src/gallium/include/pipe/p_refcnt.h

   1 /**************************************************************************
   2  *
   3  * Copyright 2009 VMware, Inc.
   4  * All Rights Reserved.
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  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
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  14  * The above copyright notice and this permission notice (including the
  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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  26  **************************************************************************/
  27
  28 #ifndef P_REFCNT_H
  29 #define P_REFCNT_H
  30
  31
  32 #include "p_defines.h"
  33 #include "p_atomic.h"
  34
  35
  36 #ifdef __cplusplus
  37 extern "C" {
  38 #endif
  39
  40
  41 struct pipe_reference
  42 {
  43    struct pipe_atomic count;
  44 };
  45
  46
  47 static INLINE void
  48 pipe_reference_init(struct pipe_reference *reference, unsigned count)
  49 {
  50    p_atomic_set(&reference->count, count);
  51 }
  52
  53
  54 static INLINE boolean
  55 pipe_is_referenced(struct pipe_reference *reference)
  56 {
  57    return p_atomic_read(&reference->count) != 0;
  58 }
  59
  60
  61 /**
  62  * Update reference counting.
  63  * The old thing pointed to, if any, will be unreferenced.
  64  * Both 'ptr' and 'reference' may be NULL.
  65  * \return TRUE if the object's refcount hits zero and should be destroyed.
  66  */
  67 static INLINE boolean
  68 pipe_reference(struct pipe_reference *ptr, struct pipe_reference *reference)
  69 {
  70    boolean destroy = FALSE;
  71
  72    if(ptr != reference) {
  73       /* bump the reference.count first */
  74       if (reference) {
  75          assert(pipe_is_referenced(reference));
  76          p_atomic_inc(&reference->count);
  77       }
  78
  79       if (ptr) {
  80          assert(pipe_is_referenced(ptr));
  81          if (p_atomic_dec_zero(&ptr->count)) {
  82             destroy = TRUE;
  83          }
  84       }
  85    }
  86
  87    return destroy;
  88 }
  89
  90
  91 #ifdef __cplusplus
  92 }
  93 #endif
  94
  95 #endif /* P_REFCNT_H */