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runtime/platform/utils_fuchsia.h

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef PLATFORM_UTILS_FUCHSIA_H_
 #define PLATFORM_UTILS_FUCHSIA_H_
 
 #include "platform/assert.h"
 
 namespace dart {
 
 inline int Utils::CountLeadingZeros(uword x) {
-  UNIMPLEMENTED();
-  return 0;
+#if defined(ARCH_IS_32_BIT)
+  return __builtin_clzl(x);
+#elif defined(ARCH_IS_64_BIT)
+  return __builtin_clzll(x);
+#else
+#error Architecture is not 32-bit or 64-bit.
+#endif
 }
 
 
 inline int Utils::CountTrailingZeros(uword x) {
-  UNIMPLEMENTED();
-  return 0;
+#if defined(ARCH_IS_32_BIT)
+  return __builtin_ctzl(x);
+#elif defined(ARCH_IS_64_BIT)
+  return __builtin_ctzll(x);
+#else
+#error Architecture is not 32-bit or 64-bit.
+#endif
 }
 
 
 inline uint16_t Utils::HostToBigEndian16(uint16_t value) {
   UNIMPLEMENTED();
   return 0;
 }
 
 
 inline uint32_t Utils::HostToBigEndian32(uint32_t value) {
@@ skipping 27 matching lines @@
 
 
 inline char* Utils::StrError(int err, char* buffer, size_t bufsize) {
   UNIMPLEMENTED();
   return NULL;
 }
 
 }  // namespace dart
 
 #endif  // PLATFORM_UTILS_FUCHSIA_H_