Minor changes

src/vcpu.c

@@ -2,35 +2,17 @@
 #include "mem.h"
 #include "screen.h"
 
-// Program Counter (16 bits but only 12 bits used (4096 memory addresses))
-unsigned short PC;
-
-// Index register (16 bits but only 12 bits used (4096 memory addresses))
-unsigned short I;
-
-// Stack register (16 bits)
-unsigned short S;
-
-// General purpose registers (8 bits each)
-// Note last one often used as a flag register
-unsigned char V[16];
-
-// Delay timer (8 bits)
-unsigned char DT;
-
-// Sound timer (8 bits)
-unsigned char ST;
 
 // Current VCPU state
 VCPU_State State;
 
 void VCPUInit(){
-  PC=ADDR_ROM;
+  State.PC=ADDR_ROM;
 }
 
 void VCPUFetch(){
-  MemRead((char *)&(State.opcode),2,PC);
+  MemRead((char *)&(State.opcode),2,State.PC);
-  PC+=2;
+  State.PC+=2;
 }
 
 void VCPUDecode(){
@@ -48,19 +30,19 @@ void VCPUExecute(){
     break
       ;;
   case 0x1:
-    PC=State.NNN;
+    State.PC=State.NNN;
     break
       ;;
   case 0x6:
-    V[State.X]=State.NN;
+    State.V[State.X]=State.NN;
     break
       ;;
   case 0x7:
-    V[State.X]+=State.NN;
+    State.V[State.X]+=State.NN;
     break
       ;;
   case 0xA:
-    I=State.NNN;
+    State.I=State.NNN;
     break
       ;;
 

src/vcpu.h

@@ -1,6 +1,26 @@
 #pragma once
 
 typedef struct VCPU_State {
+  // Program Counter (16 bits but only 12 bits used (4096 memory addresses))
+  unsigned short PC;
+
+  // Index register (16 bits but only 12 bits used (4096 memory addresses))
+  unsigned short I;
+
+  // Stack register (16 bits)
+  unsigned short S;
+
+  // General purpose registers (8 bits each)
+  // Note last one often used as a flag register
+  unsigned char V[16];
+
+  // Delay timer (8 bits)
+  unsigned char DT;
+
+  // Sound timer (8 bits)
+  unsigned char ST;
+
+  // Intruction (opcode + decoded fields)
   short opcode;
   char X;
   char Y;