Thread: Pointer and typecasting question

This is a piece of code from the C setup of a cross platform console system.

Now I'm a bit familiar with pointers and typecasting, however this setup is confusing to me.

Code:

*(unsigned short int *) 0xf00400 = 0x0000; /* Color reg 0 = black */
  *(unsigned short int *) 0xf00402 = 0xffff; /* Color reg 1 = white */

Now I know its a typecast but I'm use to seeing them something like this:

n3.next=( struct entry *) 0; or somesuch.

Can someone clarify for me what kind of pointer setup this is? a hex pointer?

Thanks for your insight.

Originally Posted by quzah

All variables hold values - numbers really - and this is just skipping the step of actually having a variable. You telling the compiler that the value represents the value a pointer would normally be storing (a spot in memory), and manipulating that spot directly. There's a good chance your OS is going to frown upon that.


Quzah.

oh ok so its basically pointing directly at a memory location '0xf00400' and sticking the value '0x0000' in there?

Yes. And furthermore treating that memory destination as "short" - which is a 2-byte (16 bit value). So the 0x0000 and 0xffff will mash 2 bytes each. No more, no less.