From 6df187aea440d1859393675de264a86a4936f9ca Mon Sep 17 00:00:00 2001
From: Moritz Lenz <moritz@faui2k3.org>
Date: Sun, 13 Nov 2011 19:17:46 +0100
Subject: [PATCH] Add set_long and get_long functions

They work on platform-dependent long ints
---
 bn_mp_get_long.c | 39 +++++++++++++++++++++++++++++++++++++++
 bn_mp_set_long.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 tommath.h        |  6 ++++++
 3 files changed, 93 insertions(+)
 create mode 100644 bn_mp_get_long.c
 create mode 100644 bn_mp_set_long.c

diff --git a/bn_mp_get_long.c b/bn_mp_get_long.c
new file mode 100644
index 0000000..1ea6a85
--- /dev/null
+++ b/bn_mp_get_long.c
@@ -0,0 +1,39 @@
+#include <tommath.h>
+#ifdef BN_MP_GET_INT_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis
+ *
+ * LibTomMath is a library that provides multiple-precision
+ * integer arithmetic as well as number theoretic functionality.
+ *
+ * The library was designed directly after the MPI library by
+ * Michael Fromberger but has been written from scratch with
+ * additional optimizations in place.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ *
+ * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
+ */
+
+/* get the lower unsigned long of an mp_int, platform dependent */
+unsigned long mp_get_long(mp_int * a)
+{
+  int i;
+  unsigned long res;
+
+  if (a->used == 0) {
+     return 0;
+  }
+
+  /* get number of digits of the lsb we have to read */
+  i = MIN(a->used,(int)((sizeof(unsigned long)*CHAR_BIT+DIGIT_BIT-1)/DIGIT_BIT))-1;
+
+  /* get most significant digit of result */
+  res = DIGIT(a,i);
+   
+  while (--i >= 0) {
+    res = (res << DIGIT_BIT) | DIGIT(a,i);
+  }
+  return res;
+}
+#endif
diff --git a/bn_mp_set_long.c b/bn_mp_set_long.c
new file mode 100644
index 0000000..7751016
--- /dev/null
+++ b/bn_mp_set_long.c
@@ -0,0 +1,48 @@
+#include <tommath.h>
+#ifdef BN_MP_SET_INT_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis
+ *
+ * LibTomMath is a library that provides multiple-precision
+ * integer arithmetic as well as number theoretic functionality.
+ *
+ * The library was designed directly after the MPI library by
+ * Michael Fromberger but has been written from scratch with
+ * additional optimizations in place.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ *
+ * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
+ */
+
+/* set a platform dependent unsigned long int */
+int mp_set_long (mp_int * a, unsigned long b)
+{
+  int     x, res;
+
+  mp_zero (a);
+  
+  /* set four bits at a time */
+  for (x = 0; x < sizeof(unsigned long) * 2; x++) {
+    /* shift the number up four bits */
+    if ((res = mp_mul_2d (a, 4, a)) != MP_OKAY) {
+      return res;
+    }
+
+    /* OR in the top four bits of the source */
+    a->dp[0] |= (b >> ((sizeof(unsigned long)) * 8 - 4)) & 15;
+
+    /* shift the source up to the next four bits */
+    b <<= 4;
+
+    /* ensure that digits are not clamped off */
+    a->used += 1;
+  }
+  mp_clamp (a);
+  return MP_OKAY;
+}
+#endif
+
+/* $Source$ */
+/* $Revision$ */
+/* $Date$ */
diff --git a/tommath.h b/tommath.h
index 800d4b6..a3faf35 100644
--- a/tommath.h
+++ b/tommath.h
@@ -242,9 +242,15 @@ void mp_set(mp_int *a, mp_digit b);
 /* set a 32-bit const */
 int mp_set_int(mp_int *a, unsigned long b);
 
+/* set a platform dependent unsigned long value */
+int mp_set_long(mp_int *a, unsigned long b);
+
 /* get a 32-bit value */
 unsigned long mp_get_int(mp_int * a);
 
+/* get a platform dependent unsigned long value */
+unsigned long mp_get_long(mp_int * a);
+
 /* initialize and set a digit */
 int mp_init_set (mp_int * a, mp_digit b);