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      1 /*
      2  * Copyright (C) 2010 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 ANDROID_CUTILS_ATOMIC_X86_H
     18 #define ANDROID_CUTILS_ATOMIC_X86_H
     19 
     20 #include <stdint.h>
     21 
     22 #ifndef ANDROID_ATOMIC_INLINE
     23 #define ANDROID_ATOMIC_INLINE inline __attribute__((always_inline))
     24 #endif
     25 
     26 extern ANDROID_ATOMIC_INLINE void android_compiler_barrier(void)
     27 {
     28     __asm__ __volatile__ ("" : : : "memory");
     29 }
     30 
     31 #if ANDROID_SMP == 0
     32 extern ANDROID_ATOMIC_INLINE void android_memory_barrier(void)
     33 {
     34     android_compiler_barrier();
     35 }
     36 #else
     37 extern ANDROID_ATOMIC_INLINE void android_memory_barrier(void)
     38 {
     39     __asm__ __volatile__ ("mfence" : : : "memory");
     40 }
     41 #endif
     42 
     43 extern ANDROID_ATOMIC_INLINE int32_t
     44 android_atomic_acquire_load(volatile const int32_t *ptr)
     45 {
     46     int32_t value = *ptr;
     47     android_compiler_barrier();
     48     return value;
     49 }
     50 
     51 extern ANDROID_ATOMIC_INLINE int32_t
     52 android_atomic_release_load(volatile const int32_t *ptr)
     53 {
     54     android_memory_barrier();
     55     return *ptr;
     56 }
     57 
     58 extern ANDROID_ATOMIC_INLINE void
     59 android_atomic_acquire_store(int32_t value, volatile int32_t *ptr)
     60 {
     61     *ptr = value;
     62     android_memory_barrier();
     63 }
     64 
     65 extern ANDROID_ATOMIC_INLINE void
     66 android_atomic_release_store(int32_t value, volatile int32_t *ptr)
     67 {
     68     android_compiler_barrier();
     69     *ptr = value;
     70 }
     71 
     72 extern ANDROID_ATOMIC_INLINE int
     73 android_atomic_cas(int32_t old_value, int32_t new_value, volatile int32_t *ptr)
     74 {
     75     int32_t prev;
     76     __asm__ __volatile__ ("lock; cmpxchgl %1, %2"
     77                           : "=a" (prev)
     78                           : "q" (new_value), "m" (*ptr), "0" (old_value)
     79                           : "memory");
     80     return prev != old_value;
     81 }
     82 
     83 extern ANDROID_ATOMIC_INLINE int
     84 android_atomic_acquire_cas(int32_t old_value,
     85                            int32_t new_value,
     86                            volatile int32_t *ptr)
     87 {
     88     /* Loads are not reordered with other loads. */
     89     return android_atomic_cas(old_value, new_value, ptr);
     90 }
     91 
     92 extern ANDROID_ATOMIC_INLINE int
     93 android_atomic_release_cas(int32_t old_value,
     94                            int32_t new_value,
     95                            volatile int32_t *ptr)
     96 {
     97     /* Stores are not reordered with other stores. */
     98     return android_atomic_cas(old_value, new_value, ptr);
     99 }
    100 
    101 extern ANDROID_ATOMIC_INLINE int32_t
    102 android_atomic_add(int32_t increment, volatile int32_t *ptr)
    103 {
    104     __asm__ __volatile__ ("lock; xaddl %0, %1"
    105                           : "+r" (increment), "+m" (*ptr)
    106                           : : "memory");
    107     /* increment now holds the old value of *ptr */
    108     return increment;
    109 }
    110 
    111 extern ANDROID_ATOMIC_INLINE int32_t
    112 android_atomic_inc(volatile int32_t *addr)
    113 {
    114     return android_atomic_add(1, addr);
    115 }
    116 
    117 extern ANDROID_ATOMIC_INLINE int32_t
    118 android_atomic_dec(volatile int32_t *addr)
    119 {
    120     return android_atomic_add(-1, addr);
    121 }
    122 
    123 extern ANDROID_ATOMIC_INLINE int32_t
    124 android_atomic_and(int32_t value, volatile int32_t *ptr)
    125 {
    126     int32_t prev, status;
    127     do {
    128         prev = *ptr;
    129         status = android_atomic_cas(prev, prev & value, ptr);
    130     } while (__builtin_expect(status != 0, 0));
    131     return prev;
    132 }
    133 
    134 extern ANDROID_ATOMIC_INLINE int32_t
    135 android_atomic_or(int32_t value, volatile int32_t *ptr)
    136 {
    137     int32_t prev, status;
    138     do {
    139         prev = *ptr;
    140         status = android_atomic_cas(prev, prev | value, ptr);
    141     } while (__builtin_expect(status != 0, 0));
    142     return prev;
    143 }
    144 
    145 #endif /* ANDROID_CUTILS_ATOMIC_X86_H */
    146