libs/lrand48.c | 100 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 126 insertions(+)
 create mode 100644 Library/libs/drand48.c
 create mode 100644 Library/libs/lrand48.c

diff --git a/Library/libs/drand48.c b/Library/libs/drand48.c
new file mode 100644
index 00000000..1405499a
--- /dev/null
+++ b/Library/libs/drand48.c
@@ -0,0 +1,26 @@
+#include <stdlib.h>
+#include <math.h>
+#include <string.h>
+#include "rand48.h"
+
+double drand48(void)
+{
+  __iteration48();
+  return ldexp((double)__msa48[3], -48) +
+         ldexp((double)__msa48[4], -32) +
+         ldexp((double)__msa48[5], -16);
+}
+
+double erand48(unsigned short s[3])
+{
+  uint16_t b[3];
+  double r;
+
+  memcpy(b, __msa48 + 3, 3 * sizeof(uint16_t));
+  memcpy(__msa48 + 3, s, 3 * sizeof(uint16_t));
+  r = drand48();
+  memcpy(__msa48 + 3, b, 3 * sizeof(uint16_t));
+  return r;
+}
+  
+  
\ No newline at end of file
diff --git a/Library/libs/lrand48.c b/Library/libs/lrand48.c
new file mode 100644
index 00000000..a2e9bcd1
--- /dev/null
+++ b/Library/libs/lrand48.c
@@ -0,0 +1,100 @@
+#include <stdlib.h>
+#include <string.h>
+#include "rand48.h"
+
+static uint16_t msa48_def[4] = { 0xe66d, 0xdeec, 0x0005, 0x330E };
+uint16_t __msa48[7] = {0xe66d, 0xdeec, 0x0005, 0x330E, 0xABCD, 0x1234, 0x000B};
+static uint32_t sum;
+static uint16_t tmp[2];
+static uint16_t msa48_save[3];
+
+static void lmuladd(uint8_t a, uint8_t b)
+{
+  sum += (unsigned long)__msa48[a] * (unsigned long)__msa48[b];
+}
+
+static uint16_t roll(void)
+{
+  uint16_t v = sum;
+  sum >>= 16;
+}
+
+void __iteration48(void)
+{
+  sum = 0;
+  lmuladd(0, 3);
+  sum += (uint32_t)__msa48[6];
+  
+  tmp[0] = roll();
+  
+  lmuladd(0, 4);
+  lmuladd(1, 3);
+  
+  tmp[1] = roll();
+  
+  lmuladd(0, 5);
+  lmuladd(1, 4);
+  lmuladd(2, 3);
+  
+  __msa48[3] = tmp[0];
+  __msa48[4] = tmp[1];
+  __msa48[5] = roll();
+}
+
+void srand48(long seed)
+{
+  __msa48[4] = (uint16_t) seed;
+  __msa48[5] = (uint16_t) (seed >> 16);
+
+  memcpy(__msa48, msa48_def, 4 * sizeof(uint16_t));
+}
+
+void lcong48(unsigned short p[7])
+{
+  memcpy(__msa48, p, 7 * sizeof(uint16_t));
+}
+
+long lrand48(void)
+{
+  __iteration48();
+  return (long)((__msa48[5] >> 1) + (((uint32_t)__msa48[4]) << 15));
+}
+
+long nrand48(unsigned short s[3])
+{
+  uint16_t b[3];
+  long r;
+
+  memcpy(b, __msa48 + 3, 3 * sizeof(uint16_t));
+  memcpy(__msa48 + 3, s, 3 * sizeof(uint16_t));
+  r = lrand48();
+  memcpy(__msa48 + 3, b, 3 * sizeof(uint16_t));
+  return r;
+}
+
+unsigned long mrand48(void)
+{
+  __iteration48();
+  return (unsigned long)((__msa48[5]) + (((uint32_t)__msa48[4]) << 16));
+}
+
+unsigned long jrand48(unsigned short s[3])
+{
+  uint16_t b[3];
+  unsigned long r;
+
+  memcpy(b, __msa48 + 3, 3 * sizeof(uint16_t));
+  memcpy(__msa48 + 3, s, 3 * sizeof(uint16_t));
+  r = mrand48();
+  memcpy(__msa48 + 3, b, 3 * sizeof(uint16_t));
+  return r;
+}
+
+unsigned short *seed48(unsigned short n[7])
+{
+  memcpy(msa48_save, __msa48 + 3, 3 * sizeof(uint16_t));
+  memcpy(__msa48 + 3, n, 3 * sizeof(uint16_t));
+  memcpy(__msa48, msa48_def, 3 * sizeof(uint16_t));
+  return msa48_save;
+}
+
-- 
2.34.1