Fetch completed, decode started

src/emulate.c

@@ -20,25 +20,90 @@ int *readFile(char *filename) {
 }
 
 int fetch(int *objectcode, int programCounter) { 
-  return objectcode[programCounter];
+  return objectcode[programCounter]; //Returns an instruction at the value of programCounter
 }
 
 void initialiseRegisters(int *registers) {
   for (int i = 0; i < 17; i++) {
-      registers[i] = 0;
+      registers[i] = 0; //Sets all the registers to 0
     }
 }
 
+/*void decode(int instruction, int programcounter) { //Decode started but not working yet
+  enum instrSet{dataProcess, mul, singleData, branch};
+  enum instrSet instrType;
+  if ((2^27 + 2^26) & instruction == 0) {
+    instrType = dataProcess;
+  }
+  
+  switch (instrType) {
+    case dataProcess:
+      decodeDataProcess(instruction, programcounter);
+    break;
+  }
+}/*
+
+/*void decodeDataProcess(int instruction, int pc, char* decodedData) {
+  int opcode = ((2^24 + 2^23 + 2^22 + 2^21) & instruction) / (2^21)
+  switch (opcode) {
+    case 0:
+    break;
+    case 1:
+    break;
+    case 2:
+    break;
+    case 3:
+    break;
+    case 4:
+    break;
+    case 8:
+    break;
+    case 9:
+    break;
+    case 10:
+    break;
+    case 12:
+    break;
+    case 13:
+    break;
+  
+  }
+}*/
+
+void startCycle(int *objectcode, int *registers) {
+  int pc = registers[15]; //pc takes the value of the program counter
+  if (pc == 0) {
+    fetch(objectcode, pc);
+    pc = pc + 4;
+  } else if (pc == 4) {
+    fetch(objectcode, pc/4);
+    decode(objectcode, (pc/4 - 1));
+    pc = pc + 4;
+  } else {
+    fetch(objectcode, pc/4);
+    decode(objectcode, (pc/4 - 1));
+    execute(objectcode, (pc/4 - 2));
+    pc = pc + 4;
+  }
+}
+
 int main(int argc, char **argv) {
   
   int registers[17];
   int *objectcode;
+  char *decodedData;
+  bool halt;
   
   assert(argc == 2);
   
   initialiseRegisters(&registers[0]);
   objectcode = readFile(argv[1]);
   
+  while (!halt) {
+  startCycle(objectCode, &registers[0]);
+  }
+  
+  
   printf("%d\n", fetch(objectcode, 0));
   
   free(objectcode);