Minor changes

src/vcpu.c

@@ -1,7 +1,7 @@
 #include "vcpu.h"
 #include "mem.h"
 #include "screen.h"
-
+#include <stdio.h>
 
 // Current VCPU state
 VCPU_State State;
@@ -11,7 +11,11 @@ void VCPUInit(){
 }
 
 void VCPUFetch(){
-  MemRead((char *)&(State.opcode),2,State.PC);
+  unsigned char byte[2];
+  MemRead(byte,2,State.PC); // Little indian to -1 no +1
+  State.opcode=byte[0];
+  State.opcode=State.opcode<<8;
+  State.opcode=State.opcode | byte[1];
   State.PC+=2;
 }
 
@@ -24,7 +28,7 @@ void VCPUDecode(){
 }
 
 void VCPUExecute(){
-  switch(State.opcode & 0xF){
+  switch(State.opcode >> 12){
   case 0x0:
     ScreenClear();
     break
@@ -45,6 +49,18 @@ void VCPUExecute(){
     State.I=State.NNN;
     break
       ;;
-
+  case 0xD:
+    int X=State.V[State.X]%63;
+    int Y=State.V[State.Y]%31;
+    State.V[0xF]=0; // Set flag to 0
+    for(char row=0;row<State.N;row++){
+      
+    }
+    break;
+    ;;
   }
 }
+
+void VCPUDump(){
+  printf("opcode: 0x%04x\n",State.opcode&0xFFFF);
+}