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366 lines (323 loc) · 10.5 KB
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//
// Created by Martin on 21/10/2017.
//
#include <iostream>
#include <time.h>
#include <fstream>
#include <vector>
#include <assert.h>
#include <cstring>
#include "Base8Chip.h"
unsigned char const chip8_fontset[80] =
{
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
};
unsigned short Base8Chip::get_pc(){
return pc;
}
void Base8Chip::get_mem(char* receive) {
for(int x = 0;x < 4096;x++){
receive[x] = memory[x];
}
}
void Base8Chip::init() {
//inits
srand(time(NULL));
drawFlag = true;
pc = 0x200;
opcode = 0;
I = 0;
sp = 0;
sound_timer = 0;
delay_timer = 0;
//Zeroes the memory
fill(key, key+16, 0);
fill(stack, stack+16, 0);
fill(V, V+16, 0);
fill(memory, memory+4096, 0);
fill(gfx, gfx+(32*64), 0);
//Load fonts
for(int i = 0;i < 80;i++){
memory[i] = chip8_fontset[i];
}
}
void Base8Chip::emulateCycle() {
//Fetch opcode
opcode = memory[pc] << 8 | memory[pc + 1];
//Decode opcode and exec
switch (opcode & 0xF000) {
case 0x0000:
switch (opcode & 0x000F) {
//CLS : Clear screen
case 0x0000:
fill(gfx, gfx + (32 * 64), 0);
drawFlag = true;
pc += 2;
break;
//RET : return from current subrutine
case 0x000E:
--sp;
pc = stack[sp];
pc += 2;
break;
}
break;
//JP : Goto subroutine
case 0x1000:
pc = opcode & 0x0FFF;
break;
//CALL : Call subroutine at address
case 0x2000:
stack[sp] = pc;
++sp;
pc = opcode & 0x0FFF;
break;
//SE : Skip next if ==
case 0x3000:
if (V[(opcode & 0x0F00) >> 8] == (opcode & 0x00FF))
pc += 2;
pc += 2;
break;
//SNE : Skip next if !=
case 0x4000:
if (V[(opcode & 0x0F00) >> 8] != (opcode & 0x00FF))
pc += 2;
pc += 2;
break;
//SE : Skip next if Vx = Vy
case 0x5000:
if (V[(opcode & 0x0F00) >> 8] == V[(opcode & 0x00F0) >> 4])
pc += 2;
pc += 2;
break;
//LD : 0x0yxx Puts xx en Vy
case 0x6000:
V[(opcode & 0x0F00) >> 8] = opcode & 0x00FF;
pc += 2;
break;
//ADD : 0x0yxx Vx+=y
case 0x7000:
V[(opcode & 0x0F00) >> 8] += opcode & 0x00FF;
pc += 2;
break;
case 0x8000:
switch (opcode & 0x000F) {
//LD : 0x0xy0 Vx = Vy
case 0x0000:
V[(opcode & 0x0F00) >> 8] = V[(opcode & 0x00F0) >> 4];
pc += 2;
break;
//OR : Vx = Vx | Vy
case 0x0001:
V[(opcode & 0x0F00) >> 8] |= V[(opcode & 0x00F0) >> 4];
pc += 2;
break;
//AND : Vx = Vx & Vy
case 0x0002:
V[(opcode & 0x0F00) >> 8] &= V[(opcode & 0x00F0) >> 4];
pc += 2;
break;
//XOR : Vx = Vx ^ Vy
case 0x0003:
V[(opcode & 0x0F00) >> 8] ^= V[(opcode & 0x00F0) >> 4];
pc += 2;
break;
//ADD : Vx = Vx + Vy (carry)
case 0004:
if (V[(opcode & 0x00F0) >> 4] > (0xFF - V[(opcode & 0x0F00) >> 8]))
V[0xF] = 1;
else
V[0xF] = 0;
V[(opcode & 0x0F00) >> 8] += V[(opcode & 0x00F0) >> 4];
pc += 2;
break;
case 0x0005:
if (V[(opcode & 0x00F0) >> 4] > V[(opcode & 0x0F00) >> 8])
V[0xF] = 0;
else
V[0xF] = 1;
V[(opcode & 0x0F00) >> 8] -= V[(opcode & 0x00F0) >> 4];
pc += 2;
break;
case 0x0006:
V[0xF] = V[(opcode & 0x0F00) >> 8] & 0x1;
V[(opcode & 0x0F00) >> 8] >>= 1;
pc += 2;
break;
case 0x0007:
if (V[(opcode & 0x0F00) >> 8] > V[(opcode & 0x00F0) >> 4])
V[0xF] = 0;
else
V[0xF] = 1;
V[(opcode & 0x0F00) >> 8] = (V[(opcode & 0x00F0) >> 4] - V[(opcode & 0x0F00) >> 8]);
pc += 2;
break;
case 0x000E:
V[0xF] = V[(opcode & 0x0F00) >> 8] >> 7;
V[(opcode & 0x0F00) >> 8] <<= 1;
pc += 2;
break;
}
break;
case 0x9000:
if (V[(opcode & 0x0F00) >> 8] != V[(opcode & 0x00F0) >> 4])
pc += 2;
pc += 2;
break;
case 0xA000:
I = opcode & 0x0FFF;
pc += 2;
break;
case 0xB000:
pc = (opcode & 0x0FFF) + V[0];
break;
case 0xC000:
V[(opcode & 0x0F00) >> 8] = (rand() % 0xFF) & (opcode & 0x00FF);
pc += 2;
break;
case 0xD000: {
unsigned short x = V[(opcode & 0x0F00) >> 8];
unsigned short y = V[(opcode & 0x00F0) >> 4];
unsigned short h = opcode & 0x000F;
unsigned short pixel;
V[0xF] = 0;
for (int ypos = 0; ypos < h; ypos++) {
pixel = memory[I + ypos];
for (int xpos = 0; xpos < 8; xpos++) {
if ((pixel & (0x80 >> xpos)) != 0) {
if (gfx[(x + xpos + ((y + ypos) * 64))] == 1)
V[0xF] = 1;
gfx[x + xpos + ((y + ypos) * 64)] ^= 1;
}
}
}
drawFlag = true;
pc += 2;
}break;
case 0xE000:
switch (opcode & 0x00FF)
{
case 0x009E:
if (key[V[(opcode & 0x0F00) >> 8]] != 0)
pc += 4;
else
pc += 2;
break;
case 0x00A1:
if (key[V[(opcode & 0x0F00) >> 8]] == 0)
pc += 4;
else
pc += 2;
break;
}
break;
case 0xF000:
switch(opcode & 0x00FF)
{
case 0x0007:
V[(opcode & 0x0F00) >> 8] = delay_timer;
pc+=2;
break;
case 0x000A:
{
bool is_pressed = false;
for (int i = 0; i < 16; i++) {
if (key[i] == 1) {
V[(opcode & 0x0F00) >> 8] = i;
is_pressed = true;
}
}
if (!is_pressed)
return;
pc += 2;
}break;
case 0x0015:
delay_timer = V[(opcode & 0x0F00) >> 8];
pc += 2;
break;
case 0x0018:
sound_timer = V[(opcode & 0x0F00) >> 8];
pc+=2;
break;
case 0x001E:
if(I + V[(opcode & 0x0F00) >> 8 ] > 0xFFF)
V[0xF] = 1;
else
V[0xF] = 0;
I += V[(opcode & 0x0F00) >> 8];
pc+=2;
break;
case 0x0029:
I = V[(opcode & 0x0F00) >> 8] * 0x5;
pc += 2;
break;
case 0x0033:
memory[I] = V[(opcode & 0x0F00) >> 8] / 100;
memory[I + 1] = (V[(opcode & 0x0F00) >> 8] / 10) % 10;
memory[I + 2] = (V[(opcode & 0x0F00) >> 8] % 100) % 10;
pc += 2;
break;
case 0x0055:
for(int x = 0;x < ((opcode & 0x0F00) >> 8);++x){
memory[I+x] = V[x];
}
I += ((opcode & 0x0F00) >> 8) +1;
pc+=2;
break;
case 0x0065:
for(int x = 0; x <= ((opcode & 0x0F00) >> 8);++x){
V[x] = memory[I + x];
}
I += ((opcode & 0x0F00) >> 8) +1;
pc+=2;
break;
}
break;
default:
std::cout << "Unknown opcode";
}
//Update timers
if (delay_timer > 0)
--delay_timer;
if (sound_timer > 0) {
if(sound_timer == 1){
std::cout << "BEEP!";
} //TODO add real sound
else {
--sound_timer;
}
}
}
void Base8Chip::loadGame(string name) {
ifstream file(name, ios::binary | ios::ate);
streamsize size = file.tellg();
assert(size <= (4096-512));
file.seekg(0, ios::beg);
vector<char> buffer(size);
if(file.read(buffer.data(), size))
{
for(int x = 0;x < size;x++){
memory[x+512] = buffer[x];
}
}
file.close();
}
//Set state of a key
void Base8Chip::setKey(const unsigned char addr, const char state) {
key[addr] = state;
}