New header for saturating arithmetic.

diff --git a/include/Makefile.am b/include/Makefile.am
index 4f0a46562a4f313476f8faef252fa5822c870339..5af741e79dfea262e3bba71dcbd5bfeca762470f 100644 (file)
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -26,6 +26,7 @@ noinst_HEADERS = \
        queue.h \
        random.h \
        rconn.h \
+       sat-math.h \
        socket-util.h \
        type-props.h \
        timeval.h \

diff --git a/include/sat-math.h b/include/sat-math.h
new file mode 100644 (file)
index 0000000..43dae48
--- /dev/null
+++ b/include/sat-math.h
@@ -0,0 +1,63 @@
+/* Copyright (c) 2008 The Board of Trustees of The Leland Stanford
+ * Junior University
+ *
+ * We are making the OpenFlow specification and associated documentation
+ * (Software) available for public use and benefit with the expectation
+ * that others will use, modify and enhance the Software and contribute
+ * those enhancements back to the community. However, since we would
+ * like to make the Software available for broadest use, with as few
+ * restrictions as possible permission is hereby granted, free of
+ * charge, to any person obtaining a copy of this Software to deal in
+ * the Software under the copyrights 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.
+ *
+ * The name and trademarks of copyright holder(s) may NOT be used in
+ * advertising or publicity pertaining to the Software or any
+ * derivatives without specific, written prior permission.
+ */
+
+#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 */

diff --git a/lib/dhcp-client.c b/lib/dhcp-client.c
index 9df0c6c6c0bbb3b2a912c39e7dc913e9228daa48..c05b6149364329740211a915ee80d1ae2c78a0d3 100644 (file)
--- a/lib/dhcp-client.c
+++ b/lib/dhcp-client.c
@@ -51,6 +51,7 @@
 #include "netdev.h"
 #include "ofp-print.h"
 #include "poll-loop.h"
+#include "sat-math.h"
 #include "timeval.h"
 
 #define THIS_MODULE VLM_dhcp_client
@@ -140,9 +141,6 @@ static unsigned int calc_t2(unsigned int lease);
 static unsigned int calc_t1(unsigned int lease, unsigned int t2);
 
 static unsigned int clamp(unsigned int x, unsigned int min, unsigned int max);
-static unsigned int sat_add(unsigned int x, unsigned int y);
-static unsigned int sat_sub(unsigned int x, unsigned int y);
-static unsigned int sat_mul(unsigned int x, unsigned int y);
 
 /* Creates a new DHCP client to configure the network device 'netdev_name'
  * (e.g. "eth0").
@@ -1013,25 +1011,6 @@ fuzz(unsigned int x, int max_fuzz)
     return fuzz >= 0 ? (y >= x ? y : UINT_MAX) : (y <= x ? y : 0);
 }
 
-static unsigned int
-sat_add(unsigned int x, unsigned int y)
-{
-    return x + y >= x ? x + y : UINT_MAX;
-}
-
-static unsigned int
-sat_sub(unsigned int x, unsigned int y)
-{
-    return x >= y ? x - y : 0;
-}
-
-static unsigned int
-sat_mul(unsigned int x, unsigned int y)
-{
-    assert(y);
-    return x <= UINT_MAX / y ? x * y : UINT_MAX;
-}
-
 static unsigned int
 clamp(unsigned int x, unsigned int min, unsigned int max)
 {

diff --git a/lib/rconn.c b/lib/rconn.c
index 6365a46b89e1eac0677b32ad1e5ffa0892837cc7..ee995e499d7ec80310687fbb12d0cd071e045582 100644 (file)
--- a/lib/rconn.c
+++ b/lib/rconn.c
@@ -41,6 +41,7 @@
 #include "buffer.h"
 #include "poll-loop.h"
 #include "ofp-print.h"
+#include "sat-math.h"
 #include "timeval.h"
 #include "util.h"
 #include "vconn.h"
@@ -115,9 +116,6 @@ struct rconn {
     int probe_interval;         /* Secs of inactivity before sending probe. */
 };
 
-static unsigned int sat_add(unsigned int x, unsigned int y);
-static unsigned int sat_sub(unsigned int x, unsigned int y);
-static unsigned int sat_mul(unsigned int x, unsigned int y);
 static unsigned int elapsed_in_this_state(const struct rconn *);
 static unsigned int timeout(const struct rconn *);
 static bool timed_out(const struct rconn *);
@@ -745,25 +743,6 @@ state_transition(struct rconn *rc, enum state state)
     rc->state_entered = time_now();
 }
 
-static unsigned int
-sat_add(unsigned int x, unsigned int y)
-{
-    return x + y >= x ? x + y : UINT_MAX;
-}
-
-static unsigned int
-sat_sub(unsigned int x, unsigned int y)
-{
-    return x >= y ? x - y : 0;
-}
-
-static unsigned int
-sat_mul(unsigned int x, unsigned int y)
-{
-    assert(y);
-    return x <= UINT_MAX / y ? x * y : UINT_MAX;
-}
-
 static void
 question_connectivity(struct rconn *rc) 
 {