Minor changes

1 files changed, 29 insertions, 2 deletions

diff --git a/src/vcpu.c b/src/vcpu.c
index f660dc3..ab7177c 100644
--- a/src/vcpu.c
+++ b/src/vcpu.c
@@ -35,14 +35,41 @@ void VCPUDecode(){
 void VCPUExecute(){
   //  VCPUDump();
   switch(State.opcode >> 12){
-  case 0x0: // Clear screen
-    ScreenClear();
+  case 0x0: // Clear screen or return from subroutine
+    if(State.N == 0){ // Clear screen
+      ScreenClear();
+    }
+    else { // Return from subroutine
+      State.PC=State.stack[State.S];
+      State.S--;
+    }
     break
       ;;
   case 0x1: // Jump
     State.PC=State.NNN;
     break
       ;;
+  case 0x2: // Call
+    State.S++;
+    State.stack[State.S]=State.PC;
+    State.PC=State.NNN;
+    break
+      ;;
+  case 0x3: // SE: VX, byte
+    if(State.V[State.X]==State.NN)
+      State.PC+=2;
+    break;
+    ;;
+  case 0x4: // SNE: VX, byte
+    if(State.V[State.X]!=State.NN)
+      State.PC+=2;
+    break;
+    ;;
+  case 0x5: // SNE: VX, VY
+    if(State.V[State.X]==State.V[State.Y])
+      State.PC+=2;
+    break;
+    ;;
   case 0x6:
     State.V[State.X]=State.NN;
     break