I need help in C programming please!!

[Big-Byte]

Ok.. Ive got 3 files....

registers.h

typedef struct REG {
u8 A,F; // Accumulator / Flag
u8 B,C,D,E,H,L; // General purpose 8 bit registers
int AF, BC, DE, HL; // 16 bit registers.
int PC; // Program Counter
int SP; // Stack Pointer.
} REG;

main.c

#include registers.h

REG registers;
REG* regPtr;

can use regPtr fine in here.... ie regPtr->PC = 0x100; etc..

general.c

How can I get access to the register structure in this file?

I want to be able to pass the regPtr into a function in this file and
use it the same way as above.. ie: regPtr->PC = 0x100; etc..

Ive tried using the extern keyword and currently my code looks like...

void disp_current_instr(u8* mem)
{
extern registers;
regPtr = &registers;

dispMessage(0, 0, word_to_str(mem[regPtr->PC]), " ");

but it doesnt work...

Hope someone can understand what Im going on about..

[§ane]

// *** registers.h ***

typedef unsigned char u8;

typedef struct REG {
u8 A,F; // Accumulator / Flag
u8 B,C,D,E,H,L; // General purpose 8 bit registers
int AF, BC, DE, HL; // 16 bit registers.
int PC; // Program Counter
int SP; // Stack Pointer.
} REG;

extern REG registers;
extern REG* regPtr;


// *** general.c ***

#include "registers.h"

void disp_current_instr(u8* mem)
{
regPtr = & registers;

dispMessage(0, 0, word_to_str(mem[regPtr->PC]), " ");
}


// *** main.c ***

#include "registers.h"

REG registers;
REG* regPtr;

void main(void)
{
// stuff

disp_current_instr(stuff);

// more stuff
}

[Big-Byte]

That worked a treat.. Thanks Sane...

[Big-Byte]

Heres are a couple of screenshots of what Im working on - a Gameboy emulator for the Gameboy Advance in action.

As you can see its still in VERY early stages and only implements one opcode.... JP $aabb (two if you count NOP) but its a start!!!

[Big-Byte]

And after executing next instruction......

[P-J]

Nice project mate, hope it works out well.

It's the simple things that are over looked, don't you think? A GB emu for the GBA seems like an obvious path.

You'll make a lot of friends if you finish that

[Big-Byte]

Unfortunately I havent done any more to it My work actually found me some 'real' work to do so I never had time..

Will pick it up again at some point.