pipeline: raspberrypi: rpi_stream: Set invalid buffer to id == 0

At present, the RPiStream buffer ids == -1 indicates an invalid value.
As a simplification, use id == 0 to indicate an invalid value. This
allows for better code readability.

As a consequence of this, use unsigned int for the buffer id values.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/libcamera/pipeline/rpi/common/rpi_stream.cpp

@@ -55,17 +55,17 @@ const BufferMap &Stream::getBuffers() const
 	return bufferMap_;
 }
 
-int Stream::getBufferId(FrameBuffer *buffer) const
+unsigned int Stream::getBufferId(FrameBuffer *buffer) const
 {
 	if (importOnly_)
-		return -1;
+		return 0;
 
 	/* Find the buffer in the map, and return the buffer id. */
 	auto it = std::find_if(bufferMap_.begin(), bufferMap_.end(),
 			       [&buffer](auto const &p) { return p.second == buffer; });
 
 	if (it == bufferMap_.end())
-		return -1;
+		return 0;
 
 	return it->first;
 }
@@ -77,10 +77,10 @@ void Stream::setExternalBuffer(FrameBuffer *buffer)
 
 void Stream::removeExternalBuffer(FrameBuffer *buffer)
 {
-	int id = getBufferId(buffer);
+	unsigned int id = getBufferId(buffer);
 
 	/* Ensure we have this buffer in the stream, and it is marked external. */
-	ASSERT(id != -1 && (id & BufferMask::MaskExternalBuffer));
+	ASSERT(id & BufferMask::MaskExternalBuffer);
 	bufferMap_.erase(id);
 }
 

src/libcamera/pipeline/rpi/common/rpi_stream.h

@@ -58,7 +58,7 @@ public:
 
 	void setExportedBuffers(std::vector<std::unique_ptr<FrameBuffer>> *buffers);
 	const BufferMap &getBuffers() const;
-	int getBufferId(FrameBuffer *buffer) const;
+	unsigned int getBufferId(FrameBuffer *buffer) const;
 
 	void setExternalBuffer(FrameBuffer *buffer);
 	void removeExternalBuffer(FrameBuffer *buffer);
@@ -74,25 +74,25 @@ private:
 	class IdGenerator
 	{
 	public:
-		IdGenerator(int max)
+		IdGenerator(unsigned int max)
 			: max_(max), id_(0)
 		{
 		}
 
-		int get()
+		unsigned int get()
 		{
-			int id;
+			unsigned int id;
 			if (!recycle_.empty()) {
 				id = recycle_.front();
 				recycle_.pop();
 			} else {
-				id = id_++;
+				id = ++id_;
 				ASSERT(id_ <= max_);
 			}
 			return id;
 		}
 
-		void release(int id)
+		void release(unsigned int id)
 		{
 			recycle_.push(id);
 		}
@@ -104,9 +104,9 @@ private:
 		}
 
 	private:
-		int max_;
-		int id_;
-		std::queue<int> recycle_;
+		unsigned int max_;
+		unsigned int id_;
+		std::queue<unsigned int> recycle_;
 	};
 
 	void clearBuffers();

src/libcamera/pipeline/rpi/vc4/raspberrypi.cpp

@@ -1210,7 +1210,7 @@ int PipelineHandlerRPi::queueRequestDevice(Camera *camera, Request *request)
 			continue;
 
 		FrameBuffer *buffer = request->findBuffer(stream);
-		if (buffer && stream->getBufferId(buffer) == -1) {
+		if (buffer && !stream->getBufferId(buffer)) {
 			/*
 			 * This buffer is not recognised, so it must have been allocated
 			 * outside the v4l2 device. Store it in the stream buffer list
@@ -2042,7 +2042,7 @@ void RPiCameraData::unicamBufferDequeue(FrameBuffer *buffer)
 
 	for (RPi::Stream &s : unicam_) {
 		index = s.getBufferId(buffer);
-		if (index != -1) {
+		if (index) {
 			stream = &s;
 			break;
 		}
@@ -2098,7 +2098,7 @@ void RPiCameraData::ispOutputDequeue(FrameBuffer *buffer)
 
 	for (RPi::Stream &s : isp_) {
 		index = s.getBufferId(buffer);
-		if (index != -1) {
+		if (index) {
 			stream = &s;
 			break;
 		}