1 files changed, 46 insertions, 0 deletions
diff --git a/lib/sat-math.h b/lib/sat-math.h
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+/*
+ * Copyright (c) 2008 Nicira Networks.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef SAT_MATH_H
+#define SAT_MATH_H 1
+
+#include <assert.h>
+#include <limits.h>
+
+/* Saturating addition: overflow yields UINT_MAX. */
+static inline unsigned int
+sat_add(unsigned int x, unsigned int y)
+{
+    return x + y >= x ? x + y : UINT_MAX;
+}
+
+/* Saturating subtraction: underflow yields 0. */
+static inline unsigned int
+sat_sub(unsigned int x, unsigned int y)
+{
+    return x >= y ? x - y : 0;
+}
+
+/* Saturating multiplication: overflow yields UINT_MAX. */
+static inline unsigned int
+sat_mul(unsigned int x, unsigned int y)
+{
+    return (!y ? 0
+            : x <= UINT_MAX / y ? x * y
+            : UINT_MAX);
+}
+
+#endif /* sat-math.h */