looking at f_uac2.c I found this interresting piece of code:
|struct audio_dev {
| /* Currently active {Interface[15:8] | AltSettings[7:0]} */
| __u16 ac_alt, as_out_alt, as_in_alt;
|â?Š
|};
|
|â?Š
|#define ALT_SET(x, a) do {(x) &= ~0xff; (x) |= (a); } while (0)
|#define ALT_GET(x) ((x) & 0xff)
|#define INTF_SET(x, i) do {(x) &= 0xff; (x) |= ((i) << 8); } while (0)
|#define INTF_GET(x) ((x >> 8) & 0xff)
|â?Š
| ALT_SET(agdev->as_out_alt, 0);
| INTF_SET(agdev->as_out_alt, ret);
|â?Š
Could one of you two explain to me why smashing two different things (an
interface number and an alternative setting number) into one variable
and using a Macro to seperate them again was a good idea?
Sebastian
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