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#include <emulator.h>
int emulator_initialise(Emulator* emulator)
{
const uint8_t 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
};
//zero out the memory
memset(emulator, 0, sizeof(Emulator));
memcpy(emulator->memory + FONT_LOAD_LOCATION, font, sizeof(font));
emulator->is_on = 1;
pthread_t emulator_timers_thread_id;
pthread_create(&emulator_timers_thread_id, NULL, &emulator_timers_thread, emulator);
return 0;
}
int emulator_load_rom(Emulator* emulator, char* rom_name)
{
printf("load rom!: %s\n", rom_name);
FILE* rom = fopen(rom_name, "r");
if(rom == NULL)
{
perror("no rom file!\n");
return 1;
}
struct stat st;
fstat(fileno(rom), &st);
//rom loaded after 0x200 into memory
int bytes_read = fread(emulator->memory + GAME_LOAD_LOCATION, 1, st.st_size, rom);
fclose(rom);
if(bytes_read != st.st_size)
{
perror("doesnt cuadrar\n");
return 2;
}
emulator->pc = GAME_LOAD_LOCATION;
return 0;
}
int emulator_tick(Emulator* emulator)
{
uint16_t* pc = &emulator->pc;
uint16_t instr = (emulator->memory[*pc] << 8) | emulator->memory[*pc + 1];
*pc += 2;
uint8_t first_nibble = (instr >> 12) & 0xf;
uint8_t X = (instr & 0x0F00) >> 8; //second_nibble
uint8_t Y = (instr & 0x00F0) >> 4; //third_nibble
uint8_t N = (instr & 0x000F); //fourth_nibble
uint8_t NN = (instr & 0x00FF); //second_byte
uint16_t NNN = (instr & 0x0FFF); //last three nibbles
dbgprintf("instr: 0x%x\n", instr);
dbgprintf("A: 0x%x\nX: 0x%x\nY: 0x%x\nN: 0x%x\nNN: 0x%x\nNNN: 0x%x\n", first_nibble, X, Y, N, NN, NNN);
switch(first_nibble)
{
case 0x0:
switch(NNN)
{
case 0x000:
emulator_dump_registers(emulator);
exit(1); //stop executing when program over
case 0x0E0: //00E0: Clear screen
dbgprintf("CLEAR SCREEN!\n");
break;
}
break;
case 0x1:
dbgprintf("JUMP! (0x%x)\n", NNN);
emulator->pc = NNN;
break;
case 0x2:
break;
case 0x3:
break;
case 0x4:
break;
case 0x5:
break;
case 0x6:
dbgprintf("SET REGISTER VX! (0x%x)\n", NN);
emulator->regs.V[X] = NN;
break;
case 0x7:
dbgprintf("ADD VALUE TO REGISTER VX! (0x%x)\n", NN);
emulator->regs.V[X] += NN;
break;
case 0x8:
break;
case 0xA:
dbgprintf("SET INDEX REGISTER I! (0x%x)\n", NNN);
emulator->regs.I = NNN;
break;
case 0xB:
break;
case 0xC:
break;
case 0xD:
dbgprintf("DRAW!\n");
int x = emulator->regs.V[X] % 64;
int y = emulator->regs.V[Y] % 32;
emulator->regs.VF = 0;
for(int row = 0; row < N; ++row)
{
uint8_t pixels = emulator->memory[emulator->regs.I + row];
for(int offset = 0; offset < 8; ++offset)
{
if((pixels & (0x80 >> offset)) != 0)
{
if(emulator->display[x + offset][y + row] == 1)
emulator->regs.V[0xF] = 1;
emulator->display[x + offset][y + row] ^= 1;
}
}
}
emulator->draw_flag = 1;
break;
case 0xE:
break;
case 0xF:
break;
}
dbgprintf("\n");
return 0;
}
void* emulator_timers_thread(Emulator* emulator)
{
printf("STARTED TIMERS THREAD\n");
while(emulator->is_on)
{
if(emulator->delay_timer > 0)
--emulator->delay_timer;
if(emulator->sound_timer > 0)
--emulator->sound_timer;
usleep(1000000 / 60);
}
return NULL;
}
void emulator_dump_registers(Emulator* emulator)
{
printf("REGISTERS: \n");
printf("\tV0: 0x%x", emulator->regs.V0);
printf("\tV1: 0x%x", emulator->regs.V1);
printf("\tV2: 0x%x", emulator->regs.V2);
printf("\tV3: 0x%x", emulator->regs.V3);
printf("\tV4: 0x%x", emulator->regs.V4);
printf("\tV5: 0x%x", emulator->regs.V5);
printf("\tV6: 0x%x", emulator->regs.V6);
printf("\tV7: 0x%x", emulator->regs.V7);
printf("\tV8: 0x%x", emulator->regs.V8);
printf("\tV9: 0x%x", emulator->regs.V9);
printf("\tVA: 0x%x", emulator->regs.VA);
printf("\tVB: 0x%x", emulator->regs.VB);
printf("\tVC: 0x%x", emulator->regs.VC);
printf("\tVD: 0x%x", emulator->regs.VD);
printf("\tVE: 0x%x", emulator->regs.VE);
printf("\tVF: 0x%x", emulator->regs.VF);
printf("\tI: 0x%x", emulator->regs.I);
}
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