[libcamera-devel] [PATCH] libcamera: framebuffer: Return plane begin address by MappedBuffer::maps()

[Hirokazu Honda]

MappedBuffer::maps() returns std::vector<MappedBuffer::Plane>.
Plane has the address, but the address points the beginning of the
buffer containing the plane.
This makes the Plane point the beginning of the plane. So
MappedBuffer::maps()[i].data() returns the address of i-th plane.

Signed-off-by: Hirokazu Honda <hiroh at chromium.org>
---
 include/libcamera/internal/framebuffer.h |  1 +
 src/libcamera/framebuffer.cpp            | 41 +++++++++++++++++-------
 2 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/include/libcamera/internal/framebuffer.h b/include/libcamera/internal/framebuffer.h
index 8c187adf..2eb3b7c9 100644
--- a/include/libcamera/internal/framebuffer.h
+++ b/include/libcamera/internal/framebuffer.h
@@ -36,6 +36,7 @@ protected:
 
 	int error_;
 	std::vector<Plane> maps_;
+	std::vector<Plane> chunks_;
 
 private:
 	LIBCAMERA_DISABLE_COPY(MappedBuffer)
diff --git a/src/libcamera/framebuffer.cpp b/src/libcamera/framebuffer.cpp
index a59e93fb..8231c1df 100644
--- a/src/libcamera/framebuffer.cpp
+++ b/src/libcamera/framebuffer.cpp
@@ -310,6 +310,7 @@ MappedBuffer &MappedBuffer::operator=(MappedBuffer &&other)
 {
 	error_ = other.error_;
 	maps_ = std::move(other.maps_);
+	chunks_ = std::move(other.chunks_);
 	other.error_ = -ENOENT;
 
 	return *this;
@@ -317,8 +318,8 @@ MappedBuffer &MappedBuffer::operator=(MappedBuffer &&other)
 
 MappedBuffer::~MappedBuffer()
 {
-	for (Plane &map : maps_)
-		munmap(map.data(), map.size());
+	for (Plane &chunk : chunks_)
+		munmap(chunk.data(), chunk.size());
 }
 
 /**
@@ -381,18 +382,36 @@ MappedBuffer::~MappedBuffer()
  */
 MappedFrameBuffer::MappedFrameBuffer(const FrameBuffer *buffer, int flags)
 {
+	if (buffer->planes().empty())
+		return;
 	maps_.reserve(buffer->planes().size());
 
+	/*
+	 * Below assumes planes are in the same buffer and planes are
+	 * consecutive.
+	 * \todo remove this assumption.
+	 */
+	const int fd = buffer->planes()[0].fd.fd();
+	const off_t length = lseek(fd, 0, SEEK_END);
+	if (length < 0) {
+		error_ = -errno;
+		LOG(Buffer, Error) << "Failed to lseek buffer";
+		return;
+	}
+
+	void *address = mmap(nullptr, length, flags, MAP_SHARED, fd, 0);
+	if (address == MAP_FAILED) {
+		error_ = -errno;
+		LOG(Buffer, Error) << "Failed to mmap plane";
+		return;
+	}
+	chunks_ = { MappedBuffer::Plane(static_cast<uint8_t *>(address),
+					static_cast<size_t>(length)) };
+	size_t offset = 0;
 	for (const FrameBuffer::Plane &plane : buffer->planes()) {
-		void *address = mmap(nullptr, plane.length, flags,
-				     MAP_SHARED, plane.fd.fd(), 0);
-		if (address == MAP_FAILED) {
-			error_ = -errno;
-			LOG(Buffer, Error) << "Failed to mmap plane";
-			break;
-		}
-
-		maps_.emplace_back(static_cast<uint8_t *>(address), plane.length);
+		maps_.emplace_back(static_cast<uint8_t *>(address) + offset,
+				   plane.length);
+		offset += plane.length;
 	}
 }
 
-- 
2.32.0.554.ge1b32706d8-goog