lib_mem_dmabuf

Overview

lib_mem_dmabuf is a library for access and interact with Linux DMA buffer.

Feature highlights

• Alloc and destroy DMA buffer

• Return file descriptor (fd) associated with DMA buffer

• DMA buffer synchronization operation

• Auto release DMA buffer and fd when leave code scope

• Register DMA buffer release callback

Quickstart

1. Add dependencies in your package.xml

   <depend>lib_mem_dmabuf</depend>
   

2. Use ament_cmake_auto to find dependencies in your CMakeLists.txt

   find_package(ament_cmake_auto REQUIRED)
   ament_auto_find_build_dependencies()
   

3. Using lib_mem_dmabuf to alloc DMA buffer

   #include "lib_mem_dmabuf/dmabuf.hpp"
   
   // alloc dmabuf with size and DMA heap name
   auto buf = lib_mem_dmabuf::DmaBuffer::alloc(size, "/dev/dma_heap/system");
   
   // get fd of buffer
   std::cout << "fd: " << buf->fd() << std::endl;
   
   // get CPU accessable address
   if (buf->map()) {
     std::cout << "CPU address: " << buf->addr() << std::endl;
     // read / write buffer
     // ...
   }
   
   // buf will auto release when leave scope
   

API

Function	Parameters	Return Value	Description
DmaBuffer::DmaBuffer(int fd, std::size_t size)	fd: dmabuf fd, size: dmabuf size		Constructor for DmaBuffer class
static std::shared_ptr<DmaBuffer> alloc(std::size_t size, const std::string& heap_name)	size: buffer size (bytes), heap_name: dmabuf heap name	Allocated buffer pointer	Alloc dmabuf with size and heap name
bool DmaBuffer::release()			Release dmabuf
bool DmaBuffer::map()			Description
bool DmaBuffer::unmap()			Description
bool DmaBuffer::sync_start()			Description
bool DmaBuffer::sync_end()			Description
bool DmaBuffer::set_auto_release(bool auto_release)	auto_release: whether to auto release fd when Dmabuf object destroy		Set auto release dmabuf fd when destroy
void DmaBuffer::set_destroy_callback( std::function<void(std::shared_ptr<DmaBuffer>)> cb);	cb: callback function when dmabuf destroy		Set destroys callback function
bool DmaBuffer::set_data(void* data, std::size_t size, std::size_t offset = 0)	data: data be saved, size: data size, offset: offset to dmabuf address		Set data into dmabuf
int DmaBuffer::fd() const		Dmabuf file descriptor	Get dmabuf fd
int DmaBuffer::size() const		Dmabuf size	Get dmabuf size
void* DmaBuffer::addr()		Dmabuf CPU mapped address	Get dmabuf CPU memory mapped address