src/gallium/include/pipe/p_refcnt.h

   1 /**************************************************************************
   2  *
   3  * Copyright 2009 VMware, Inc.
   4  * All Rights Reserved.
   5  *
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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
  34
  35 #ifdef __cplusplus
  36 extern "C" {
  37 #endif
  38
  39
  40 struct pipe_reference
  41 {
  42    unsigned count;
  43 };
  44
  45
  46 static INLINE void
  47 pipe_reference_init(struct pipe_reference *reference, unsigned count)
  48 {
  49    reference->count = count;
  50 }
  51
  52
  53 /**
  54  * Set 'ptr' to point to 'reference' and update reference counting.
  55  * The old thing pointed to, if any, will be unreferenced first.
  56  * 'reference' may be NULL.
  57  *
  58  * XXX: thread safety issues!
  59  */
  60 static INLINE bool
  61 pipe_reference(struct pipe_reference **ptr, struct pipe_reference *reference)
  62 {
  63    bool destroy = FALSE;
  64
  65    /* bump the reference.count first */
  66    if (reference) {
  67       assert(reference->count);
  68       reference->count++;
  69    }
  70
  71    if (*ptr) {
  72       assert((*ptr)->count);
  73       if (--(*ptr)->count == 0) {
  74          destroy = TRUE;
  75       }
  76    }
  77
  78    *ptr = reference;
  79
  80    return destroy;
  81 }
  82
  83
  84 #endif /* P_REFCNT_H */