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      1 /*
      2  * Copyright (C) 2014 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef ART_RUNTIME_ARCH_MEMCMP16_H_
     18 #define ART_RUNTIME_ARCH_MEMCMP16_H_
     19 
     20 #include <cstddef>
     21 #include <cstdint>
     22 
     23 // memcmp16 support.
     24 //
     25 // This can either be optimized assembly code, in which case we expect a function __memcmp16,
     26 // or generic C support.
     27 //
     28 // In case of the generic support we declare two versions: one in this header file meant to be
     29 // inlined, and a static version that assembly stubs can link against.
     30 //
     31 // In both cases, MemCmp16 is declared.
     32 
     33 #if defined(__aarch64__) || defined(__arm__) || defined(__mips) || defined(__i386__) || defined(__x86_64__)
     34 
     35 extern "C" uint32_t __memcmp16(const uint16_t* s0, const uint16_t* s1, size_t count);
     36 #define MemCmp16 __memcmp16
     37 
     38 #else
     39 
     40 // This is the generic inlined version.
     41 static inline int32_t MemCmp16(const uint16_t* s0, const uint16_t* s1, size_t count) {
     42   for (size_t i = 0; i < count; i++) {
     43     if (s0[i] != s1[i]) {
     44       return static_cast<int32_t>(s0[i]) - static_cast<int32_t>(s1[i]);
     45     }
     46   }
     47   return 0;
     48 }
     49 
     50 extern "C" int32_t memcmp16_generic_static(const uint16_t* s0, const uint16_t* s1, size_t count);
     51 #endif
     52 
     53 namespace art {
     54 
     55 namespace testing {
     56 
     57 // A version that is exposed and relatively "close to the metal," so that memcmp16_test can do
     58 // some reasonable testing. Without this, as __memcmp16 is hidden, the test cannot access the
     59 // implementation.
     60 int32_t MemCmp16Testing(const uint16_t* s0, const uint16_t* s1, size_t count);
     61 
     62 }
     63 
     64 }  // namespace art
     65 
     66 #endif  // ART_RUNTIME_ARCH_MEMCMP16_H_
     67