summaryrefslogtreecommitdiffstats
path: root/libtommath/bn_mp_get_int.c
diff options
context:
space:
mode:
Diffstat (limited to 'libtommath/bn_mp_get_int.c')
-rw-r--r--libtommath/bn_mp_get_int.c41
1 files changed, 41 insertions, 0 deletions
diff --git a/libtommath/bn_mp_get_int.c b/libtommath/bn_mp_get_int.c
new file mode 100644
index 0000000..034467b
--- /dev/null
+++ b/libtommath/bn_mp_get_int.c
@@ -0,0 +1,41 @@
+#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@iahu.ca, http://math.libtomcrypt.org
+ */
+
+/* get the lower 32-bits of an mp_int */
+unsigned long mp_get_int(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);
+ }
+
+ /* force result to 32-bits always so it is consistent on non 32-bit platforms */
+ return res & 0xFFFFFFFFUL;
+}
+#endif