4.g assignment HELP

[iamborg1of1]

4.g assignment

Hi in asm you have this piece of code

datawaiting:
movlw 32
andwf _pir1,0
bz datawaiting
movf _rcreg,0
movwf tmp

all of this I understand no problem but when it is converted to C
as follows

while(!(pir1 & 32));

For the love of god I cannot get my head around it ,is there any one who could explain to me what it does,
Peter

[geenbert]

The part:

movf _rcreg,0 movwf _tmp 

(note the underscore preceding temp) is translated to

tmp=rcreg;

So what remains is this:

datawaiting:movlw 32            // load 32 in wandwf _pir1,0       // AND w with pir1bz datawaiting      // if 0 (so not true) branch                          (jump) to datawaiting

Which is indeed translated to:

while(!(pir1 & 32)); 

If you "dissect" the C command you get:

pir1 & 32        meaning: AND 32 with pir1while(!     )        meaning: loop while the condition                   is not true   

Both mean the same: "if pir1 AND 32 is false stay in this loop".

Perhaps the explanations on page 98 and 138 are of help.


I've edited this three time but it's quite hard to get the code lined-up nicely.