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Chip-8_Emu.c
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Chip-8_Emu.c
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#include "raylib.h"
#include "stdlib.h"
#include "math.h"
#include "stdio.h"
#include "string.h"
#define VRAM_START 0xF00
#define SCREEN_HEIGHT 32
#define SCREEN_WIDTH 64
#define FONT_START 0
struct Node {
struct Node* next;
struct Node* prev;
unsigned short address;
};
struct Stack {
struct Node* head;
struct Node* tail;
};
typedef struct Instruction {
unsigned short a : 4;
unsigned short b : 4;
unsigned short c : 4;
unsigned short d : 4;
} Instruction;
short firstTwo(Instruction in) {
short out = in.a << 4;
out |= in.b;
return out;
}
short lastTwo(Instruction in) {
short out = in.c << 4;
out |= in.d;
return out;
}
short lastThree(Instruction in) {
short out = in.b << 8;
out |= lastTwo(in);
return out;
}
int main(void)
{
// Initialization
//--------------------------------------------------------------------------------------
const int screenWidth = SCREEN_WIDTH * 12;
const int screenHeight = SCREEN_HEIGHT * 12;
InitWindow(screenWidth, screenHeight, "CHIP-8");
SetTargetFPS(60); // Set our game to run at 60 frames-per-second
unsigned char* memory = calloc(4096,1);
unsigned char registers[16];
short int addReg;
char delayTimer, soundTimer;
unsigned int PC = 0x200;
float tick = 0;
int keys[] = {KEY_ONE,KEY_TWO,KEY_THREE,KEY_FOUR,KEY_FIVE,KEY_SIX,KEY_SEVEN,KEY_EIGHT,KEY_NINE,KEY_A,KEY_B,KEY_C,KEY_D,KEY_E,KEY_F};
char font[] = { 0xF0, 0x90, 0x90, 0x90, 0xF0, // 0
0x20, 0x60, 0x20, 0x20, 0x70, // 1
0xF0, 0x10, 0xF0, 0x80, 0xF0, // 2
0xF0, 0x10, 0xF0, 0x10, 0xF0, // 3
0x90, 0x90, 0xF0, 0x10, 0x10, // 4
0xF0, 0x80, 0xF0, 0x10, 0xF0, // 5
0xF0, 0x80, 0xF0, 0x90, 0xF0, // 6
0xF0, 0x10, 0x20, 0x40, 0x40, // 7
0xF0, 0x90, 0xF0, 0x90, 0xF0, // 8
0xF0, 0x90, 0xF0, 0x10, 0xF0, // 9
0xF0, 0x90, 0xF0, 0x90, 0x90, // A
0xE0, 0x90, 0xE0, 0x90, 0xE0, // B
0xF0, 0x80, 0x80, 0x80, 0xF0, // C
0xE0, 0x90, 0x90, 0x90, 0xE0, // D
0xF0, 0x80, 0xF0, 0x80, 0xF0, // E
0xF0, 0x80, 0xF0, 0x80, 0x80}; // F
for (int i = 0; i < 16 * 5; i++){
memory[FONT_START + i] = font[i];
}
struct Stack* stack = malloc(sizeof(struct Stack));
//Load ROM into memory
{
FILE *fp;
char *ptr = &(memory[512]);
fp = fopen("ROMS\\Pong [Paul Vervalin, 1990].ch8","rb");
if (!fp) {
printf("Error, file not opened");
return 0;
}
fseek(fp, 0, SEEK_END);
long size = ftell(fp);
printf("%u",size);
fseek(fp,0,SEEK_SET);
fread(ptr, 1, size, fp);
fclose(fp);
}
// Main game loop
BeginDrawing();
ClearBackground(BLACK);
EndDrawing();
while (!WindowShouldClose()) // Detect window close button or ESC key
{
tick += GetFrameTime()*60;
if (tick>1) {
if (delayTimer > 0) delayTimer--;
else delayTimer = 0;
if (soundTimer > 0) soundTimer--;
else soundTimer = 0;
tick = 0;
}
Instruction inst;
inst.a = memory[PC] >> 4 & 0xf;
inst.b = memory[PC] & 0xf;
inst.c = memory[PC+1] >> 4 & 0xf;
inst.d = memory[PC+1] & 0xf;
unsigned short regX,regY,val,op,out;
struct Node* new;
//printf("PC:%x a:%x b:%x c:%x d:%x\n", PC, inst.a, inst.b, inst.c, inst.d);
//printf("INSTRUCTION:%x%x\n", memory[PC], memory[PC+1]);
switch (inst.a){
case 0:
if (lastTwo(inst) == 0xE0) {
BeginDrawing();
for (int x = 0; x < SCREEN_WIDTH; x+=8){
for (int y = 0; y < SCREEN_HEIGHT; y++){
memory[VRAM_START+y*8+x/8] = 0;
}
}
ClearBackground(BLACK);
EndDrawing();
//printf("CLEAR\n");
}
else if (lastTwo(inst) == 0xEE){
struct Node* stor = stack->tail;
PC = stor->address;
stack->tail = stor->prev;
free(stor);
}
break;
case 1:
out = lastThree(inst);
//printf("JUMP: %x\n",out);
PC = out-2;
break;
case 2:
new = malloc(sizeof(struct Node));
new->address = PC;
if (!stack->head) {
stack->head = new;
stack->tail = new;
}
else{
new->prev = stack->tail;
stack->tail = new;
}
out = lastThree(inst);
PC = out - 2;
break;
case 3:
//printf("Comparison: reg %x == %x\n",regX, val);
if (registers[inst.b] == lastTwo(inst)) PC+=2;
break;
case 4:
//printf("Comparison: reg %x != %x\n",regX, val);
if (registers[inst.b] != lastTwo(inst)) PC+=2;
break;
case 5:
//printf("Comparison: reg %x == reg %x\n",regX, regY);
if (registers[inst.b] == registers[inst.c]) PC+=2;
break;
case 6:
//printf("SET: reg %x = %x\n",regX, val);
registers[inst.b] = lastTwo(inst);
break;
case 7:
//printf("ADD: reg %x += %x\n",regX, val);
registers[inst.b] += lastTwo(inst);
break;
case 8:
regX = inst.b;
regY = inst.c;
switch (inst.d) {
case 0:
registers[regX] = registers[regY];
break;
case 1:
registers[regX] |= registers[regY];
break;
case 2:
registers[regX] &= registers[regY];
break;
case 3:
registers[regX] ^= registers[regY];
break;
case 4:
out = registers[regX] + registers[regY];
if (out < registers[regX] || out < registers[regY]) registers[0xF] = 1;
else registers[0xF] = 0;
registers[regX] = out;
break;
case 5:
out = registers[regX] - registers[regY];
if (registers[regX] >= registers[regY]) registers[0xF] = 1;
else registers[0xF] = 0;
registers[regX] = out;
break;
case 6:
registers[0xF] = registers[regX]%2;
registers[regX] >>= 1;
break;
case 7:
out = registers[regY] - registers[regX];
if (registers[regY] >= registers[regX]) registers[0xF] = 1;
else registers[0xF] = 0;
registers[regX] = out;
break;
case 0xE:
registers[0xF] = registers[regX]>>7;
registers[regX] <<= 1;
break;
}
break;
case 9:
//printf("Comparison: reg %x != reg %x\n",regX, regY);
if (registers[inst.b] != registers[inst.c]) PC+=2;
break;
case 0xA:
addReg = lastThree(inst);
//printf("LOC: I= %x\n", out);
break;
case 0xB:
PC = registers[0] + lastThree(inst);
break;
case 0xC:
registers[inst.b] = rand()&lastTwo(inst);
break;
case 0xD:
regX = inst.b;
regY = inst.c;
val = inst.d;
out = 0;
//printf("DRAW: (%u,%u)\n",registers[regX],registers[regY]);
for (int y = 0; y < val; y++) {
unsigned char a1 = memory[addReg + y]>>(registers[regX]%8);
unsigned char a2 = memory[addReg + y]<<((8-(registers[regX]%8)));
unsigned char* b1 = &memory[VRAM_START + (registers[regY]+y)*8+registers[regX]/8];
unsigned char* b2 = &memory[VRAM_START + (registers[regY]+y)*8+registers[regX]/8+1];
//memory[VRAM_START + y*8 + x/8]
//printf("%x %x\n",*b1,*b2);
//printf("%x %x %x\n",memory[addReg + y],a1,a2);
if (a1&*b1 > 0 || a2&*b2 > 0) out = 1;
*b1 ^= a1;
*b2 ^= a2;
//printf("%x %x\n",*b1,*b2);
}
//printf("%u\n",out);
registers[0xF] = out;
//memory[VRAM_START] = 0xFF;
BeginDrawing();
ClearBackground(BLACK);
for (int x = 0; x < SCREEN_WIDTH; x++){
for (int y = 0; y < SCREEN_HEIGHT; y++) {
Color col;
if ((memory[VRAM_START + y*8 + x/8]>>(7-x%8))%2) DrawRectangle(x*12,y*12,12,12,WHITE);
}
}
EndDrawing();
break;
case 0xE:
printf("Checkkey %x\n", registers[inst.b]);
if (lastTwo(inst) == 0x9E) {
if (IsKeyDown(keys[registers[inst.b]])){
PC += 2;
}
}
else if (lastTwo(inst) == 0xA1) {
if (!IsKeyDown(keys[registers[inst.b]])){
PC += 2;
}
}
break;
case 0xF:
regX = inst.b;
switch (lastTwo(inst))
{
case 0x07:
registers[regX] = delayTimer;
break;
case 0x0A:
//Need to implement
break;
case 0x15:
delayTimer = registers[regX];
break;
case 0x18:
soundTimer = registers[regX];
break;
case 0x1E:
addReg += registers[regX];
break;
case 0x29:
addReg = FONT_START + registers[regX]*5;
break;
case 0x33:
//printf("BCD: RegX = %u, ", registers[regX]);
out = registers[regX];
for (int i = 2; i>=0; i--) {
memory[addReg + 2-i] = out/pow(10,i);
//printf("%u, ",memory[addReg + 2-i]);
out %= (int)pow(10,i);
}
//printf("\n");
break;
case 0x55:
//printf("REGDUMP: From Reg[0] to Reg[%x]\n",regX);
for (int i = 0; i <= regX; i++){
memory[addReg+i] = registers[i];
//printf("REGDUMP: Reg[%x] = %u\n",i, registers[i]);
}
break;
case 0x65:
//printf("REGGET: From Reg[0] to Reg[%x]\n",regX);
for (int i = 0; i <= regX; i++){
registers[i] = memory[addReg+i];
//printf("REGGET: Reg[%x] = %u\n",i, registers[i]);
}
break;
}
break;
}
PC+=2;
}
// De-Initialization
//--------------------------------------------------------------------------------------
CloseWindow(); // Close window and OpenGL context
//--------------------------------------------------------------------------------------
return 0;
}