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[ARM] Some keil syntax questions

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love_electronic

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

Code: 
#define GPIOCONF(mode, cnf)	((cnf << 2) | (mode))
Is (cnf<<2) shifting 2 times here?

Code: 
#define CONFMASKL(pin) ((u32)~(15 << (pin * 4)))
what this statement tells?
 

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
 

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