Adding compiler intrinsics implementation for bit operations

src/bitops.c

@@ -9,34 +9,61 @@
 
 u32 rotl32 (const u32 a, const u32 n)
 {
+  #if defined (_MSC_VER)
+  return _rotl (a, n);
+  #else
   return ((a << n) | (a >> (32 - n)));
+  #endif
 }
 
 u32 rotr32 (const u32 a, const u32 n)
 {
+  #if defined (_MSC_VER)
+  return _rotr (a, n);
+  #else
   return ((a >> n) | (a << (32 - n)));
+  #endif
 }
 
 u64 rotl64 (const u64 a, const u64 n)
 {
+  #if defined (_MSC_VER)
+  return _rotl64 (a, n);
+  #else
   return ((a << n) | (a >> (64 - n)));
+  #endif
 }
 
 u64 rotr64 (const u64 a, const u64 n)
 {
+  #if defined (_MSC_VER)
+  return _rotr64 (a, n);
+  #else
   return ((a >> n) | (a << (64 - n)));
+  #endif
 }
 
 u32 byte_swap_32 (const u32 n)
 {
+  #if defined (_MSC_VER)
+  return _byteswap_ulong (n);
+  #elif defined (__clang__) || defined (__GNUC__)
+  return __builtin_bswap32 (n);
+  #else
   return (n & 0xff000000) >> 24
        | (n & 0x00ff0000) >>  8
        | (n & 0x0000ff00) <<  8
        | (n & 0x000000ff) << 24;
+  #endif
 }
 
 u64 byte_swap_64 (const u64 n)
 {
+  #if defined (_MSC_VER)
+  return _byteswap_uint64 (n);
+  #elif defined (__clang__) || defined (__GNUC__)
+  return __builtin_bswap64 (n);
+  #else
   return (n & 0xff00000000000000ULL) >> 56
        | (n & 0x00ff000000000000ULL) >> 40
        | (n & 0x0000ff0000000000ULL) >> 24
@@ -45,4 +72,5 @@ u64 byte_swap_64 (const u64 n)
        | (n & 0x0000000000ff0000ULL) << 24
        | (n & 0x000000000000ff00ULL) << 40
        | (n & 0x00000000000000ffULL) << 56;
+  #endif
 }