device driver

[Tom]

Hi,

when trying to access the data register of a device I must first
perform a cast on the register address:

example:

int * data_register = (int *) 0xFFFF0000;

Can somebody explain me why the cast is needed ?

Thx,

T.

 

[Hal Murray]

when trying to access the data register of a device I must first
perform a cast on the register address:

example:

int * data_register = (int *) 0xFFFF0000;

Can somebody explain me why the cast is needed ?

Find a friendly software geek and get them to give you a lesson
in type checking.

Assuming
int x;

Roughly, it's so the compiler knows that data_register is a pointer
to an int rather than an int. So you need to write
x = *data_register
rather than
x = data_register

Having the compiler check for that sort of mixup catches a
huge fraction of simple programming bugs. (They are often
a pain to track down with traditional debugging methods.)

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