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1 
2 /*
3  * Copyright 2006 The Android Open Source Project
4  *
5  * Use of this source code is governed by a BSD-style license that can be
6  * found in the LICENSE file.
7  */
8 
9 
10 #ifndef SkThread_platform_DEFINED
11 #define SkThread_platform_DEFINED
12 
13 #if defined(SK_BUILD_FOR_ANDROID)
14 
15 #if defined(SK_BUILD_FOR_ANDROID_NDK)
16 
17 #include <stdint.h>
18 
19 /* Just use the GCC atomic intrinsics. They're supported by the NDK toolchain,
20  * have reasonable performance, and provide full memory barriers
21  */
sk_atomic_inc(int32_t * addr)22 static __attribute__((always_inline)) int32_t sk_atomic_inc(int32_t *addr) {
23     return __sync_fetch_and_add(addr, 1);
24 }
25 
sk_atomic_dec(int32_t * addr)26 static __attribute__((always_inline)) int32_t sk_atomic_dec(int32_t *addr) {
27     return __sync_fetch_and_add(addr, -1);
28 }
29 
30 #else // !SK_BUILD_FOR_ANDROID_NDK
31 
32 /* The platform atomics operations are slightly more efficient than the
33  * GCC built-ins, so use them.
34  */
35 #include <utils/Atomic.h>
36 
37 #define sk_atomic_inc(addr)     android_atomic_inc(addr)
38 #define sk_atomic_dec(addr)     android_atomic_dec(addr)
39 
40 #endif // !SK_BUILD_FOR_ANDROID_NDK
41 
42 #else  // !SK_BUILD_FOR_ANDROID
43 
44 /** Implemented by the porting layer, this function adds 1 to the int specified
45     by the address (in a thread-safe manner), and returns the previous value.
46 */
47 SK_API int32_t sk_atomic_inc(int32_t* addr);
48 /** Implemented by the porting layer, this function subtracts 1 to the int
49     specified by the address (in a thread-safe manner), and returns the previous
50     value.
51 */
52 SK_API int32_t sk_atomic_dec(int32_t* addr);
53 
54 #endif // !SK_BUILD_FOR_ANDROID
55 
56 #ifdef SK_USE_POSIX_THREADS
57 
58 #include <pthread.h>
59 
60 // A SkBaseMutex is a POD structure that can be directly initialized
61 // at declaration time with SK_DECLARE_STATIC/GLOBAL_MUTEX. This avoids the
62 // generation of a static initializer in the final machine code (and
63 // a corresponding static finalizer).
64 //
65 struct SkBaseMutex {
acquireSkBaseMutex66     void    acquire() { pthread_mutex_lock(&fMutex); }
releaseSkBaseMutex67     void    release() { pthread_mutex_unlock(&fMutex); }
68     pthread_mutex_t  fMutex;
69 };
70 
71 // Using POD-style initialization prevents the generation of a static initializer
72 // and keeps the acquire() implementation small and fast.
73 #define SK_DECLARE_STATIC_MUTEX(name)   static SkBaseMutex  name = { PTHREAD_MUTEX_INITIALIZER }
74 
75 // Special case used when the static mutex must be available globally.
76 #define SK_DECLARE_GLOBAL_MUTEX(name)   SkBaseMutex  name = { PTHREAD_MUTEX_INITIALIZER }
77 
78 #define SK_DECLARE_MUTEX_ARRAY(name, count)    SkBaseMutex name[count] = { PTHREAD_MUTEX_INITIALIZER }
79 
80 // A normal mutex that requires to be initialized through normal C++ construction,
81 // i.e. when it's a member of another class, or allocated on the heap.
82 class SkMutex : public SkBaseMutex, SkNoncopyable {
83 public:
84     SkMutex();
85     ~SkMutex();
86 };
87 
88 #else // !SK_USE_POSIX_THREADS
89 
90 // In the generic case, SkBaseMutex and SkMutex are the same thing, and we
91 // can't easily get rid of static initializers.
92 //
93 class SkMutex : SkNoncopyable {
94 public:
95     SkMutex();
96     ~SkMutex();
97 
98     void    acquire();
99     void    release();
100 
101 private:
102     bool fIsGlobal;
103     enum {
104         kStorageIntCount = 64
105     };
106     uint32_t    fStorage[kStorageIntCount];
107 };
108 
109 typedef SkMutex SkBaseMutex;
110 
111 #define SK_DECLARE_STATIC_MUTEX(name)           static SkBaseMutex  name
112 #define SK_DECLARE_GLOBAL_MUTEX(name)           SkBaseMutex  name
113 #define SK_DECLARE_MUTEX_ARRAY(name, count)     SkBaseMutex name[count]
114 
115 #endif // !SK_USE_POSIX_THREADS
116 
117 
118 #endif
119