pd.if.org Git - liblfds/blob - liblfds/liblfds7.1.0/liblfds710/src/lfds710_stack/lfds710_stack_pop.c

   1 /***** includes *****/
   2 #include "lfds710_stack_internal.h"
   3
   4
   5
   6
   7
   8 /****************************************************************************/
   9 int lfds710_stack_pop( struct lfds710_stack_state *ss,
  10                        struct lfds710_stack_element **se )
  11 {
  12   char unsigned
  13     result;
  14
  15   lfds710_pal_uint_t
  16     backoff_iteration = LFDS710_BACKOFF_INITIAL_VALUE;
  17
  18   struct lfds710_stack_element LFDS710_PAL_ALIGN(LFDS710_PAL_ALIGN_DOUBLE_POINTER)
  19     *new_top[PAC_SIZE],
  20     *volatile original_top[PAC_SIZE];
  21
  22   LFDS710_PAL_ASSERT( ss != NULL );
  23   LFDS710_PAL_ASSERT( se != NULL );
  24
  25   LFDS710_MISC_BARRIER_LOAD;
  26
  27   original_top[COUNTER] = ss->top[COUNTER];
  28   original_top[POINTER] = ss->top[POINTER];
  29
  30   do
  31   {
  32     if( original_top[POINTER] == NULL )
  33     {
  34       *se = NULL;
  35       return 0;
  36     }
  37
  38     new_top[COUNTER] = original_top[COUNTER] + 1;
  39     new_top[POINTER] = original_top[POINTER]->next;
  40
  41     LFDS710_PAL_ATOMIC_DWCAS( ss->top, original_top, new_top, LFDS710_MISC_CAS_STRENGTH_WEAK, result );
  42
  43     if( result == 0 )
  44     {
  45       LFDS710_BACKOFF_EXPONENTIAL_BACKOFF( ss->pop_backoff, backoff_iteration );
  46       LFDS710_MISC_BARRIER_LOAD;
  47     }
  48   }
  49   while( result == 0 );
  50
  51   *se = original_top[POINTER];
  52
  53   LFDS710_BACKOFF_AUTOTUNE( ss->pop_backoff, backoff_iteration );
  54
  55   return 1;
  56 }
  57