Passing a predefined variable as a pointer in C - c

Question

I tried to write a PIC program with C and what it does is turn on a series of 8 LED's (like Knight Rider LED illumination :D ). I have created the circuit design and tested with a simple c program that sets the state of the lights and it works. Now I want to streamline my code.
So i have created 2 functions for delaying and getting the required HEX value of the LED. the 2 methods are like this.
#define MAX 8
#define LEFT 1
#define RIGHT 2
#define BOTH 0
void delay_ms(int ms) {
while(ms > 0)
ms--;
}
int getHex(int delay, int dir, int *pin) {
int hex[] = {0x01, 0x02, 0x04, 0x10, 0x20, 0x40, 0x80};
if (dir == RIGHT) {
for (int i = 0; i < MAX; i++)
{
*pin = hex[i];
delay_ms(delay);
}
} else if( dir == LEFT ) {
for (int i = MAX - 1; i == 0; i--)
{
pin = hex[i];
delay_ms(delay);
}
}
}
and i have this in the main() function
main() {
TRISA = 1;
TRISB = 0;
while(1) {
if(RA0 == 0)
getHex(5000, RIGHT, PORTB);
}
}
What im trying to do is pass the PORTB predefined variable as a pointer to the function so it is set with the proper hex value. But i get the following warnings when i compile with the MPLAB IDE,
Warning [357] D:\...\main.c; 24.13 illegal conversion of integer to pointer
Warning [357] D:\...\main.c; 37.22 illegal conversion of integer to pointer
and when the program hex is added and run in the Proteus 8 nothing happens and the following warning appears.
[PIC16 MEMORY]PC=0x03AF. Attempt to write unimplemented memory location 0x0087 with 0x01 ignored
[PIC16 MEMORY]PC=0x03AF. Attempt to write unimplemented memory location 0x0087 with 0x02 ignored
[PIC16 MEMORY]PC=0x03AF. Attempt to write unimplemented memory location 0x0087 with 0x04 ignored
the final Hex value in the error correspond with the hex value i am trying to set as the value of PORTB. What am i doing wrong.. Please help.

Answer 1

There are several ways that such pre-defined registers may be declared. I don't know how Mplab does it, but the most common way is this:
#define PORTB (*(volatile uint8_t*)0x1234)
where 0x1234 is the hardware address of that register. This macro accesses the register directly, but the * to the left makes it so that you can use the macro as if PORTB was an ordinary variable and not a pointer.
If this is the case, then you need to pass &PORTB to your function that expects a pointer.

Answer 2

Changed the getHex Method definition to this.
int getHex(int delay, int dir, int *pin) {
int hex[] = {0x01, 0x02, 0x04, 0x10, 0x20, 0x40, 0x80};
if (dir == RIGHT) {
for (int i = 0; i < MAX; i++)
{
*pin = hex[i];
delay_ms(delay);
}
} else if( dir == LEFT ) {
for (int i = MAX - 1; i == 0; i--)
{
*pin = hex[i];
delay_ms(delay);
}
}
}
and then called the function with the following..
getHex(2000, RIGHT, &PORTB);