startChip9.cpp

#include <fstream>
#include <iostream>
#include <stdio.h>
#include <map>
using namespace std;
constexpr int MEMORY_SIZE=0xFFF;
struct Chip8
{
   unsigned char memory[MEMORY_SIZE];
   bool loaded_rom;
   unsigned char Vx[16];
   unsigned short I;
   unsigned char dt;
   unsigned char st;
   short         PC;
   unsigned char stack;
   unsigned char screen[32*64];
};
namespace{
	
	typedef void (*registry_function)(Chip8 &chip8, unsigned short current);
	
	map<unsigned char, registry_function> registry_functions;
	
};

/*
	nnn or addr - A 12-bit value, the lowest 12 bits of the instruction
	n or nibble - A 4-bit value, the lowest 4 bits of the instruction
	x - A 4-bit value, the lower 4 bits of the high byte of the instruction
	y - A 4-bit value, the upper 4 bits of the low byte of the instruction
	kk or byte - An 8-bit value, the lowest 8 bits of the instruction
*/
#define EXTRACT_NNN(value)   value & 0x0FFF
#define EXTRACT_N(value)   value & 0x000F
#define EXTRACT_X(value)  (value>>8)&0x0F
#define EXTRACT_Y(value)  (value>>12)&0x0F
#define EXTRACT_KK(value) (value)&0xFF


void ShowHexBuffer(const char *tag, unsigned char *buffer, int length)
{
	int cols=0;
	int line_number=0;
	printf("%s:\n", tag);
	for(int i=0;i< length;i++)
	{
		if(cols==0)
			printf("%04d ", line_number);
		printf("%02x ", buffer[i]);
		cols++;
		if(cols==16)
		{
			for(int j=i;j<i+16;j++)
			{
			    printf("%c", (buffer[i]<31)?'0':buffer[i] );	
			}
			++line_number;
			printf("\n");
			cols =0;
		}
	}
}


void ReadROM(Chip8 &ref, const char *filename)
{
	fstream stream(filename, ios::in|ios::binary);
	if(stream.is_open())
	{
		int length =0;
		stream.seekg(0 , ios::end);
		length = stream.tellg();
		stream.seekg(0, ios::beg);
		cout <<"File Length "<< length <<"\n";
		
		stream.read((char *)&ref.memory[0x200], length);///block of rom start at 512 byte, before that address is reserved for the mach.
		ShowHexBuffer("ROM DUMP", ref.memory, length);
		ref.loaded_rom=true;
		stream.close(); 
	}
	else
	{
		cout <<"ROM Can't be opened\n";
	}
}

void Annn(Chip8 &ref, unsigned short opcode)
{

}


int main(int argc, char *argv[])
{
	Chip8 emulate;
	ReadROM(emulate,"Breakout.ch8");
	emulate.PC = 0;
	///while(emulate.loaded_rom)
	{
		
       	unsigned short current_instrucction = (emulate.memory[emulate.PC]<<8|emulate.memory[emulate.PC+1]);
       /// printf("%04x\n", current_instrucction);		
	   printf("\n\n\nValue %02x\n",EXTRACT_Y(current_instrucction));
		printf("\n\n\nValue NNN %04x\n",EXTRACT_NNN(current_instrucction));
	}

	return 0;
}