Initial commitHEADmaster

2 files changed, 657 insertions, 0 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..423fc57
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,7 @@
+cmake_minimum_required(VERSION 3.16)
+project(chip8 C)
+
+set(CMAKE_C_STANDARD 99)
+
+add_executable(chip8 main.c)
+target_link_libraries(chip8 SDL2)
\ No newline at end of file
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..7737fc6
--- /dev/null
+++ b/main.c
@@ -0,0 +1,650 @@
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <time.h>
+#include <SDL2/SDL.h>
+
+#define CHIP8_REG_MAX 16
+#define CHIP8_STACK_MAX 16
+
+#define T_DELAY 0
+#define T_SND 1
+
+SDL_Event event;
+SDL_Renderer *renderer;
+SDL_Window *window;
+const Uint8 *keyboard_state;
+SDL_Keycode keyboard_buf[2];
+int monitor_enable;
+
+static const uint8_t FONT_HEX[] = {
+        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
+};
+
+struct Timer {
+    uint16_t counter;
+    uint16_t freq;
+};
+
+struct Cpu {
+    uint16_t VF;
+    uint16_t I;
+    uint16_t PC;
+    uint8_t SP;
+    uint8_t V[16];
+    uint8_t RAM[0x1000];
+    uint16_t STACK[16];
+    uint16_t *DT;
+    uint16_t *ST;
+    struct Timer DEV[2];
+};
+
+struct Instruction {
+    uint8_t opcode;
+    uint16_t operand;
+};
+
+struct Instruction parse_data(uint16_t data) {
+    struct Instruction instruction;
+    instruction.opcode = data >> 12;
+    instruction.operand = data & 0xfff;
+    return instruction;
+}
+
+int timer_update(struct Timer *timer) {
+    if (timer->counter > 0) {
+        timer->counter--;
+    }
+    return timer->counter;
+}
+
+void clear_screen() {
+    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
+    SDL_RenderClear(renderer);
+    SDL_SetRenderDrawColor(renderer, 255, 255, 255, 0);
+    SDL_RenderPresent(renderer);
+}
+
+void sprite_draw(struct Cpu *cpu, uint8_t x, uint8_t y, uint8_t n) {
+    uint8_t data;
+    for (int i = 0; i < n; i++) {
+        data = cpu->RAM[cpu->I + i];
+        for (int j = 8; j > 0; j--) {
+            if (data & 1) {
+                SDL_RenderDrawPoint(renderer, cpu->V[x] + j, cpu->V[y] + i);
+            }
+            data >>= 1;
+        }
+    }
+}
+
+void get_keypress() {
+    keyboard_buf[0] = event.key.keysym.sym;
+    keyboard_buf[1] = '\0';
+}
+
+void do_disassemble(struct Cpu *cpu, struct Instruction *inst) {
+    uint8_t x, y, n, kk;
+    uint16_t addr;
+
+    x = inst->operand >> 8;
+    y = (inst->operand & 0x0F0) >> 4;
+    n = inst->operand & 0x0F;
+    kk = inst->operand & 0xFF;
+    addr = inst->operand;
+
+    printf("%04X   ", inst->opcode << 12 |  inst->operand);
+
+    if (inst->opcode == 0 && inst->operand == 0xE0) {
+        // clear screen
+        printf("CLR\n");
+    } else if (inst->opcode == 0 && inst->operand == 0xEE) {
+        // return from subroutine
+        printf("RET\n");
+    } else if (inst->opcode == 0) {
+        printf("SYS %04X\n", inst->operand);
+        //printf("NOP\n", inst->operand);
+    } else if (inst->opcode == 1) {
+        // jump to operand address
+        printf("JP %04X\n", inst->operand);
+    } else if (inst->opcode == 2) {
+        // call subroutine at operand address
+        // inc stack, insert current PC, PC set to operand address
+        printf("CALL %04X\n", inst->operand);
+    } else if (inst->opcode == 3) {
+        // skip if Vx = kk
+        printf("SE V%u, %02X\n", x, kk);
+    } else if (inst->opcode == 4) {
+        // skip if Vx != kk
+        printf("SNE V%u, %02X\n", x, kk);
+    } else if (inst->opcode == 5) {
+        // skip if Vx == Vy
+        printf("SE V%u, V%u\n", x, y);
+    } else if (inst->opcode == 6) {
+        // set Vx = kk
+        printf("LD V%u, %02x\n", x, kk);
+    } else if (inst->opcode == 7) {
+        // set Vx = Vx + kk
+        printf("ADD V%u, %02x\n", x, kk);
+    } else if (inst->opcode == 8 && (inst->operand & 0xF) == 0) {
+        // set Vx = Vy
+        printf("LD V%u, V%u\n", x, y);
+    } else if (inst->opcode == 8 && (inst->operand & 0xF) == 1) {
+        // set Vx |= Vy
+        printf("OR V%u, V%u\n", x, y);
+    } else if (inst->opcode == 8 && (inst->operand & 0xF) == 2) {
+        // set Vx &= Vy
+        printf("AND V%u, V%u\n", x, y);
+    } else if (inst->opcode == 8 && (inst->operand & 0xF) == 3) {
+        // set Vx ^= Vy
+        printf("XOR V%u, V%u\n", x, y);
+    } else if (inst->opcode == 8 && (inst->operand & 0xF) == 4) {
+        // set Vx += Vy
+        printf("ADD V%u, V%u\n", x, y);
+    } else if (inst->opcode == 8 && (inst->operand & 0xF) == 5) {
+        // set Vx -= Vy
+        printf("SUB V%u, V%u\n", x, y);
+    } else if (inst->opcode == 8 && (inst->operand & 0xF) == 6) {
+        // set Vx >> 1
+        printf("SHR V%u\n", x);
+    } else if (inst->opcode == 8 && (inst->operand & 0xF) == 7) {
+        // set Vx = Vy - Vx (VF = NOT)
+        printf("SUBN V%u, V%u\n", x, y);
+    } else if (inst->opcode == 8 && (inst->operand & 0xF) == 0xE) {
+        // set Vx << 1
+        printf("SHL V%u\n", x);
+    } else if (inst->opcode == 9 && (inst->operand & 0xF) == 0) {
+        // set Vx != Vy
+        printf("SNE V%u, V%u\n", x, y);
+    } else if (inst->opcode == 0xA) {
+        // set I = operand address
+        printf("LD I, %03X\n", addr);
+    } else if (inst->opcode == 0xB) {
+        // jump to operand address + V0
+        printf("JP V0, %03X\n", addr);
+    } else if (inst->opcode == 0xC) {
+        // Vx = random byte and kk
+        printf("RND V%u, %03X\n", x, kk);
+    } else if (inst->opcode == 0xD) {
+        // display sprite
+        printf("DRW V%u, V%u, %01X\n", x, y, n);
+    } else if (inst->opcode == 0xE && (inst->operand & 0xFF) == 0x9E) {
+        // skip if key of value Vx is pressed
+        printf("SKP V%u\n", x);
+    } else if (inst->opcode == 0xE && (inst->operand & 0xFF) == 0xA1) {
+        // skip if key with value Vx is not pressed
+        printf("SKNP V%u\n", x);
+    } else if (inst->opcode == 0xF && inst->operand != 0) {
+        if ((inst->operand & 0xFF) == 0x7) {
+            // set Vx = DT
+            printf("LD V%u, DT\n", x);
+        } else if ((inst->operand & 0xFF) == 0xA) {
+            // wait for key, Vx = key
+            printf("LD V%u, K\n", x);
+        } else if ((inst->operand & 0xFF) == 0x15) {
+            // set DT = Vx
+            printf("LD DT, V%u\n", x);
+        } else if ((inst->operand & 0xFF) == 0x18) {
+            // set ST = Vx
+            printf("LD ST, V%u\n", x);
+        } else if ((inst->operand & 0xFF) == 0x1E) {
+            // set I = I + Vx
+            printf("ADD I, V%u\n", x);
+        } else if ((inst->operand & 0xFF) == 0x29) {
+            // set I = address of sprite for digit Vx
+            printf("LD F, V%u\n", x);
+        } else if ((inst->operand & 0xFF) == 0x33) {
+            // store BCD of Vx in I, I+1, I+2
+            printf("LD B, V%u\n", x);
+        } else if ((inst->operand & 0xFF) == 0x55) {
+            // store V0 ~ Vx starting at address I
+            printf("LD [I], V%u\n", x);
+        } else if ((inst->operand & 0xFF) == 0x65) {
+            // read V0 ~ Vx from address I
+            printf("LD V%u, [I]\n", x);
+        }
+    } else {
+        printf("invalid opcode: %01X%03X\n", inst->opcode, inst->operand);
+        exit(1);
+    }
+}
+void do_operation(struct Cpu *cpu, struct Instruction *inst) {
+    uint8_t x, y, n, kk;
+    uint16_t addr;
+
+    x = inst->operand >> 8;
+    y = (inst->operand & 0x0F0) >> 4;
+    n = inst->operand & 0x0F;
+    kk = inst->operand & 0xFF;
+    addr = inst->operand & 0xFFF;
+
+    cpu->PC += 2;
+
+    if (inst->opcode == 0 && inst->operand == 0xE0) {
+        // clear screen
+        clear_screen();
+    } else if (inst->opcode == 0 && inst->operand == 0xEE) {
+        // return from subroutine
+        cpu->PC = cpu->STACK[--cpu->SP];
+    } else if (inst->opcode == 0) {
+        cpu->PC = addr;
+    } else if (inst->opcode == 1) {
+        // jump to operand address
+        cpu->PC = addr;
+    } else if (inst->opcode == 2) {
+        // call subroutine at operand address
+        // inc stack, insert current PC, PC set to operand address
+        cpu->STACK[cpu->SP] = cpu->PC;
+        cpu->SP++;
+        cpu->PC = addr;
+    } else if (inst->opcode == 3) {
+        // skip if Vx = kk
+        if (cpu->V[x] == kk) {
+            cpu->PC += 2;
+        }
+    } else if (inst->opcode == 4) {
+        // skip if Vx != kk
+        if (cpu->V[x] != kk) {
+            cpu->PC += 2;
+        }
+    } else if (inst->opcode == 5) {
+        // skip if Vx == Vy
+        if (cpu->V[x] == cpu->V[y]) {
+            cpu->PC += 2;
+        }
+    } else if (inst->opcode == 6) {
+        // set Vx = kk
+        cpu->V[x] = kk;
+    } else if (inst->opcode == 7) {
+        // set Vx = Vx + kk
+        cpu->V[x] += kk;
+    } else if (inst->opcode == 8) {
+        if ((inst->operand & 0xF) == 0) {
+            // set Vx = Vy
+            cpu->V[x] = cpu->V[y];
+        } else if ((inst->operand & 0xF) == 1) {
+            // set Vx |= Vy
+            cpu->V[x] |= cpu->V[y];
+        } else if ((inst->operand & 0xF) == 2) {
+            // set Vx &= Vy
+            cpu->V[x] &= cpu->V[y];
+        } else if ((inst->operand & 0xF) == 3) {
+            // set Vx ^= Vy
+            cpu->V[x] ^= cpu->V[y];
+        } else if ((inst->operand & 0xF) == 4) {
+            // set Vx += Vy
+            cpu->V[x] += cpu->V[y];
+        } else if ((inst->operand & 0xF) == 5) {
+            // set Vx -= Vy
+            cpu->V[x] -= cpu->V[y];
+        } else if ((inst->operand & 0xF) == 6) {
+            // set Vx >> 1
+            cpu->VF = cpu->V[y] & 1;
+            cpu->V[x] >>= 1;
+        } else if ((inst->operand & 0xF) == 7) {
+            // set Vx = Vy - Vx (VF = NOT)
+            cpu->VF = cpu->V[y] > cpu->V[x];
+            cpu->V[x] = cpu->V[y] - cpu->V[x];
+        } else if ((inst->operand & 0xF) == 0xE) {
+            // set Vx << 1
+            cpu->VF = cpu->V[x] & 0x80;
+            cpu->V[x] <<= 1;
+        }
+    } else if (inst->opcode == 9) {
+        // set Vx != Vy
+        if (cpu->V[x] != cpu->V[y]) {
+            cpu->PC += 2;
+        }
+    } else if (inst->opcode == 0xA) {
+        // set I = operand address
+        cpu->I = addr & 0x0fff;
+    } else if (inst->opcode == 0xB) {
+        // jump to operand address + V0
+        cpu->PC = addr + cpu->V[0];
+    } else if (inst->opcode == 0xC) {
+        // Vx = random byte and kk
+        cpu->V[x] = (uint8_t)rand() & kk;
+    } else if (inst->opcode == 0xD) {
+        // display sprite
+        sprite_draw(cpu, x, y, n);
+    } else if (inst->opcode == 0xE && (inst->operand & 0xFF) == 0x9E) {
+        // skip if key of value Vx is pressed
+        if (cpu->V[x] == keyboard_buf[0]) {
+            cpu->PC += 2;
+        }
+    } else if (inst->opcode == 0xE && (inst->operand & 0xFF) == 0xA1) {
+        // skip if key with value Vx is not pressed
+        if (cpu->V[x] != keyboard_buf[0]) {
+            cpu->PC += 2;
+        }
+    } else if (inst->opcode == 0xF && inst->operand != 0) {
+        if ((inst->operand & 0xFF) == 0x7) {
+            // set Vx = DT
+            cpu->V[x] = *cpu->DT;
+        } else if ((inst->operand & 0xFF) == 0xA) {
+            // wait for key, Vx = key
+            cpu->V[x] = keyboard_buf[0];
+        } else if ((inst->operand & 0xFF) == 0x15) {
+            // set DT = Vx
+            *cpu->DT = cpu->V[x];
+        } else if ((inst->operand & 0xFF) == 0x18) {
+            // set ST = Vx
+            *cpu->ST = cpu->V[x];
+        } else if ((inst->operand & 0xFF) == 0x1E) {
+            // set I = I + Vx
+            cpu->I += cpu->V[x];
+        } else if ((inst->operand & 0xFF) == 0x29) {
+            // set I = address of sprite for digit Vx
+            cpu->I = cpu->V[x] * 5;
+        } else if ((inst->operand & 0xFF) == 0x33) {
+            // store BCD of Vx in I, I+1, I+2
+            char num[4];
+            sprintf(num, "%03u", cpu->V[x]);
+            printf("BCD: %s\n", num);
+            cpu->RAM[cpu->I] = num[0] - '0';
+            cpu->RAM[cpu->I + 1] = num[1] - '0';
+            cpu->RAM[cpu->I + 2] = num[2] - '0';
+        } else if ((inst->operand & 0xFF) == 0x55) {
+            // store V0 ~ Vx starting at address I
+            for (int i = 0; i <= x; i++) {
+                cpu->RAM[cpu->I + i] = cpu->V[i];
+            }
+        } else if ((inst->operand & 0xFF) == 0x65) {
+            // read V0 ~ Vx from address I
+            for (int i = 0; i <= x; i++) {
+                cpu->V[i] = cpu->RAM[cpu->I + i];
+            }
+        }
+    } else {
+        printf("invalid opcode: %01X%03X\n", inst->opcode, inst->operand);
+        exit(1);
+    }
+}
+
+size_t load_file_at(struct Cpu *cpu, const char *filename, uint16_t offset) {
+    FILE *fp;
+    char buf[10];
+    size_t bytes;
+    size_t bytes_read;
+    size_t i;
+
+    fp = fopen(filename, "r");
+    if (fp == NULL) {
+        perror(filename);
+        exit(1);
+    }
+
+    memset(buf, '\0', 10);
+
+    i = 0;
+    while (fread(&buf, sizeof(char), 1, fp) > 0) {
+        cpu->RAM[offset + i] = buf[0];
+        i++;
+    }
+    fclose(fp);
+    return i;
+}
+
+void cpu_info(struct Cpu *cpu) {
+    printf("PC=%04X, ", cpu->PC);
+    printf("SP=%02X ", cpu->SP);
+    printf("I=%04X, ", cpu->I);
+    printf("DT=%04X, ", *cpu->DT);
+    printf("ST=%04X, ", *cpu->ST);
+    printf("VF=%u ", cpu->VF);
+    printf("KB=%02X\n", keyboard_buf[0]);
+
+    int c = 0;
+    for (int i = 0; i < CHIP8_REG_MAX; i++) {
+        if (c == 4) {
+            printf("\n");
+            c = 0;
+        }
+        printf("V[%02d]=%02x%c ", i, cpu->V[i], (i == CHIP8_REG_MAX - 1) ? ' ' : ',');
+        c++;
+    }
+    printf("\n");
+
+    printf("I[0:%u]: ", CHIP8_REG_MAX);
+    for (int i = 0; i < CHIP8_REG_MAX; i++) {
+        if (cpu->I + i > sizeof(cpu->RAM)) {
+            break;
+        }
+        printf("%02X ", cpu->RAM[cpu->I + i]);
+    }
+    printf("\n");
+}
+
+void cpu_reset(struct Cpu *cpu) {
+    memset(cpu->V, 0, sizeof(cpu->V));
+    memset(cpu->DEV, 0, sizeof(cpu->DEV));
+    cpu->DT = &cpu->DEV[T_DELAY].counter;
+    cpu->ST = &cpu->DEV[T_SND].counter;
+    cpu->PC = 0x200;
+    cpu->I = 0x0000;
+    cpu->SP = 0x00;
+    cpu->VF = 0x00;
+    for (int i = 0; i < sizeof(FONT_HEX) / (sizeof(uint8_t)); i++) {
+        cpu->RAM[i] = FONT_HEX[i];
+    }
+    memset(keyboard_buf, '\0', 2);
+}
+
+static uint16_t breakpoints[255];
+static uint16_t watchpoints[255];
+int monitor(struct Cpu *cpu) {
+    static int last_bp = 0;
+    static int last_wp = 0;
+    static int ignore = 0;
+    char input[255];
+    char *iptr = input;
+    uint16_t addr, opcode, count;
+    uint16_t pc;
+
+    for (int i = 0; i <= last_bp; i++) {
+        if (cpu->PC == breakpoints[i]) {
+            printf("breakpoint #%u reached\n", i);
+            ignore = 0;
+        }
+    }
+
+    for (int i = 0; i <= last_wp; i++) {
+        opcode = cpu->RAM[cpu->PC] << 8 | cpu->RAM[cpu->PC + 1];
+        if (opcode == watchpoints[i]) {
+            printf("watchpoint #%u reached\n", i);
+            ignore = 0;
+        }
+    }
+
+    if (ignore) {
+        return 0;
+    }
+
+    memset(input, '\0', sizeof(input));
+    pc = cpu->PC;
+
+    printf("%04XH> ", cpu->PC);
+    iptr = fgets(input, sizeof(input) - 1, stdin);
+    if (iptr == NULL) {
+        cpu->PC = pc;
+        return 0;
+    }
+
+
+    switch (input[0]) {
+        case 'g':
+            cpu->PC = strtol(&input[1], NULL, 16);
+            return -1;
+        case 'n':
+            // next instruction
+            break;
+        case 'x':
+            count = strtol(&input[1], NULL, 16);
+            addr = strtol(&input[3], NULL, 16);
+            printf("%02X: ", addr);
+            for (int i = 0; i < count; i++) {
+                printf("%02X ", cpu->RAM[addr + count]);
+            }
+            printf("\n");
+            cpu->PC = pc;
+            return -1;
+        case 'b':
+            addr = strtol(&input[1], NULL, 16);
+            printf("breakpoint #%u: %04x\n", last_bp, addr);
+            breakpoints[last_bp] = addr;
+            last_bp++;
+            return -1;
+        case 'w':
+            opcode = strtol(&input[1], NULL, 16);
+            printf("watchpoint #%u: %04x\n", last_wp, opcode);
+            watchpoints[last_wp] = opcode;
+            last_wp++;
+            return -1;
+        case 'r':
+            printf("running...\n");
+            ignore = 1;
+            break;
+        case 'R':
+            printf("reset CPU...\n");
+            clear_screen();
+            cpu_reset(cpu);
+            return -1;
+        case 'm':
+            addr = strtol(&input[1], NULL, 16);
+            count = strtol(&input[3], NULL, 16);
+
+            if (count < 16) {
+                count = 16;
+            }
+
+            for (int i = addr, c = 0; i < addr + count; i++) {
+                if (c == 0) {
+                    printf("%04X: ", addr + i);
+                } else if (c == 7) {
+                    printf(" ");
+                } else if (c == 15) {
+                    c = 0;
+                    printf("\n");
+                    continue;
+                }
+                printf("%02X ", cpu->RAM[i]);
+                c++;
+            }
+            printf("\n\n");
+            return -1;
+        case 'q':
+            printf("quitting...");
+            monitor_enable = 0;
+            return -1;
+        default:
+            cpu->PC = pc;
+            return -1;
+    }
+    return 0;
+}
+
+int main(int argc, char *argv[]) {
+    struct Cpu cpu;
+    struct Instruction instruction;
+    char *tmp = NULL;
+    char program[PATH_MAX];
+    monitor_enable = 0;
+
+    if ((tmp = strrchr(argv[0], '/')) != NULL) {
+        tmp ++;
+        strcpy(program, tmp);
+    }
+
+    if (argc < 2) {
+        printf("usage: %s ROMFILE\n", program);
+        exit(1);
+    }
+
+    memset(&instruction, 0, sizeof(struct Instruction));
+
+    srand((unsigned)time(NULL));
+    SDL_Init(SDL_INIT_VIDEO);
+    SDL_CreateWindowAndRenderer(648, 325, SDL_WINDOW_ALLOW_HIGHDPI, &window, &renderer);
+    //SDL_SetRenderDrawColor(renderer, 255, 255, 255, 0);
+    SDL_RenderSetScale(renderer, 10.0f, 10.0f);
+    SDL_RenderPresent(renderer);
+
+    clear_screen();
+    cpu_reset(&cpu);
+
+    size_t rom_size;
+    rom_size = load_file_at(&cpu, argv[1], 0x200);
+    printf("ROM size: %zu\n", rom_size);
+
+    keyboard_state = SDL_GetKeyboardState(NULL);
+
+    int done = 0;
+    while (!done) {
+        while (SDL_PollEvent(&event)) {
+            switch (event.type) {
+                case SDL_QUIT:
+                    done = 1;
+                    break;
+                case SDL_KEYDOWN:
+                    switch (event.key.keysym.sym) {
+                        case SDLK_ESCAPE:
+                            done = 1;
+                            break;
+                        case SDLK_F1:
+                            monitor_enable = 1;
+                            break;
+                        default:
+                            keyboard_buf[0] = event.key.keysym.sym;
+                            break;
+                    }
+                default:
+                    break;
+            }
+        }
+
+        timer_update(&cpu.DEV[T_DELAY]);
+        timer_update(&cpu.DEV[T_SND]);
+
+        instruction = parse_data(cpu.RAM[cpu.PC] << 8 | cpu.RAM[cpu.PC + 1]);
+        do_disassemble(&cpu, &instruction);
+        do_operation(&cpu, &instruction);
+        printf("\n");
+        cpu_info(&cpu);
+        printf("\n");
+
+        if (cpu.SP > CHIP8_STACK_MAX) {
+            fprintf(stderr, "FAULT: stack overflow\n");
+            break;
+        }
+
+        SDL_RenderPresent(renderer);
+
+        SDL_Delay(10);
+        if (monitor_enable != 0 && monitor(&cpu) < 0) {
+            continue;
+        }
+        keyboard_buf[0] = '\0';
+    }
+
+    SDL_DestroyRenderer(renderer);
+    SDL_DestroyWindow(window);
+    SDL_Quit();
+    return 0;
+}