Add PrrtTimestamp_cmp method.

prrt/CMakeLists.txt

@@ -15,7 +15,7 @@ add_subdirectory(proto)
 add_subdirectory(util)
 
 add_executable(sender sender.c)
-add_executable(receiver receiver.c ../tests/common.h)
+add_executable(receiver receiver.c)
 
 target_link_libraries(sender LINK_PUBLIC PRRT UTIL ${CMAKE_THREAD_LIBS_INIT})
 target_link_libraries(receiver LINK_PUBLIC PRRT UTIL ${CMAKE_THREAD_LIBS_INIT})

prrt/util/time.c

@@ -21,3 +21,14 @@ struct timespec abstime_from_now(uint32_t wait_time) {
     return deadline;
 }
 
+// < 0: a less than b (b is in the future)
+// > 0: a greater b (b is in the past)
+// == 0: a equal b
+int64_t PrrtTimestamp_cmp(prrtTimestamp_t a, prrtTimestamp_t b) {
+    prrtTimestamp_t diff = (prrtTimestamp_t) (a - b);
+    if (diff < TIMESTAMP_SPACE / 2) {
+        return diff;
+    } else {
+        return ((int64_t)diff) - ((int64_t)(TIMESTAMP_SPACE) + 1);
+    }
+}
\ No newline at end of file

prrt/util/time.h

 #ifndef PRRT_TIME_H
 #define PRRT_TIME_H
+#include "../proto/types/packet.h"
 
 long long timedelta(struct timespec *t1, struct timespec *t2);
 struct timespec abstime_from_now(uint32_t wait_time);
+int64_t PrrtTimestamp_cmp(prrtTimestamp_t a, prrtTimestamp_t b);
 
 #endif //PRRT_TIME_H

tests/CMakeLists.txt

 add_subdirectory(lib/gtest-1.8.0)
 include_directories(SYSTEM ${gtest_SOURCE_DIR}/include ${gtest_SOURCE_DIR})
 
-add_executable(prrtTests common.h bitmap_tests.cpp receptionTable_tests.cpp delivered_packet_table_tests.cpp bptree_tests.cpp PrrtBlock_tests.cpp)
+add_executable(prrtTests common.h util_tests.cpp bitmap_tests.cpp receptionTable_tests.cpp delivered_packet_table_tests.cpp bptree_tests.cpp PrrtBlock_tests.cpp)
 target_link_libraries(prrtTests LINK_PUBLIC gtest PRRT UTIL gtest_main)
\ No newline at end of file

tests/util_tests.cpp

+#include "common.h"
+
+extern "C" {
+#include "prrt/util/time.h"
+}
+
+class UtilTests : public ::testing::Test {
+protected:
+    virtual void SetUp()
+    {
+
+    }
+
+    virtual void TearDown()
+    {
+
+    }
+
+
+};
+
+TEST_F(UtilTests, Timestamps)
+{
+    prrtTimestamp_t a = 5;
+    prrtTimestamp_t b = 47;
+    prrtTimestamp_t c = 4294967295;
+
+    ASSERT_EQ(PrrtTimestamp_cmp(a,b), -42);
+    ASSERT_EQ(PrrtTimestamp_cmp(b,a), 42);
+
+    ASSERT_EQ(PrrtTimestamp_cmp(c,a), -6);
+    ASSERT_EQ(PrrtTimestamp_cmp(a,c), 6);
+}
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