diff --git a/include/winnt.h b/include/winnt.h
index c80efee077d..9296a3dc555 100644
--- a/include/winnt.h
+++ b/include/winnt.h
@@ -6262,60 +6262,12 @@ typedef enum _PROCESS_MITIGATION_POLICY
     MaxProcessMitigationPolicy
 } PROCESS_MITIGATION_POLICY, *PPROCESS_MITIGATION_POLICY;
 
-#ifdef _MSC_VER
 
-BOOLEAN _BitScanForward(unsigned long*,unsigned long);
-BOOLEAN _BitScanReverse(unsigned long*,unsigned long);
-
-#pragma intrinsic(_BitScanForward)
-#pragma intrinsic(_BitScanReverse)
-
-static inline BOOLEAN BitScanForward(DWORD *index, DWORD mask)
-{
-    return _BitScanForward((unsigned long*)index, mask);
-}
-
-static inline BOOLEAN BitScanReverse(DWORD *index, DWORD mask)
-{
-    return _BitScanReverse((unsigned long*)index, mask);
-}
-
-#elif defined(__GNUC__) && ((__GNUC__ > 3) || ((__GNUC__ == 3) && (__GNUC_MINOR__ >= 3)))
-
-static inline BOOLEAN BitScanForward(DWORD *index, DWORD mask)
-{
-    *index = __builtin_ctz(mask);
-    return mask != 0;
-}
-
-static inline BOOLEAN BitScanReverse(DWORD *index, DWORD mask)
-{
-    *index = 31 - __builtin_clz(mask);
-    return mask != 0;
-}
-
-#else
-
-static inline BOOLEAN BitScanForward(DWORD *index, DWORD mask)
-{
-    unsigned int r = 0;
-    while (r < 31 && !(mask & (1 << r))) r++;
-    *index = r;
-    return mask != 0;
-}
-
-static inline BOOLEAN BitScanReverse(DWORD *index, DWORD mask)
-{
-    unsigned int r = 31;
-    while (r > 0 && !(mask & (1 << r))) r--;
-    *index = r;
-    return mask != 0;
-}
-
-#endif
-
-/* Interlocked functions */
+/* Intrinsic functions */
 
+#define BitScanForward _BitScanForward
+#define BitScanReverse _BitScanReverse
+#define InterlockedAdd _InlineInterlockedAdd
 #define InterlockedAnd _InterlockedAnd
 #define InterlockedCompareExchange _InterlockedCompareExchange
 #define InterlockedCompareExchange64 _InterlockedCompareExchange64
@@ -6328,9 +6280,12 @@ static inline BOOLEAN BitScanReverse(DWORD *index, DWORD mask)
 #define InterlockedIncrement _InterlockedIncrement
 #define InterlockedIncrement16 _InterlockedIncrement16
 #define InterlockedOr _InterlockedOr
+#define InterlockedXor _InterlockedXor
 
 #ifdef _MSC_VER
 
+#pragma intrinsic(_BitScanForward)
+#pragma intrinsic(_BitScanReverse)
 #pragma intrinsic(_InterlockedAnd)
 #pragma intrinsic(_InterlockedCompareExchange)
 #pragma intrinsic(_InterlockedCompareExchange64)
@@ -6341,7 +6296,10 @@ static inline BOOLEAN BitScanReverse(DWORD *index, DWORD mask)
 #pragma intrinsic(_InterlockedDecrement)
 #pragma intrinsic(_InterlockedDecrement16)
 #pragma intrinsic(_InterlockedOr)
+#pragma intrinsic(_InterlockedXor)
 
+BOOLEAN   _BitScanForward(unsigned long*,unsigned long);
+BOOLEAN   _BitScanReverse(unsigned long*,unsigned long);
 long      _InterlockedAnd(long volatile *,long);
 long      _InterlockedCompareExchange(long volatile*,long,long);
 long long _InterlockedCompareExchange64(long long volatile*,long long,long long);
@@ -6352,6 +6310,12 @@ long      _InterlockedExchangeAdd(long volatile*,long);
 long      _InterlockedIncrement(long volatile*);
 short     _InterlockedIncrement16(short volatile*);
 long      _InterlockedOr(long volatile *,long);
+long      _InterlockedXor(long volatile *,long);
+
+static FORCEINLINE long InterlockedAdd( long volatile *dest, long val )
+{
+    return InterlockedExchangeAdd( dest, val ) + val;
+}
 
 #if !defined(__i386__) || _MSC_VER >= 1600
 
@@ -6412,6 +6376,23 @@ static FORCEINLINE void MemoryBarrier(void)
 
 #elif defined(__GNUC__)
 
+static FORCEINLINE BOOLEAN WINAPI BitScanForward(DWORD *index, DWORD mask)
+{
+    *index = __builtin_ctz( mask );
+    return mask != 0;
+}
+
+static FORCEINLINE BOOLEAN WINAPI BitScanReverse(DWORD *index, DWORD mask)
+{
+    *index = 31 - __builtin_clz( mask );
+    return mask != 0;
+}
+
+static FORCEINLINE LONG WINAPI InterlockedAdd( LONG volatile *dest, LONG val )
+{
+    return __sync_add_and_fetch( dest, val );
+}
+
 static FORCEINLINE LONG WINAPI InterlockedAnd( LONG volatile *dest, LONG val )
 {
     return __sync_fetch_and_and( dest, val );
@@ -6491,6 +6472,11 @@ static FORCEINLINE LONG WINAPI InterlockedOr( LONG volatile *dest, LONG val )
     return __sync_fetch_and_or( dest, val );
 }
 
+static FORCEINLINE LONG WINAPI InterlockedXor( LONG volatile *dest, LONG val )
+{
+    return __sync_fetch_and_xor( dest, val );
+}
+
 static FORCEINLINE void MemoryBarrier(void)
 {
     __sync_synchronize();