util/CircularBuffer: new buffer class

1 files changed, 141 insertions, 0 deletions

diff --git a/test/TestCircularBuffer.hxx b/test/TestCircularBuffer.hxx
new file mode 100644
index 000000000..e4285484b
--- /dev/null
+++ b/test/TestCircularBuffer.hxx
@@ -0,0 +1,141 @@
+/*
+ * Unit tests for class CircularBuffer.
+ */
+
+#include "config.h"
+#include "util/CircularBuffer.hxx"
+
+#include <cppunit/TestFixture.h>
+#include <cppunit/extensions/TestFactoryRegistry.h>
+#include <cppunit/ui/text/TestRunner.h>
+#include <cppunit/extensions/HelperMacros.h>
+
+#include <string.h>
+#include <stdlib.h>
+
+class TestCircularBuffer : public CppUnit::TestFixture {
+	CPPUNIT_TEST_SUITE(TestCircularBuffer);
+	CPPUNIT_TEST(TestIt);
+	CPPUNIT_TEST_SUITE_END();
+
+public:
+	void TestIt() {
+		static size_t N = 8;
+		int data[N];
+		CircularBuffer<int> buffer(data, N);
+
+		/* '.' = empty; 'O' = occupied; 'X' = blocked */
+
+		/* checks on empty buffer */
+		/* [.......X] */
+		CPPUNIT_ASSERT_EQUAL(true, buffer.IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+		CPPUNIT_ASSERT_EQUAL(true, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Write().data);
+		CPPUNIT_ASSERT_EQUAL(size_t(7), buffer.Write().size);
+
+		/* append one element */
+		/* [O......X] */
+		buffer.Append(1);
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(1), buffer.Read().size);
+		CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Read().data);
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(&data[1], buffer.Write().data);
+		CPPUNIT_ASSERT_EQUAL(size_t(6), buffer.Write().size);
+
+		/* append 6 elements, buffer is now full */
+		/* [OOOOOOOX] */
+		buffer.Append(6);
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(true, buffer.IsFull());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(7), buffer.Read().size);
+		CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Read().data);
+		CPPUNIT_ASSERT_EQUAL(true, buffer.Write().IsEmpty());
+
+		/* consume [0]; can append one at [7] */
+		/* [XOOOOOO.] */
+		buffer.Consume(1);
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(6), buffer.Read().size);
+		CPPUNIT_ASSERT_EQUAL(&data[1], buffer.Read().data);
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(&data[7], buffer.Write().data);
+		CPPUNIT_ASSERT_EQUAL(size_t(1), buffer.Write().size);
+
+		/* append one element; [0] is still empty but cannot
+		   be written to because head==1 */
+		/* [XOOOOOOO] */
+		buffer.Append(1);
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(true, buffer.IsFull());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(7), buffer.Read().size);
+		CPPUNIT_ASSERT_EQUAL(&data[1], buffer.Read().data);
+		CPPUNIT_ASSERT_EQUAL(true, buffer.Write().IsEmpty());
+
+		/* consume [1..3]; can append [0..2] */
+		/* [...XOOOO] */
+		buffer.Consume(3);
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(4), buffer.Read().size);
+		CPPUNIT_ASSERT_EQUAL(&data[4], buffer.Read().data);
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Write().data);
+		CPPUNIT_ASSERT_EQUAL(size_t(3), buffer.Write().size);
+
+		/* append [0..1] */
+		/* [OO.XOOOO] */
+		buffer.Append(2);
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(4), buffer.Read().size);
+		CPPUNIT_ASSERT_EQUAL(&data[4], buffer.Read().data);
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(&data[2], buffer.Write().data);
+		CPPUNIT_ASSERT_EQUAL(size_t(1), buffer.Write().size);
+
+		/* append [2] */
+		/* [OOOXOOOO] */
+		buffer.Append(1);
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(true, buffer.IsFull());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(4), buffer.Read().size);
+		CPPUNIT_ASSERT_EQUAL(&data[4], buffer.Read().data);
+		CPPUNIT_ASSERT_EQUAL(true, buffer.Write().IsEmpty());
+
+		/* consume [4..7] */
+		/* [OOO....X] */
+		buffer.Consume(4);
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(3), buffer.Read().size);
+		CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Read().data);
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(&data[3], buffer.Write().data);
+		CPPUNIT_ASSERT_EQUAL(size_t(4), buffer.Write().size);
+
+		/* consume [0..2]; after that, we can only write 5,
+		   because the CircularBuffer class doesn't have
+		   special code to rewind/reset an empty buffer */
+		/* [..X.....] */
+		buffer.Consume(3);
+		CPPUNIT_ASSERT_EQUAL(true, buffer.IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+		CPPUNIT_ASSERT_EQUAL(true, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(&data[3], buffer.Write().data);
+		CPPUNIT_ASSERT_EQUAL(size_t(5), buffer.Write().size);
+	}
+};