Add new opcode test ROM and implement VF reset quirk

README.md

@@ -121,6 +121,7 @@ Also includes flags for disabling specific S-CHIP "quirks" (which are all enable
 `-6` Allow sprite wrapping  
 `-7` Disable collision enumeration  
 `-8` Disable collision check with bottom of screen
+`-9` Enable VF reset on logical OR, AND, XOR
 
 
 ## Controls

include/chip8.h

@@ -29,7 +29,7 @@
 #define NUM_KEYS 16
 #define NUM_REGISTERS 16
 #define NUM_USER_FLAGS 16
-#define NUM_QUIRKS 9
+#define NUM_QUIRKS 10
 #define NUM_BITPLANES 3
 #define NUM_FONT_BYTES 80
 #define NUM_BIG_FONT_BYTES 160

src/chip8.c

@@ -452,21 +452,42 @@ void chip8_execute(CHIP8 *chip8)
             break;
 
         /* OR Vx, Vy (8xy1)
-           Set Vx = Vx OR Vy. */
+           Set Vx = Vx OR Vy.
+           Legacy: Set VF = 0.
+           S-CHIP: Leave VF alone. */
         case 0x01:
             chip8->V[x] |= chip8->V[y];
+
+            if (!chip8->quirks[9])
+            {
+                chip8->V[0x0F] = 0;
+            }
             break;
 
         /* AND Vx, Vy (8xy2)
-           Set Vx = Vx AND Vy. */
+           Set Vx = Vx AND Vy.
+           Legacy: Set VF = 0.
+           S-CHIP: Leave VF alone. */
         case 0x02:
             chip8->V[x] &= chip8->V[y];
+            
+            if (!chip8->quirks[9])
+            {
+                chip8->V[0x0F] = 0;
+            }
             break;
 
         /* XOR Vx, Vy (8xy3)
-           Set Vx = Vx XOR Vy. */
+           Set Vx = Vx XOR Vy.
+           Legacy: Set VF = 0.
+           S-CHIP: Leave VF alone. */
         case 0x03:
             chip8->V[x] ^= chip8->V[y];
+            
+            if (!chip8->quirks[9])
+            {
+                chip8->V[0x0F] = 0;
+            }
             break;
 
         /* ADD Vx, Vy (8xy4)

src/main.c

@@ -38,7 +38,7 @@ unsigned long cpu_freq = CPU_FREQ_DEFAULT;
 unsigned long timer_freq = TIMER_FREQ_DEFAULT;
 unsigned long refresh_freq = REFRESH_FREQ_DEFAULT;
 bool play_sound = false;
-bool quirks[NUM_QUIRKS] = {1, 1, 1, 1, 1, 1, 1, 1, 1};
+bool quirks[NUM_QUIRKS] = {1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
 bool load_dmp = false;
 
 // Color/Display
@@ -285,6 +285,7 @@ bool handle_args(int argc, char **argv)
             case '6':
             case '7':
             case '8':
+            case '9':
                 quirks[opt - '0'] = false;
                 break;