#define MAXPACK 50
#define MAXBUFFERMS 100
#define MAXSTRIDE 3

#define SSS (((MAXPACK*MAXBUFFERMS*MAXSTRIDE + 4096) / 4096) * 4096)
struct snd_usX2Y_hwdep_pcm_shm {
	char playback[SSS];
	char capture0x8[SSS];
	char capture0xA[SSS];
	volatile int playback_iso_head;
	int playback_iso_start;
	struct {
		int	frame,
			offset,
			length;
	} captured_iso[128];
	volatile int captured_iso_head;
	volatile unsigned captured_iso_frames;
	int capture_iso_start;
};