1 files changed, 144 insertions, 0 deletions
diff --git a/lib/libmpa/mpa_modulus.c b/lib/libmpa/mpa_modulus.c
new file mode 100644
index 0000000..5942942
--- /dev/null
+++ b/lib/libmpa/mpa_modulus.c
@@ -0,0 +1,144 @@
+/*
+ * Copyright (c) 2014, STMicroelectronics International N.V.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "mpa.h"
+
+/*************************************************************
+ *
+ *   LIB FUNCTIONS
+ *
+ *************************************************************/
+
+/*------------------------------------------------------------
+ *
+ *  mpa_mod
+ *
+ */
+void mpa_mod(mpanum dest, const mpanum op, const mpanum n, mpa_scratch_mem pool)
+{
+	mpa_div(NULL, dest, op, n, pool);
+}
+
+/*------------------------------------------------------------
+ *
+ *  mpa_add_mod
+ *
+ */
+void mpa_add_mod(mpanum dest,
+		const mpanum op1,
+		const mpanum op2, const mpanum n, mpa_scratch_mem pool)
+{
+	mpanum tmp_dest;
+
+	mpa_alloc_static_temp_var(&tmp_dest, pool);
+
+	mpa_add(tmp_dest, op1, op2, pool);
+	mpa_div(NULL, dest, tmp_dest, n, pool);
+
+	mpa_free_static_temp_var(&tmp_dest, pool);
+}
+
+/*------------------------------------------------------------
+ *
+ *  mpa_sub_mod
+ *
+ */
+void mpa_sub_mod(mpanum dest,
+		const mpanum op1,
+		const mpanum op2, const mpanum n, mpa_scratch_mem pool)
+{
+	mpanum tmp_dest;
+
+	mpa_alloc_static_temp_var(&tmp_dest, pool);
+
+	mpa_sub(tmp_dest, op1, op2, pool);
+	mpa_div(NULL, dest, tmp_dest, n, pool);
+
+	mpa_free_static_temp_var(&tmp_dest, pool);
+}
+
+/*------------------------------------------------------------
+ *
+ *  mpa_mul_mod
+ *
+ */
+void mpa_mul_mod(mpanum dest,
+		const mpanum op1,
+		const mpanum op2, const mpanum n, mpa_scratch_mem pool)
+{
+	mpanum tmp_dest;
+
+	mpa_alloc_static_temp_var(&tmp_dest, pool);
+
+	mpa_mul(tmp_dest, op1, op2, pool);
+	mpa_div(NULL, dest, tmp_dest, n, pool);
+
+	mpa_free_static_temp_var(&tmp_dest, pool);
+}
+
+/*------------------------------------------------------------
+ *
+ *  mpa_inv_mod
+ *
+ */
+int mpa_inv_mod(mpanum dest,
+	       const mpanum op, const mpanum n, mpa_scratch_mem pool)
+{
+	mpanum gcd;
+	mpanum tmp_dest;
+	int mem_marker;
+	int res;
+
+	if (mpa_cmp_short(op, 1) == 0) {
+		mpa_set_S32(dest, 1);
+		return 0;
+	}
+
+	mem_marker = (dest == op);
+	if (mem_marker)
+		mpa_alloc_static_temp_var(&tmp_dest, pool);
+	else
+		tmp_dest = dest;
+
+	mpa_alloc_static_temp_var(&gcd, pool);
+	/* The function mpa_extended_gcd behaves badly if tmp_dest = op */
+	mpa_extended_gcd(gcd, tmp_dest, NULL, op, n, pool);
+	res = mpa_cmp_short(gcd, 1);
+
+	if (mem_marker) {
+		mpa_copy(dest, tmp_dest);
+		mpa_free_static_temp_var(&tmp_dest, pool);
+	}
+
+	mpa_free_static_temp_var(&gcd, pool);
+	if (res == 0) {
+		while (mpa_cmp_short(dest, 0) < 0)
+			mpa_add(dest, dest, n, pool);
+		return 0;
+	} else {
+		return -1;
+	}
+}