大家看看这是什么宏？？？
#define VIDIOCGCAP _IOR('v',1,struct video_capability) /* Get capabilities */#define VIDIOCGCHAN _IOWR('v',2,struct video_channel) /* Get channel info (sources) */
#define VIDIOCSCHAN _IOW('v',3,struct video_channel) /* Set channel */
#define VIDIOCGTUNER _IOWR('v',4,struct video_tuner) /* Get tuner abilities */
#define VIDIOCSTUNER _IOW('v',5,struct video_tuner) /* Tune the tuner for the current channel */
#define VIDIOCGPICT _IOR('v',6,struct video_picture) /* Get picture properties */
#define VIDIOCSPICT _IOW('v',7,struct video_picture) /* Set picture properties */
#define VIDIOCCAPTURE _IOW('v',8,int) /* Start, end capture */
#define VIDIOCGWIN _IOR('v',9, struct video_window) /* Get the video overlay window */
#define VIDIOCSWIN _IOW('v',10, struct video_window) /* Set the video overlay window - passes clip list for hardware smarts , chromakey etc */
#define VIDIOCGFBUF _IOR('v',11, struct video_buffer) /* Get frame buffer */
#define VIDIOCSFBUF _IOW('v',12, struct video_buffer) /* Set frame buffer - root only */
#define VIDIOCKEY _IOR('v',13, struct video_key) /* Video key event - to dev 255 is to all - cuts capture on all DMA windows with this key (0xFFFFFFFF == all) */
#define VIDIOCGFREQ _IOR('v',14, unsigned long) /* Set tuner */
#define VIDIOCSFREQ _IOW('v',15, unsigned long)
linux内核中的，_OR,IOW这些是什么，在那个文件中有定义？？
为什么在不同硬件平台下，他们的值不同。 在平台相关的include目录下：
/include/asm-mips/ioctl.h
/include/asm-i386/ioctl.h
/include/asm-ppc/ioctl.h
... thanks up
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