3.m.offset中,从将要mapping 的device memory头到数据头的offset. 4.length中,填充当前Buffer长度。 5。其它的Field有可能设置,也有可能不被设置。 这样,mmap()想要有的信息就全了。而mmap()之后,Device Driver 申请的或者Device Memory就能映射到用户空间。数据就可以被应用
3.m.offset中,从将要mapping 的device memory头到数据头的offset. 4. length 中,填充当前Buffer长度。 5.其它的Field有可能设置,也有可能不被设置。 这样,mmap()想要有的信息就全了。而mmap()之后,Device Driver 申请的或者Device Memory就能映射到用户空间。数据就可以被应用程序使用了。这才是ioctl-VIDIOC_QUERY...
26.size_t length; 27.}; 28. 29.static char *dev_name1; 30.static char *dev_name2; 31.static int fd1 = -1; 32.static int fd2 = -1; 33. 34.struct buffer *buffers; 35.static unsigned int n_buffers; 36.static char *fb_buffer; 37.static unsigned long screensize; 38. 39.stati...
#define I2C_M_NO_RD_ACK 0x0800 /* if I2C_FUNC_PROTOCOL_MANGLING */ #define I2C_M_RECV_LEN 0x0400 /* length will be first received byte */ __u16 len; /* msg length */ __u8 *buf; /* pointer to msg data */ }; 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 1...
4.length中,填充当前Buffer长度。 5。其它的Field有可能设置,也有可能不被设置。 这样,mmap()想要有的信息就全了。而mmap()之后,Device Driver 申请的或者Device Memory就能映射到用户空间。数据就可以被应用程序使用了。这才是ioctl-VIDIOC_QUERYBUF的关键作用。
size_t length; }; static char *dev_name1; static char *dev_name2; static int fd1 = -1; static int fd2 = -1; struct buffer *buffers; static unsigned int n_buffers; static char *fb_buffer; static unsigned long screensize; static char *yuv_buffer; ...
size_t length; }; static char *dev_name1; static char *dev_name2; static int fd1 = -1; static int fd2 = -1; struct buffer *buffers; static unsigned int n_buffers; static char *fb_buffer; static unsigned long screensize; static char *yuv_buffer; ...
size_t length; }; static char *dev_name1; static char *dev_name2; static int fd1 = -1; static int fd2 = -1; struct buffer *buffers; static unsigned int n_buffers; static char *fb_buffer; static unsigned long screensize; static char *yuv_buffer; ...
size_t length; }; static char *dev_name1; static char *dev_name2; static int fd1 = -1; static int fd2 = -1; struct buffer *buffers; static unsigned int n_buffers; static char *fb_buffer; static unsigned long screensize; static char *yuv_buffer; ...
__u32 length; __u32 reserved2; __u32 reserved; };struct vb2_buffer { structvb2_queue*vb2_queue;---当前缓存所在的缓存队列。 unsigned int index;---当前buffer在vb2_queue上的序号,vb2_queue->bufs[index]可以找到此缓存。 unsigned int type;---v4l2_buf_type类型,用户空间设定内存...