#include <fcntl.h>
#include <linux/dma-heap.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <unistd.h>

#include <iostream>
#include <string>

class DmaBuffer {
public:
	int fd;
	void* vaddr;  // 虚拟地址（仅供调试或CPU必须介入时使用，如画字）
	size_t size;

	DmaBuffer(size_t size, const std::string& heap_name = "/dev/dma_heap/system") {
		this->size = size;
		this->vaddr = MAP_FAILED;
		this->fd = -1;

		int heap_fd = open(heap_name.c_str(), O_RDONLY | O_CLOEXEC);
		if (heap_fd < 0) {
			perror("Failed to open dma heap");
			return;
		}

		struct dma_heap_allocation_data data = {0};
		data.len = size;
		data.fd_flags = O_RDWR | O_CLOEXEC;

		if (ioctl(heap_fd, DMA_HEAP_IOCTL_ALLOC, &data) < 0) {
			perror("dma heap alloc failed");
			close(heap_fd);
			return;
		}

		this->fd = data.fd;
		close(heap_fd);

		// 如果需要CPU访问（例如写OSD文字），则映射，否则可以不映射
		this->vaddr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, this->fd, 0);
		if (this->vaddr == MAP_FAILED) {
			perror("mmap failed");
		}
	}

	~DmaBuffer() {
		if (vaddr != MAP_FAILED)
			munmap(vaddr, size);
		if (fd >= 0)
			close(fd);
	}
};