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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2019, Google Inc.
*
* framebuffer_allocator.cpp - FrameBuffer allocator
*/
#include <libcamera/framebuffer_allocator.h>
#include <errno.h>
#include <libcamera/buffer.h>
#include <libcamera/camera.h>
#include <libcamera/stream.h>
#include "libcamera/internal/log.h"
#include "libcamera/internal/pipeline_handler.h"
/**
* \file framebuffer_allocator.h
* \brief FrameBuffer allocator
*/
namespace libcamera {
LOG_DEFINE_CATEGORY(Allocator)
/**
* \class FrameBufferAllocator
* \brief FrameBuffer allocator for applications
*
* The libcamera API is designed to consume buffers provided by applications as
* FrameBuffer instances. This makes libcamera a user of buffers exported by
* other devices (such as displays or video encoders), or allocated from an
* external allocator (such as ION on Android platforms). In some situations,
* applications do not have any means to allocate or get hold of suitable
* buffers, for instance when no other device is involved, on Linux platforms
* that lack a centralized allocator. The FrameBufferAllocator class provides a
* buffer allocator that can be used in these situations.
*
* Applications create a framebuffer allocator for a Camera, and use it to
* allocate buffers for streams of a CameraConfiguration with allocate(). They
* control which streams to allocate buffers for, and can thus use external
* buffers for a subset of the streams if desired.
*
* Buffers are deleted for a stream with free(), and destroying the allocator
* automatically deletes all allocated buffers. Applications own the buffers
* allocated by the FrameBufferAllocator and are responsible for ensuring the
* buffers are not deleted while they are in use (part of a Request that has
* been queued and hasn't completed yet).
*
* Usage of the FrameBufferAllocator is optional, if all buffers for a camera
* are provided externally applications shall not use this class.
*/
/**
* \brief Construct a FrameBufferAllocator serving a camera
* \param[in] camera The camera
*/
FrameBufferAllocator::FrameBufferAllocator(std::shared_ptr<Camera> camera)
: camera_(camera)
{
}
FrameBufferAllocator::~FrameBufferAllocator()
{
buffers_.clear();
}
/**
* \brief Allocate buffers for a configured stream
* \param[in] stream The stream to allocate buffers for
*
* Allocate buffers suitable for capturing frames from the \a stream. The Camera
* shall have been previously configured with Camera::configure() and shall be
* stopped, and the stream shall be part of the active camera configuration.
*
* Upon successful allocation, the allocated buffers can be retrieved with the
* buffers() method.
*
* \return The number of allocated buffers on success or a negative error code
* otherwise
* \retval -EACCES The camera is not in a state where buffers can be allocated
* \retval -EINVAL The \a stream does not belong to the camera or the stream is
* not part of the active camera configuration
* \retval -EBUSY Buffers are already allocated for the \a stream
*/
int FrameBufferAllocator::allocate(Stream *stream)
{
if (buffers_.count(stream)) {
LOG(Allocator, Error) << "Buffers already allocated for stream";
return -EBUSY;
}
int ret = camera_->exportFrameBuffers(stream, &buffers_[stream]);
if (ret == -EINVAL)
LOG(Allocator, Error)
<< "Stream is not part of " << camera_->name()
<< " active configuration";
return ret;
}
/**
* \brief Free buffers previously allocated for a \a stream
* \param[in] stream The stream
*
* Free buffers allocated with allocate().
*
* This invalidates the buffers returned by buffers().
*
* \return 0 on success or a negative error code otherwise
* \retval -EACCES The camera is not in a state where buffers can be freed
* \retval -EINVAL The allocator do not handle the \a stream
*/
int FrameBufferAllocator::free(Stream *stream)
{
auto iter = buffers_.find(stream);
if (iter == buffers_.end())
return -EINVAL;
std::vector<std::unique_ptr<FrameBuffer>> &buffers = iter->second;
buffers.clear();
buffers_.erase(iter);
return 0;
}
/**
* \fn FrameBufferAllocator::allocated()
* \brief Check if the allocator has allocated buffers for any stream
* \return True if the allocator has allocated buffers for one or more
* streams, false otherwise
*/
/**
* \brief Retrieve the buffers allocated for a \a stream
* \param[in] stream The stream to retrieve buffers for
*
* This method shall only be called after successfully allocating buffers for
* \a stream with allocate(). The returned buffers are valid until free() is
* called for the same stream or the FrameBufferAllocator instance is destroyed.
*
* \return The buffers allocated for the \a stream
*/
const std::vector<std::unique_ptr<FrameBuffer>> &
FrameBufferAllocator::buffers(Stream *stream) const
{
static const std::vector<std::unique_ptr<FrameBuffer>> empty;
auto iter = buffers_.find(stream);
if (iter == buffers_.end())
return empty;
return iter->second;
}
} /* namespace libcamera */
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