move parity computation to shared header

Author: davidly

djl_os.hxx

@@ -394,4 +394,21 @@ inline char printable( uint8_t x )
     } //wcslen
 #endif
 
+inline bool is_parity_even8( uint8_t x )
+{
+     // use popcnt if possible. It's not available on the Q9650 and other older Intel CPUs. use fallback code below instead if needed.
+
+    #if defined( __GNUC__ ) || defined( __clang__ )
+        return ( ! ( __builtin_popcount( x ) & 1 ) );
+    #elif defined( _MSC_VER )
+        return ( ! ( __popcnt16( x ) & 1 ) );
+    #elif defined( __aarch64__ )
+        return ( ! ( std::bitset<8>( x ).count() & 1 ) );
+    #else
+        x ^= ( x >> 4 );
+        x ^= ( x >> 2 );
+        x ^= ( x >> 1 );
+        return ! ( x & 1 );
+    #endif
+} //is_parity_even8
 

x80.cxx

@@ -175,16 +175,7 @@ static uint16_t pcword() { uint16_t r = mword( reg.pc ); reg.pc += 2; return r;
 static void pushword( uint16_t val ) { reg.sp -= 2; setmword( reg.sp, val ); }
 static uint16_t popword() {  uint16_t val = mword( reg.sp ); reg.sp += 2; return val; }
 
-bool is_parity_even( uint8_t x )
-{
-#if defined(_M_AMD64) && !defined(__GNUC__)
-    return ( ! ( __popcnt16( x ) & 1 ) ); // less portable, but faster
-#else
-    return ( ! ( std::bitset<8>( x ).count() & 1 ) );
-#endif
-} //is_parity_even
-
-void set_parity( uint8_t x ) { reg.fParityEven_Overflow = is_parity_even( x ); }
+void set_parity( uint8_t x ) { reg.fParityEven_Overflow = is_parity_even8( x ); }
 
 void set_sign_zero( uint8_t x )
 {