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authorMatthieu Patou <mat@matws.net>2010-08-15 18:31:28 +0400
committerAndrew Bartlett <abartlet@samba.org>2010-10-03 01:15:04 +0000
commitab6e3fce040f9ad27cbce44e9038a24f15b601c8 (patch)
treeab99a431c9610927b5d0d26335d2712b509fd6dc /source4/heimdal/lib/hcrypto/libtommath/bn_mp_reduce_2k.c
parent197a1514d62494cc8b862d169c841a26e04b8925 (diff)
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s4:heimdal: import lorikeet-heimdal-201009250123 (commit 42cabfb5b683dbcb97d583c397b897507689e382)
I based this on Matthieu's import of lorikeet-heimdal, and then updated it to this commit. Andrew Bartlett
Diffstat (limited to 'source4/heimdal/lib/hcrypto/libtommath/bn_mp_reduce_2k.c')
-rw-r--r--source4/heimdal/lib/hcrypto/libtommath/bn_mp_reduce_2k.c61
1 files changed, 61 insertions, 0 deletions
diff --git a/source4/heimdal/lib/hcrypto/libtommath/bn_mp_reduce_2k.c b/source4/heimdal/lib/hcrypto/libtommath/bn_mp_reduce_2k.c
new file mode 100644
index 0000000000..d9620c221c
--- /dev/null
+++ b/source4/heimdal/lib/hcrypto/libtommath/bn_mp_reduce_2k.c
@@ -0,0 +1,61 @@
+#include <tommath.h>
+#ifdef BN_MP_REDUCE_2K_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
+ */
+
+/* reduces a modulo n where n is of the form 2**p - d */
+int mp_reduce_2k(mp_int *a, mp_int *n, mp_digit d)
+{
+ mp_int q;
+ int p, res;
+
+ if ((res = mp_init(&q)) != MP_OKAY) {
+ return res;
+ }
+
+ p = mp_count_bits(n);
+top:
+ /* q = a/2**p, a = a mod 2**p */
+ if ((res = mp_div_2d(a, p, &q, a)) != MP_OKAY) {
+ goto ERR;
+ }
+
+ if (d != 1) {
+ /* q = q * d */
+ if ((res = mp_mul_d(&q, d, &q)) != MP_OKAY) {
+ goto ERR;
+ }
+ }
+
+ /* a = a + q */
+ if ((res = s_mp_add(a, &q, a)) != MP_OKAY) {
+ goto ERR;
+ }
+
+ if (mp_cmp_mag(a, n) != MP_LT) {
+ s_mp_sub(a, n, a);
+ goto top;
+ }
+
+ERR:
+ mp_clear(&q);
+ return res;
+}
+
+#endif
+
+/* $Source: /cvs/libtom/libtommath/bn_mp_reduce_2k.c,v $ */
+/* $Revision: 1.4 $ */
+/* $Date: 2006/12/28 01:25:13 $ */