53 lines
1.2 KiB
C++
53 lines
1.2 KiB
C++
#include <fcntl.h>
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#include <linux/dma-heap.h>
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#include <sys/ioctl.h>
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#include <sys/mman.h>
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#include <unistd.h>
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#include <iostream>
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#include <string>
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class DmaBuffer {
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public:
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int fd;
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void* vaddr; // 虚拟地址（仅供调试或CPU必须介入时使用，如画字）
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size_t size;
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DmaBuffer(size_t size, const std::string& heap_name = "/dev/dma_heap/system") {
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this->size = size;
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this->vaddr = MAP_FAILED;
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this->fd = -1;
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int heap_fd = open(heap_name.c_str(), O_RDONLY | O_CLOEXEC);
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if (heap_fd < 0) {
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perror("Failed to open dma heap");
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return;
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}
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struct dma_heap_allocation_data data = {0};
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data.len = size;
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data.fd_flags = O_RDWR | O_CLOEXEC;
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if (ioctl(heap_fd, DMA_HEAP_IOCTL_ALLOC, &data) < 0) {
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perror("dma heap alloc failed");
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close(heap_fd);
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return;
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}
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this->fd = data.fd;
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close(heap_fd);
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// 如果需要CPU访问（例如写OSD文字），则映射，否则可以不映射
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this->vaddr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, this->fd, 0);
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if (this->vaddr == MAP_FAILED) {
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perror("mmap failed");
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}
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}
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~DmaBuffer() {
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if (vaddr != MAP_FAILED)
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munmap(vaddr, size);
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if (fd >= 0)
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close(fd);
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}
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}; |