1 files changed, 51 insertions, 0 deletions
diff --git a/contrib/bearssl/src/int/i32_sub.c b/contrib/bearssl/src/int/i32_sub.c
new file mode 100644
index 000000000000..9c50023824a3
--- /dev/null
+++ b/contrib/bearssl/src/int/i32_sub.c
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining 
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be 
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "inner.h"
+
+/* see inner.h */
+uint32_t
+br_i32_sub(uint32_t *a, const uint32_t *b, uint32_t ctl)
+{
+	uint32_t cc;
+	size_t u, m;
+
+	cc = 0;
+	m = (a[0] + 63) >> 5;
+	for (u = 1; u < m; u ++) {
+		uint32_t aw, bw, naw;
+
+		aw = a[u];
+		bw = b[u];
+		naw = aw - bw - cc;
+
+		/*
+		 * Carry is 1 if naw > aw. Carry is 1 also if naw == aw
+		 * AND the carry was already 1.
+		 */
+		cc = (cc & EQ(naw, aw)) | GT(naw, aw);
+		a[u] = MUX(ctl, naw, aw);
+	}
+	return cc;
+}