[ARM] Some keil syntax questions

[love_electronic]

Hi
I wanna ask some basic questions regarding keil uvision syntax.
what are the functions of following statement

#define GPIOCONF(mode, cnf)	((cnf << 2) | (mode))

Is (cnf<<2) shifting 2 times here?

#define CONFMASKL(pin) ((u32)~(15 << (pin * 4)))

what this statement tells?

 

[Gorgon]

Those are normal macro definitions.

The first shift the value of 'cnf' 2 bits to the left making room for ORing in 'mode'. I would suppose that mode is in the range 0-3.

The second makes an inverted 32 bit unsigned integer mask of 4 bits dependent on the 'pin' value, range 0-7. Like pin=0: 0xFFFFFFF0, to pin=7: 0x0FFFFFFF