Question on function syntax and calling function

Ok, I was given a function to fill out for a programming assignment.

The function header is as follows:

Code:

---


insert_ready(pcb)
PCB* pcb;
{

}

---

I have never seen syntax like this before, what does it mean?

Normally all the functions I have written/seen are like this.

Code:

---


insert_ready(PCB * pcb){

}

---

The reason I am asking is when I call the function insert_ready in another function I am getting an error.

line 164: identifier redeclared: insert_ready
current : function() returning void
previous: function() returning int : "cpu.c", line 133

When I am calling the function i am calling it as:

Code:

---

PCB* preempted; // was declared in the calling function

insert_ready(preempted);

---

Any ideas?

Thank you.

Code:

---

insert_ready(pcb)
PCB* pcb;
{

}

---

That's the old C style function definition. You should avoid it if possible because it's not good at checking types and when mixed with the new style that you (and everyone else :D) is used to, you can easily have problems.

is the suffix the returning value or something?

-LC

>is the suffix the returning value or something?
No, it's the parameter. These two functions are basically the same (except the first is old and ugly and nasty and evil and deprecated :D):

Code:

---

funkshun(); /* Declaration */

funkshun(arg) /* Definition */
int arg;
{
  /* Do stuff with arg */
}

---

Code:

---

int funkshun(int arg); /* Declaration */

int funkshun(int arg) /* Definition */
{
  /* Do stuff with arg */
}

---

thanks, I changed it to the new style and it gives me pretty much the same error:

line 164: identifier redeclared: insert_ready
current : function(pointer to struct pcb_node {int pcb_id, int size, int creation_time, int last_dispatch, int last_cpuburst, int accu...
previous: function() returning int : "cpu.c", line 133

Line 164 is the function insert_ready(PCB* pcb)

Line 133 is the function call in a function called dispatch.
The only way to access the pcb that I am trying to call is by a pointer on a structure which contains a pointer to a pcb.

PTBR->pcb,
I have tried making the call several ways and it gives an error every time.

Code:

---


PTBR* preempted;
....
preempted=PTBR->pcb;
insert_ready(preempted);

or
PTBR *preempted;
PTBR preempted_pcb;

preempted_pcb=*(PTBR->pcb);
preempted=&preempted_pcb;
insert_ready(preempted);

---

Any suggestions?

Thanks

>> previous: function() returning int : "cpu.c", line 133
You need a function prototype. This error would suggest you simply called your function with no parameters too.

Stick this in your .h file, or at least at the top of your .c file if you're only using that function in one .c file.

void insert_ready(PCB*);

I don't know what return type you require, so change the "void" part to whatever you need.

hmmm,

Well I see what you are saying but I cannot do this. The assignment is/has already been written, the main .c file is not able to be modified. We were handed a cpu.c file and were told to write the code for the three functions hence why I did not understand the syntax on the one function.

I am under the assumption that the main program it is linked to already has the function prototype done for us.

The way the shell was written it had the function insert_ready() after dispatch.

Dispatch calls insert_ready(), so i switched their position in the cpu.c file and it compiles fine now.

Thanks for the heads up.

Swapping functions around to get the to work means you haven't got correct prototyping. It's up to you if you want fix it or not, but I'd suggest you do.

Well I try to prototype the 3 functions in the .c file we are supposed to modify and it gives me all of these errors:
line 10: warning: old-style declaration or incorrect type for: cpu_init
"cpu.c", line 11: syntax error before or at: *
"cpu.c", line 11: warning: old-style declaration or incorrect type for: insert_ready
"cpu.c", line 12: warning: old-style declaration or incorrect type for: dispatch
"cpu.c", line 112: identifier redeclared: cpu_init
current : function() returning void
previous: function() returning int : "cpu.c", line 10
"cpu.c", line 122: identifier redeclared: insert_ready
current : function() returning void
previous: function() returning int : "cpu.c", line 11
"cpu.c", line 205: identifier redeclared: dispatch
current : function() returning void
previous: function() returning int : "cpu.c", line 12

This cpu.c file is used by an Operating System simulator called osp. It is hard to explain, but this simulator program is what calls these functions. Anyways the whole shell of the cpu.c file is provided but with empty functions. If you would like to see what I am talking about here is the same assignment from another schools website.....

http://data.uta.edu/~ramesh/cse3320/project1-2.html

My guess is that you put the prototypes before the definition of PCB, which is typedef'd struct pcb_node.

The compiler cannot look forward in your source to find things it doesn't recognise, so you have to make sure everything you're using on the current line is already known about.

There might be other probs too, it's hard to tell without seeing your code. If you want post it here and someone will advise.

Thank you very much, that seems to work as well. I assumed they had prototyped the 3 functions already but when I got errors I tried putting it in. For some reason at the top of the file, above the constants it would give me an error.

I prototyped the functions after the typedef's and it worked just fine.

Thanks for all your help Hammer. :D

The rest of the code works fine now. I just have to implement aging on processes preempted back to the ready queue and I am good to go. That is the only warning the simulator issues, and that is because I havent written the code to implement aging yet. I wanted to get a FCFS implementation working first before I add the aging. the Round robin interrupt quantum works as well.