CHIP-8 e' un linguaggio di programmazione interpretato che girava in macchina virtuale su macchine di fine anni 70 come COSMAC VIP
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| TelMac 1800 |
La partenza di tutto e' un codice di James Griffin disponibile su GitHub che simula CHIP-8 mediante la libreria SDL
Per semplificare il progetto da portare su Arduino ho creato un progetto intermedio con grafica testuale con NCurses che rimuove la dipendenza dal file system (la rom non viene piu' caricata da un file ma e' inclusa in modo statico in un array nel codice..nel file main.cpp c'e' un programma MAZE commentato ed un programma PONG non commentato)
main.cpp
---------------------------------------------------------------
#include <chrono>
#include <thread>
#include "stdint.h"
#include <curses.h>
#include <math.h>
#include "chip8.h"
using namespace std;
//MAZE
/*
static unsigned char prg[] =
{
0xA2,0x1E, 0xC2, 0x01, 0x32, 0x01, 0xA2, 0x1A,
0xD0,0x14, 0x70, 0x04, 0x30, 0x40, 0x12, 0x00,
0x60,0x00, 0x71, 0x04, 0x31, 0x20, 0x12, 0x00,
0x12,0x18, 0x80, 0x40, 0x20, 0x10, 0x20, 0x40,
0x80,0x10
};
*/
//PONG
static unsigned char prg[] =
{
0x6A,0x02, 0x6B, 0x0C, 0x6C, 0x3F, 0x6D, 0x0C,
0xA2,0xEA, 0xDA, 0xB6, 0xDC, 0xD6, 0x6E, 0x00,
0x22,0xD4, 0x66, 0x03, 0x68, 0x02, 0x60, 0x60,
0xF0,0x15, 0xF0, 0x07, 0x30, 0x00, 0x12, 0x1A,
0xC7,0x17, 0x77, 0x08,
0x69,0xFF, 0xA2, 0xF0, 0xD6, 0x71, 0xA2, 0xEA,
0xDA,0xB6, 0xDC, 0xD6, 0x60, 0x01, 0xE0, 0xA1,
0x7B,0xFE, 0x60, 0x04, 0xE0, 0xA1, 0x7B, 0x02,
0x60,0x1F, 0x8B, 0x02, 0xDA, 0xB6, 0x60, 0x0C,
0xE0,0xA1, 0x7D, 0xFE,
0x60,0x0D, 0xE0, 0xA1, 0x7D, 0x02, 0x60, 0x1F,
0x8D,0x02, 0xDC, 0xD6, 0xA2, 0xF0, 0xD6, 0x71,
0x86,0x84, 0x87, 0x94, 0x60, 0x3F, 0x86, 0x02,
0x61,0x1F, 0x87, 0x12, 0x46, 0x02, 0x12, 0x78,
0x46,0x3F, 0x12, 0x82,
0x47,0x1F, 0x69, 0xFF, 0x47, 0x00, 0x69, 0x01,
0xD6,0x71, 0x12, 0x2A, 0x68, 0x02, 0x63, 0x01,
0x80,0x70, 0x80, 0xB5, 0x12, 0x8A, 0x68, 0xFE,
0x63,0x0A, 0x80, 0x70, 0x80, 0xD5, 0x3F, 0x01,
0x12,0xA2, 0x61, 0x02,
0x80,0x15, 0x3F, 0x01, 0x12, 0xBA, 0x80, 0x15,
0x3F,0x01, 0x12, 0xC8, 0x80, 0x15, 0x3F, 0x01,
0x12,0xC2, 0x60, 0x20, 0xF0, 0x18, 0x22, 0xD4,
0x8E,0x34, 0x22, 0xD4, 0x66, 0x3E, 0x33, 0x01,
0x66,0x03, 0x68, 0xFE,
0x33,0x01, 0x68, 0x02, 0x12, 0x16, 0x79, 0xFF,
0x49,0xFE, 0x69, 0xFF, 0x12, 0xC8, 0x79, 0x01,
0x49,0x02, 0x69, 0x01, 0x60, 0x04, 0xF0, 0x18,
0x76,0x01, 0x46, 0x40, 0x76, 0xFE, 0x12, 0x6C,
0xA2,0xF2, 0xFE, 0x33,
0xF2,0x65, 0xF1, 0x29, 0x64, 0x14, 0x65, 0x00,
0xD4,0x55, 0x74, 0x15, 0xF2, 0x29, 0xD4, 0x55,
0x00,0xEE, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
0x80,0x00, 0x00, 0x00, 0x00, 0x00
};
int tasto;
uint8_t keymap[16];
#define SCREEN_WIDTH 64
#define SCREEN_HEIGHT 32
int main() {
Chip8 chip8 = Chip8();
initscr();
cbreak();
noecho();
clear();
timeout(0); // per fare kbhit non bloccante
uint32_t pixels[2048];
chip8.load(prg,sizeof(prg));
while (true) {
chip8.emulate_cycle();
for (int f=0;f<16;++f)
{
chip8.key[f] = 0;
}
tasto = getch();
switch (tasto)
{
case 49 : //1
chip8.key[1] = 1;
break;
case 113 : //q
chip8.key[4] = 1;
break;
case 97 : //a
chip8.key[7] = 1;
break;
case 122 : //z
chip8.key[10] = 1;
break;
case 50 : //2
chip8.key[2] = 1;
break;
case 119 : //w
chip8.key[5] = 1;
break;
case 115 : //s
chip8.key[8] = 1;
break;
case 120 : //x
chip8.key[0] = 1;
break;
case 51 : //3
chip8.key[3] = 1;
break;
case 101 : //e
chip8.key[6] = 1;
break;
case 100 : //d
chip8.key[9] = 1;
break;
case 99 : //c
chip8.key[11] = 1;
break;
case 52 : //4
chip8.key[12] = 1;
break;
case 114 : //r
chip8.key[13] = 1;
break;
case 102 : //f
chip8.key[14] = 1;
break;
case 118 : //v
chip8.key[15] = 1;
break;
case 27:
endwin();
exit(0);
break;
default:
break;
}
if (chip8.drawFlag) {
chip8.drawFlag = false;
clear();
for (int i = 0; i < 2048; ++i) {
uint8_t pixel = chip8.gfx[i];
int k = (int)i/64;
int j = i%64;
if (pixel == 1)
{
move(k,j);
addch(ACS_CKBOARD);
}
}
refresh();
}
std::this_thread::sleep_for(std::chrono::microseconds(12000));
}
}
---------------------------------------------------------------
chip8.h
---------------------------------------------------------------
#ifndef CHIP_8_H
#define CHIP_8_H
#include <stdint.h>
class Chip8 {
private:
uint16_t stack[16]; // Stack
uint16_t sp; // Stack pointer
uint8_t memory[4096]; // Memory (4k)
uint8_t V[16]; // V registers (V0-VF)
uint16_t pc; // Program counter
uint16_t opcode; // Current op code
uint16_t I; // Index register
uint8_t delay_timer; // Delay timer
uint8_t sound_timer; // Sound timer
void init();
public:
uint8_t gfx[64 * 32]; // Graphics buffer
uint8_t key[16]; // Keypad
bool drawFlag; // Indicates a draw has occurred
Chip8();
~Chip8();
void emulate_cycle(); // Emulate one cycle
bool load(unsigned char programma[],int size); // Load application
};
#endif // CHIP_8_H
---------------------------------------------------------------
#define CHIP_8_H
#include <stdint.h>
class Chip8 {
private:
uint16_t stack[16]; // Stack
uint16_t sp; // Stack pointer
uint8_t memory[4096]; // Memory (4k)
uint8_t V[16]; // V registers (V0-VF)
uint16_t pc; // Program counter
uint16_t opcode; // Current op code
uint16_t I; // Index register
uint8_t delay_timer; // Delay timer
uint8_t sound_timer; // Sound timer
void init();
public:
uint8_t gfx[64 * 32]; // Graphics buffer
uint8_t key[16]; // Keypad
bool drawFlag; // Indicates a draw has occurred
Chip8();
~Chip8();
void emulate_cycle(); // Emulate one cycle
bool load(unsigned char programma[],int size); // Load application
};
#endif // CHIP_8_H
---------------------------------------------------------------
chip8.cpp
---------------------------------------------------------------#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <random>
#include "time.h"
#include "chip8.h"
unsigned char 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
};
Chip8::Chip8() {}
Chip8::~Chip8() {}
// Initialise
void Chip8::init() {
pc = 0x200; // Set program counter to 0x200
opcode = 0; // Reset op code
I = 0; // Reset I
sp = 0; // Reset stack pointer
// Clear the display
for (int i = 0; i < 2048; ++i) {
gfx[i] = 0;
}
// Clear the stack, keypad, and V registers
for (int i = 0; i < 16; ++i) {
stack[i] = 0;
key[i] = 0;
V[i] = 0;
}
// Clear memory
for (int i = 0; i < 4096; ++i) {
memory[i] = 0;
}
// Load font set into memory
for (int i = 0; i < 80; ++i) {
memory[i] = chip8_fontset[i];
}
// Reset timers
delay_timer = 0;
sound_timer = 0;
// Seed rng
srand (time(NULL));
}
// Initialise and load ROM into memory
bool Chip8::load(unsigned char programma[],int size) {
// Initialise
init();
//long rom_size = sizeof(programma);
int rom_size = size;
// Copy buffer to memory
if ((4096-512) > rom_size){
for (int i = 0; i < rom_size; ++i) {
memory[i + 512] = (uint8_t)programma[i]; // Load into memory starting
// at 0x200 (=512)
}
}
else {
std::cerr << "ROM too large to fit in memory" << std::endl;
return false;
}
return true;
}
// Emulate one cycle
void Chip8::emulate_cycle() {
// Fetch op code
opcode = memory[pc] << 8 | memory[pc + 1]; // Op code is two bytes
switch(opcode & 0xF000){
// 00E_
case 0x0000:
switch (opcode & 0x000F) {
// 00E0 - Clear screen
case 0x0000:
for (int i = 0; i < 2048; ++i) {
gfx[i] = 0;
}
drawFlag = true;
pc+=2;
break;
// 00EE - Return from subroutine
case 0x000E:
--sp;
pc = stack[sp];
pc += 2;
break;
default:
printf("\nUnknown op code: %.4X\n", opcode);
exit(3);
}
break;
// 1NNN - Jumps to address NNN
case 0x1000:
pc = opcode & 0x0FFF;
break;
// 2NNN - Calls subroutine at NNN
case 0x2000:
stack[sp] = pc;
++sp;
pc = opcode & 0x0FFF;
break;
// 3XNN - Skips the next instruction if VX equals NN.
case 0x3000:
if (V[(opcode & 0x0F00) >> 8] == (opcode & 0x00FF))
pc += 4;
else
pc += 2;
break;
// 4XNN - Skips the next instruction if VX does not equal NN.
case 0x4000:
if (V[(opcode & 0x0F00) >> 8] != (opcode & 0x00FF))
pc += 4;
else
pc += 2;
break;
// 5XY0 - Skips the next instruction if VX equals VY.
case 0x5000:
if (V[(opcode & 0x0F00) >> 8] == V[(opcode & 0x00F0) >> 4])
pc += 4;
else
pc += 2;
break;
// 6XNN - Sets VX to NN.
case 0x6000:
V[(opcode & 0x0F00) >> 8] = opcode & 0x00FF;
pc += 2;
break;
// 7XNN - Adds NN to VX.
case 0x7000:
V[(opcode & 0x0F00) >> 8] += opcode & 0x00FF;
pc += 2;
break;
// 8XY_
case 0x8000:
switch (opcode & 0x000F) {
// 8XY0 - Sets VX to the value of VY.
case 0x0000:
V[(opcode & 0x0F00) >> 8] = V[(opcode & 0x00F0) >> 4];
pc += 2;
break;
// 8XY1 - Sets VX to (VX OR VY).
case 0x0001:
V[(opcode & 0x0F00) >> 8] |= V[(opcode & 0x00F0) >> 4];
pc += 2;
break;
// 8XY2 - Sets VX to (VX AND VY).
case 0x0002:
V[(opcode & 0x0F00) >> 8] &= V[(opcode & 0x00F0) >> 4];
pc += 2;
break;
// 8XY3 - Sets VX to (VX XOR VY).
case 0x0003:
V[(opcode & 0x0F00) >> 8] ^= V[(opcode & 0x00F0) >> 4];
pc += 2;
break;
// 8XY4 - Adds VY to VX. VF is set to 1 when there's a carry,
// and to 0 when there isn't.
case 0x0004:
V[(opcode & 0x0F00) >> 8] += V[(opcode & 0x00F0) >> 4];
if(V[(opcode & 0x00F0) >> 4] > (0xFF - V[(opcode & 0x0F00) >> 8]))
V[0xF] = 1; //carry
else
V[0xF] = 0;
pc += 2;
break;
// 8XY5 - VY is subtracted from VX. VF is set to 0 when
// there's a borrow, and 1 when there isn't.
case 0x0005:
if(V[(opcode & 0x00F0) >> 4] > V[(opcode & 0x0F00) >> 8])
V[0xF] = 0; // there is a borrow
else
V[0xF] = 1;
V[(opcode & 0x0F00) >> 8] -= V[(opcode & 0x00F0) >> 4];
pc += 2;
break;
// 0x8XY6 - Shifts VX right by one. VF is set to the value of
// the least significant bit of VX before the shift.
case 0x0006:
V[0xF] = V[(opcode & 0x0F00) >> 8] & 0x1;
V[(opcode & 0x0F00) >> 8] >>= 1;
pc += 2;
break;
// 0x8XY7: Sets VX to VY minus VX. VF is set to 0 when there's
// a borrow, and 1 when there isn't.
case 0x0007:
if(V[(opcode & 0x0F00) >> 8] > V[(opcode & 0x00F0) >> 4]) // VY-VX
V[0xF] = 0; // there is a borrow
else
V[0xF] = 1;
V[(opcode & 0x0F00) >> 8] = V[(opcode & 0x00F0) >> 4] - V[(opcode & 0x0F00) >> 8];
pc += 2;
break;
// 0x8XYE: Shifts VX left by one. VF is set to the value of
// the most significant bit of VX before the shift.
case 0x000E:
V[0xF] = V[(opcode & 0x0F00) >> 8] >> 7;
V[(opcode & 0x0F00) >> 8] <<= 1;
pc += 2;
break;
default:
printf("\nUnknown op code: %.4X\n", opcode);
exit(3);
}
break;
// 9XY0 - Skips the next instruction if VX doesn't equal VY.
case 0x9000:
if (V[(opcode & 0x0F00) >> 8] != V[(opcode & 0x00F0) >> 4])
pc += 4;
else
pc += 2;
break;
// ANNN - Sets I to the address NNN.
case 0xA000:
I = opcode & 0x0FFF;
pc += 2;
break;
// BNNN - Jumps to the address NNN plus V0.
case 0xB000:
pc = (opcode & 0x0FFF) + V[0];
break;
// CXNN - Sets VX to a random number, masked by NN.
case 0xC000:
V[(opcode & 0x0F00) >> 8] = (rand() % (0xFF + 1)) & (opcode & 0x00FF);
pc += 2;
break;
// DXYN: Draws a sprite at coordinate (VX, VY) that has a width of 8
// pixels and a height of N pixels.
// Each row of 8 pixels is read as bit-coded starting from memory
// location I;
// I value doesn't change after the execution of this instruction.
// VF is set to 1 if any screen pixels are flipped from set to unset
// when the sprite is drawn, and to 0 if that doesn't happen.
case 0xD000:
{
unsigned short x = V[(opcode & 0x0F00) >> 8];
unsigned short y = V[(opcode & 0x00F0) >> 4];
unsigned short height = opcode & 0x000F;
unsigned short pixel;
V[0xF] = 0;
for (int yline = 0; yline < height; yline++)
{
pixel = memory[I + yline];
for(int xline = 0; xline < 8; xline++)
{
if((pixel & (0x80 >> xline)) != 0)
{
if(gfx[(x + xline + ((y + yline) * 64))] == 1)
{
V[0xF] = 1;
}
gfx[x + xline + ((y + yline) * 64)] ^= 1;
}
}
}
drawFlag = true;
pc += 2;
}
break;
// EX__
case 0xE000:
switch (opcode & 0x00FF) {
// EX9E - Skips the next instruction if the key stored
// in VX is pressed.
case 0x009E:
if (key[V[(opcode & 0x0F00) >> 8]] != 0)
pc += 4;
else
pc += 2;
break;
// EXA1 - Skips the next instruction if the key stored
// in VX isn't pressed.
case 0x00A1:
if (key[V[(opcode & 0x0F00) >> 8]] == 0)
pc += 4;
else
pc += 2;
break;
default:
printf("\nUnknown op code: %.4X\n", opcode);
exit(3);
}
break;
// FX__
case 0xF000:
switch(opcode & 0x00FF)
{
// FX07 - Sets VX to the value of the delay timer
case 0x0007:
V[(opcode & 0x0F00) >> 8] = delay_timer;
pc += 2;
break;
// FX0A - A key press is awaited, and then stored in VX
case 0x000A:
{
bool key_pressed = false;
for(int i = 0; i < 16; ++i)
{
if(key[i] != 0)
{
V[(opcode & 0x0F00) >> 8] = i;
key_pressed = true;
}
}
// If no key is pressed, return and try again.
if(!key_pressed)
return;
pc += 2;
}
break;
// FX15 - Sets the delay timer to VX
case 0x0015:
delay_timer = V[(opcode & 0x0F00) >> 8];
pc += 2;
break;
// FX18 - Sets the sound timer to VX
case 0x0018:
sound_timer = V[(opcode & 0x0F00) >> 8];
pc += 2;
break;
// FX1E - Adds VX to I
case 0x001E:
// VF is set to 1 when range overflow (I+VX>0xFFF), and 0
// when there isn't.
if(I + V[(opcode & 0x0F00) >> 8] > 0xFFF)
V[0xF] = 1;
else
V[0xF] = 0;
I += V[(opcode & 0x0F00) >> 8];
pc += 2;
break;
// FX29 - Sets I to the location of the sprite for the
// character in VX. Characters 0-F (in hexadecimal) are
// represented by a 4x5 font
case 0x0029:
I = V[(opcode & 0x0F00) >> 8] * 0x5;
pc += 2;
break;
// FX33 - Stores the Binary-coded decimal representation of VX
// at the addresses I, I plus 1, and I plus 2
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] % 10;
pc += 2;
break;
// FX55 - Stores V0 to VX in memory starting at address I
case 0x0055:
for (int i = 0; i <= ((opcode & 0x0F00) >> 8); ++i)
memory[I + i] = V[i];
// On the original interpreter, when the
// operation is done, I = I + X + 1.
I += ((opcode & 0x0F00) >> 8) + 1;
pc += 2;
break;
case 0x0065:
for (int i = 0; i <= ((opcode & 0x0F00) >> 8); ++i)
V[i] = memory[I + i];
// On the original interpreter,
// when the operation is done, I = I + X + 1.
I += ((opcode & 0x0F00) >> 8) + 1;
pc += 2;
break;
default:
printf ("Unknown opcode [0xF000]: 0x%X\n", opcode);
}
break;
default:
printf("\nUnimplemented op code: %.4X\n", opcode);
exit(3);
}
// Update timers
if (delay_timer > 0)
--delay_timer;
if (sound_timer > 0)
if(sound_timer == 1);
// TODO: Implement sound
--sound_timer;
}
---------------------------------------------------------------
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