This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / crypto / mpi / mpi-gcd.c

diff --git a/crypto/mpi/mpi-gcd.c b/crypto/mpi/mpi-gcd.c
new file mode 100644 (file)
index 0000000..2841b9f
--- /dev/null
+++ b/crypto/mpi/mpi-gcd.c
@@ -0,0 +1,60 @@
+/* mpi-gcd.c  -  MPI functions
+ * Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#include "mpi-internal.h"
+
+/****************
+ * Find the greatest common divisor G of A and B.
+ * Return: true if this 1, false in all other cases
+ */
+int
+mpi_gcd( MPI g, const MPI xa, const MPI xb )
+{
+    MPI a = NULL, b = NULL;
+
+    if (mpi_copy(&a, xa) < 0)
+           goto nomem;
+
+    if (mpi_copy(&b, xb) < 0)
+           goto nomem;
+
+    /* TAOCP Vol II, 4.5.2, Algorithm A */
+    a->sign = 0;
+    b->sign = 0;
+    while( mpi_cmp_ui( b, 0 ) ) {
+           if (mpi_fdiv_r( g, a, b ) < 0) /* g used as temorary variable */
+                   goto nomem;
+           if (mpi_set(a,b) < 0)
+                   goto nomem;
+           if (mpi_set(b,g) < 0)
+                   goto nomem;
+    }
+    if (mpi_set(g, a) < 0)
+           goto nomem;
+
+    mpi_free(a);
+    mpi_free(b);
+    return !mpi_cmp_ui( g, 1);
+
+ nomem:
+    mpi_free(a);
+    mpi_free(b);
+    return -ENOMEM;
+}