Minor changes

src/main.c

@@ -2,12 +2,18 @@
 #include "mem.h"
 #include "vcpu.h"
 
+#include <stdio.h>
 int main(int argc, char *argv[])
 {
+  /* unsigned char byte=137; */
+  /* unsigned char u,t,h; */
+  /* VCPUDoubleDabble(byte,&u,&t,&h); */
+  /* printf("%d: %01d%01d%01d\n",byte,h,t,u); */
+  /* return 0; */
 
   // Initialize
   MemInit();
-  MemLoadROM("../roms/logo_chip8.ch8");
+  MemLoadROM("../roms/chip8-test-suite/3-corax+.ch8");
 
   ScreenInit(800,400);
   VCPUInit();

src/screen.c

@@ -15,7 +15,7 @@ void ScreenInit(int width, int height){
 
   SetTraceLogLevel(LOG_ERROR); // Disable anoying raylib logs
   InitWindow(width, height, "Chip-8 Emulator");
-  SetTargetFPS(80); // Set game to run at 60 frames-per-second
+  SetTargetFPS(200); // Set game to run at 60 frames-per-second
 }
 
 void ScreenClear() {

src/vcpu.c

@@ -26,83 +26,109 @@ void VCPUFetch(){
 void VCPUDecode(){
   State.X=(State.opcode>>8) & 0xF;
   State.Y=(State.opcode>>4) & 0xF;
-  State.N=State.opcode & 0xF;
+  State.N=State.opcode & 0x0F;
+  State.NN=State.opcode & 0xFF;
+  State.NNN=State.opcode & 0x0FFF;
+}
 
-  State.NN=State.Y;
-  State.NN=State.NN<<4;
-  State.NN=State.NN | State.N;
-
-  State.NNN=State.opcode&0x0FFF;
+void VCPUDoubleDabble(unsigned char x, unsigned char *u, unsigned char *t, unsigned char *h){
+  unsigned int bcd=x;
+  for(int i=0;i<8;i++){
+    bcd=bcd<<1;
+    unsigned char byte=bcd & 0xFF;
+    unsigned char units=(bcd>>8) & 0xF;
+    unsigned char tens=(bcd>>12) & 0xF;
+    unsigned char hundreds=(bcd>>16) & 0xF;
+    //printf("hundreds:%04b tens:%04b units:%04b byte:%08b\n",hundreds,tens,units,byte);
+    if(i<7){
+      if(units>4)
+        units+=3;
+      if(tens>4)
+        tens+=3;
+      if(hundreds>4)
+        hundreds+=3;
+    }
+    bcd = (hundreds<<16) | (tens << 12) | (units << 8) | byte;
+  }
+  *u=bcd>>8 & 0xF;
+  *t=bcd>>12 & 0xF;
+  *h=bcd>>16 & 0xF;
 }
 
 void VCPUExecute(){
-  //  VCPUDump();
+  VCPUDump();
   switch(State.opcode >> 12){
   case 0x0: // Clear screen or return from subroutine
-    if(State.N == 0){ // Clear screen
+    if(State.N == 0x0){ // Clear screen
       ScreenClear();
     }
-    else { // Return from subroutine
+    else if(State.N == 0xE) { // Return from subroutine
       State.PC=State.stack[State.S];
       State.S--;
     }
-    break
-      ;;
+    break;
+    
   case 0x1: // Jump
     State.PC=State.NNN;
-    break
-      ;;
+    break;
+    
   case 0x2: // Call
     State.S++;
     State.stack[State.S]=State.PC;
     State.PC=State.NNN;
-    break
-      ;;
+    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: // SE: VX, VY
-    if(State.V[State.X]==State.V[State.Y])
-      State.PC+=2;
+    if(State.N == 0){
+      if(State.V[State.X]==State.V[State.Y])
+        State.PC+=2;
+    }
     break;
-    ;;
+    
   case 0x6:
     State.V[State.X]=State.NN;
-    break
-      ;;
+    break;
+      
   case 0x7:
-    State.V[State.X]+=State.NN;
-    break
-      ;;
+    State.V[State.X]=State.V[State.X] + State.NN;
+    break;
+    
   case 0x8: // Register operations
     switch(State.N){
+    case 0x0: // VX = VY
+      State.V[State.X]=State.V[State.Y];
+      break;
+      
     case 0x1: // VX = VX OR VY
       State.V[State.X]=State.V[State.X] | State.V[State.Y];
       break;
-      ;;
+      
     case 0x2: // VX = VX AND VY
       State.V[State.X]=State.V[State.X] & State.V[State.Y];
       break;
-      ;;
+      
     case 0x3: // VX = VX XOR VY
       State.V[State.X]=State.V[State.X] ^ State.V[State.Y];
       break;
-      ;;
+      
     case 0x4: // VX = VX + VY
-      if(State.V[State.X] + State.V[State.Y] > 255)
+      if((State.V[State.X] + State.V[State.Y]) > 255)
         State.V[REG_FLAG]=1;
       else
         State.V[REG_FLAG]=0;
-      State.V[State.X]=(State.V[State.X] + State.V[State.Y]) & 0xFF;
+      State.V[State.X]=State.V[State.X] + State.V[State.Y];
       break;
-      ;;
+      
     case 0x5: // VX = VX - VY
       if(State.V[State.X] > State.V[State.Y])
         State.V[REG_FLAG]=1;
@@ -110,7 +136,7 @@ void VCPUExecute(){
         State.V[REG_FLAG]=0;
       State.V[State.X]=State.V[State.X] - State.V[State.Y];
       break;
-      ;;
+      
     case 0x6: // VX = VX SHR 1
       if(State.V[State.X] & 0x1 == 1)
         State.V[REG_FLAG]=1;
@@ -118,55 +144,57 @@ void VCPUExecute(){
         State.V[REG_FLAG]=0;
       State.V[State.X]=State.V[State.X] >> 1;
       break;
-      ;;
+      
     case 0x7: // VX = VY - VX
-      if(State.V[State.X] < State.V[State.Y])
+      if(State.V[State.Y] > State.V[State.X])
         State.V[REG_FLAG]=1;
       else
         State.V[REG_FLAG]=0;
       State.V[State.X]=State.V[State.Y] - State.V[State.X];
       break;
-      ;;
+      
     case 0xE: // VX = VX SHL 1
-      if(State.V[State.X] >> 15 == 1)
+      if(State.V[State.X] >> 7 == 1)
         State.V[REG_FLAG]=1;
       else
         State.V[REG_FLAG]=0;
       State.V[State.X]=State.V[State.X] << 1;
       break;
-      ;;
+      
     }    
-    break
-      ;;
-  case 0x9: // SNE: VX, VY
-    if(State.V[State.X]!=State.V[State.Y])
-      State.PC+=2;
     break;
-    ;;
+    
+  case 0x9: // SNE: VX, VY
+    if(State.N==0){
+      if(State.V[State.X]!=State.V[State.Y])
+        State.PC+=2;
+    }
+    break;
+    
   case 0xA:
     State.I=State.NNN;
-    break
-      ;;
+    break;
+    
   case 0xB:
     State.PC=State.V[0]+State.NNN;
-    break
-      ;;
+    break;
+    
   case 0xC:
     unsigned short n = rand() % 255 + 1;
     State.V[State.X]=n & State.NN;
-    break
-      ;;    
+    break;
+      
   case 0xD: // Draw a sprite
-    int X=State.V[State.X]%63;
-    int Y=State.V[State.Y]%31;
+    int X=State.V[State.X]&63;
+    int Y=State.V[State.Y]&31;
     State.V[REG_FLAG]=0; // Set flag to 0
-    int width,height;
+    int width, height;
     ScreenWH(&width,&height);
     for(char row=0;row<State.N;row++){
       // Stop if row out of screen
       if(Y+row>=height)
         break;
-      char sprite;
+      unsigned char sprite;
       MemRead(&sprite,1,State.I+row); // Load sprite
       // Draw sprite
       for(int shift=0;shift<8;shift++){
@@ -178,51 +206,56 @@ void VCPUExecute(){
       }
     }
     break;
-    ;;
+    
   case 0xE:
     // TODO
-    break;;
+    break;
+    
   case 0xF:
     switch(State.NN){
     case 0x07: // Get timer
       State.V[State.X]=State.DT;
       break;
-      ;;
+      
     case 0x0A:
       // TODO
       break;
-      ;;
+      
     case 0x15: // Set timer
       State.DT=State.V[State.X];
       break;
-      ;;
+      
     case 0x18: // Set sound timer
       State.ST=State.V[State.X];
       break;
-      ;;
+      
     case 0x1E: // I = I + VX
       State.I=State.I+State.V[State.X];
       break;
-      ;;
+      
     case 0x29:
       // TODO
       break;
-      ;;
+      
     case 0x33:
-      // TODO
+      unsigned char units, tens, hundreds;
+      VCPUDoubleDabble(State.V[State.X],&units,&tens,&hundreds);
+      MemCopy(&hundreds,1,State.I);
+      MemCopy(&tens,1,State.I+1);
+      MemCopy(&units,1,State.I+2);
+      //      printf("hundreds:%d tens:%d units:%d byte:%d\n",hundreds,tens,units,State.V[State.X]);
       break;
-      ;;
+      
     case 0x55:
       MemCopy(State.V,0xF,State.I);
       break;
-      ;;
+      
     case 0x65:
       MemRead(State.V,0xF,State.I);
       break;
-      ;;
+      
     }
     break;
-      ;;
   }
 }
 

src/vcpu.h

@@ -25,10 +25,10 @@ typedef struct VCPU_State {
 
   // Intruction (opcode + decoded fields)
   unsigned short opcode;
-  char X;
-  char Y;
-  char N;
-  char NN;
+  unsigned char X;
+  unsigned char Y;
+  unsigned char N;
+  unsigned char NN;
   unsigned short NNN;
 } VCPU_State;
 
@@ -36,4 +36,5 @@ void VCPUInit();
 void VCPUFetch();
 void VCPUDecode();
 void VCPUExecute();
+void VCPUDoubleDabble(unsigned char x, unsigned char *u, unsigned char *t, unsigned char *h);
 void VCPUDump();