implement simple ops

chip8.c

@@ -1,9 +1,22 @@
 // http://devernay.free.fr/hacks/chip8/C8TECH10.HTM
-#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 
+#define READ_INS()                                                             \
+  uint8_t low = c->memory[c->pc++];                                            \
+  uint8_t high = c->memory[c->pc++];                                           \
+  uint16_t ins = (low << 8) | high;                                            \
+  uint16_t nnn = ins & 0x0FFF;                                                 \
+  uint8_t n = ins & 0x000F;                                                    \
+  uint8_t x = (ins >> 8) & 0x0F;                                               \
+  uint8_t y = (ins >> 4) & 0x0F;                                               \
+  uint8_t kk = ins & 0x00FF
+
+#define BAD_INS()                                                              \
+  fprintf(stderr, "unrecognized instruction\n");                               \
+  exit(1)
+
 typedef struct CHIP8 {
   uint8_t *memory;
   uint16_t pc;
@@ -42,17 +55,9 @@ CHIP8 chip8_create() {
   return c;
 }
 
-void chip8_disassemble(CHIP8 *c, size_t size) {
+void chip8_disassemble(CHIP8 *c, size_t ins_count) {
-  for (size_t i = 0; i < size; i++) {
+  for (size_t i = 0; i < ins_count; i++) {
-    uint8_t low = c->memory[c->pc++];
+    READ_INS();
-    uint8_t high = c->memory[c->pc++];
-    uint16_t ins = (low << 8) | high;
-
-    uint16_t nnn = ins & 0x0FFF;
-    uint8_t n = ins & 0x000F;
-    uint8_t x = (ins >> 8) & 0x0F;
-    uint8_t y = (ins >> 4) & 0x0F;
-    uint8_t kk = ins & 0x00FF;
 
     switch ((ins >> 12) & 0xF) {
     case 0x0: {
@@ -64,29 +69,29 @@ void chip8_disassemble(CHIP8 *c, size_t size) {
         puts("RET");
         break;
       default:
-        printf("SYS %hd\n", nnn);
+        printf("SYS %u\n", nnn);
       }
     } break;
     case 0x1: {
-      printf("JP %hd\n", nnn);
+      printf("JP %u\n", nnn);
     } break;
     case 0x2: {
-      printf("CALL %hd\n", nnn);
+      printf("CALL %u\n", nnn);
     } break;
     case 0x3: {
-      printf("SE V%x, %hhd\n", x, kk);
+      printf("SE V%x, %u\n", x, kk);
     } break;
     case 0x4: {
-      printf("SNE V%x, %hhd\n", x, kk);
+      printf("SNE V%x, %u\n", x, kk);
     } break;
     case 0x5: {
       printf("SE V%x, V%x\n", x, y);
     } break;
     case 0x6: {
-      printf("LD V%x, %hhd\n", x, kk);
+      printf("LD V%x, %u\n", x, kk);
     } break;
     case 0x7: {
-      printf("ADD V%x, %hhd\n", x, kk);
+      printf("ADD V%x, %u\n", x, kk);
     } break;
     case 0x8: {
       switch (n) {
@@ -118,24 +123,23 @@ void chip8_disassemble(CHIP8 *c, size_t size) {
         printf("SHL V%x\n", x);
         break;
       default:
-        fprintf(stderr, "unrecognized instruction\n");
+        BAD_INS();
-        exit(1);
       }
     } break;
     case 0x9: {
       printf("SNE V%x, V%x\n", x, y);
     } break;
     case 0xA: {
-      printf("LD I, %hd\n", nnn);
+      printf("LD I, %u\n", nnn);
     } break;
     case 0xB: {
-      printf("JP V0, %hd\n", nnn);
+      printf("JP V0, %u\n", nnn);
     } break;
     case 0xC: {
-      printf("RND V%x, %hd\n", x, kk);
+      printf("RND V%x, %u\n", x, kk);
     } break;
     case 0xD: {
-      printf("DRW V%x, V%x, %hhd\n", x, y, n);
+      printf("DRW V%x, V%x, %u\n", x, y, n);
     } break;
     case 0xE: {
       switch (kk) {
@@ -146,8 +150,7 @@ void chip8_disassemble(CHIP8 *c, size_t size) {
         printf("SKNP V%x\n", x);
         break;
       default:
-        fprintf(stderr, "unrecognized instruction\n");
+        BAD_INS();
-        exit(1);
       }
     } break;
     case 0xF: {
@@ -180,28 +183,185 @@ void chip8_disassemble(CHIP8 *c, size_t size) {
         printf("LD V%x, [I]\n", x);
         break;
       default:
-        fprintf(stderr, "unrecognized instruction\n");
+        BAD_INS();
-        exit(1);
       }
     } break;
     default:
-      fprintf(stderr, "unrecognized instruction\n");
+      BAD_INS();
-      exit(1);
     }
   }
 }
 
+void chip8_execute(CHIP8 *c) {
+  while (1) {
+    READ_INS();
+
+    switch ((ins >> 12) & 0xF) {
+    case 0x0: {
+      switch (nnn) {
+      case 0x0E0:
+        puts("TODO: CLS");
+        break;
+      case 0x0EE:
+        c->pc = c->stack[c->sp];
+        c->sp--;
+        break;
+      default:
+        c->pc = nnn;
+      }
+    } break;
+    case 0x1: {
+      c->pc = nnn;
+    } break;
+    case 0x2: {
+      c->sp++;
+      c->stack[c->sp] = c->pc;
+      c->pc = nnn;
+    } break;
+    case 0x3: {
+      if (c->reg[x] == kk) {
+        c->pc += 2;
+      }
+    } break;
+    case 0x4: {
+      if (c->reg[x] != kk) {
+        c->pc += 2;
+      }
+    } break;
+    case 0x5: {
+      if (c->reg[x] == c->reg[y]) {
+        c->pc += 2;
+      }
+    } break;
+    case 0x6: {
+      c->reg[x] = kk;
+    } break;
+    case 0x7: {
+      c->reg[x] += kk;
+    } break;
+    case 0x8: {
+      switch (n) {
+      case 0x0:
+        c->reg[x] = c->reg[y];
+        break;
+      case 0x1:
+        c->reg[x] |= c->reg[y];
+        break;
+      case 0x2:
+        c->reg[x] &= c->reg[y];
+        break;
+      case 0x3:
+        c->reg[x] ^= c->reg[y];
+        break;
+      case 0x4:
+        printf("TODO: ADD V%x, V%x\n", x, y);
+        break;
+      case 0x5:
+        printf("TODO: SUB V%x, V%x\n", x, y);
+        break;
+      case 0x6:
+        printf("TODO: SHR V%x\n", x);
+        break;
+      case 0x7:
+        printf("TODO: SUBN V%x, V%x\n", x, y);
+        break;
+      case 0xE:
+        printf("TODO: SHL V%x\n", x);
+        break;
+      default:
+        BAD_INS();
+      }
+    } break;
+    case 0x9: {
+      if (c->reg[x] != c->reg[y]) {
+        c->pc += 2;
+      }
+    } break;
+    case 0xA: {
+      c->I = nnn;
+    } break;
+    case 0xB: {
+      c->pc = nnn + c->reg[0];
+    } break;
+    case 0xC: {
+      c->reg[x] = (rand() % 256) & kk;
+    } break;
+    case 0xD: {
+      printf("TODO: DRW V%x, V%x, %u\n", x, y, n);
+    } break;
+    case 0xE: {
+      switch (kk) {
+      case 0x9E:
+        printf("TODO: SKP V%x\n", x);
+        break;
+      case 0xA1:
+        printf("TODO: SKNP V%x\n", x);
+        break;
+      default:
+        BAD_INS();
+      }
+    } break;
+    case 0xF: {
+      switch (kk) {
+      case 0x07:
+        c->reg[x] = c->delay_timer;
+        break;
+      case 0x0A:
+        printf("TODO: LD V%x, K\n", x);
+        break;
+      case 0x15:
+        c->delay_timer = c->reg[x];
+        break;
+      case 0x18:
+        c->sound_timer = c->reg[x];
+        break;
+      case 0x1E:
+        c->I += c->reg[x];
+        break;
+      case 0x29:
+        printf("TODO: LD F, V%x\n", x);
+        break;
+      case 0x33:
+        c->memory[c->I] = c->reg[x] / 100;
+        c->memory[c->I + 1] = (c->reg[x] / 10) % 10;
+        c->memory[c->I + 2] = c->reg[x] % 10;
+        break;
+      case 0x55:
+        printf("TODO: LD [I], V%x\n", x);
+        break;
+      case 0x65:
+        printf("TODO: LD V%x, [I]\n", x);
+        break;
+      default:
+        BAD_INS();
+      }
+    } break;
+    default:
+      BAD_INS();
+    }
+  }
+}
+
+void chip8_free(CHIP8 c) { free(c.memory); }
+
 int main(int argc, char *argv[]) {
+  if (argc < 2) {
+    fprintf(stderr, "Usage: %s <path>\n", argv[0]);
+    return 1;
+  }
+
   CHIP8 c = chip8_create();
 
-  uint8_t buffer[100000];
+  uint8_t buffer[4000];
   FILE *f = fopen(argv[1], "rb");
-  size_t n = fread(buffer, 1, 100000, f);
+  size_t n = fread(buffer, 1, 4000, f);
   fclose(f);
 
   for (size_t i = 0; i < n; i++) {
     c.memory[0x200 + i] = buffer[i];
   }
 
-  chip8_disassemble(&c, n);
+  chip8_execute(&c);
+
+  chip8_free(c);
 }