lib/libddekit/src/semaphore.c

   1 #include "common.h"
   2 #include <ddekit/condvar.h>
   3 #include <ddekit/lock.h>
   4 #include <ddekit/memory.h>
   5 #include <ddekit/panic.h>
   6 #include <ddekit/semaphore.h>
   7
   8 #ifdef DDEBUG_LEVEL_SEMAPHORE
   9 #undef DDEBUG
  10 #define DDEBUG DDEBUG_LEVEL_SEMAPHORE
  11 #endif
  12
  13 #include "debug.h"
  14 #include "thread.h"
  15
  16 struct ddekit_sem {
  17         unsigned count;
  18         ddekit_thread_t *wait_queue;
  19 };
  20
  21 #define SEM_DEBUG(p)                                                  \
  22     do {                                                              \
  23                 DDEBUG_MSG_VERBOSE("%s, %p, %d\n",__func__, sem, sem->count); \
  24         } while(0)
  25
  26 /*****************************************************************************
  27  *     ddekit_sem_init                                                       *
  28  *************************+**************************************************/
  29 ddekit_sem_t *ddekit_sem_init(int value)
  30 {
  31         ddekit_sem_t *sem;
  32
  33         sem = (ddekit_sem_t *) ddekit_simple_malloc(sizeof(ddekit_sem_t));
  34
  35         sem->count = value;
  36         sem->wait_queue = NULL;
  37
  38         SEM_DEBUG(p);
  39         return sem;
  40 }
  41
  42 /*****************************************************************************
  43  *     ddekit_sem_deinit                                                     *
  44  ****************************************************************************/
  45 void ddekit_sem_deinit(ddekit_sem_t *sem)
  46 {
  47         SEM_DEBUG(p);
  48         ddekit_simple_free(sem);
  49 }
  50
  51 /*****************************************************************************
  52  *     ddekit_sem_down                                                       *
  53  ****************************************************************************/
  54 void ddekit_sem_down(ddekit_sem_t *sem)
  55 {
  56         SEM_DEBUG(p);
  57         if(sem->count == 0) {
  58                 if(sem->wait_queue == NULL) {
  59                         sem->wait_queue = ddekit_thread_myself();
  60                 } else {
  61                         ddekit_thread_t *pos = sem->wait_queue;
  62                         while(pos->next != NULL) {
  63                                 pos = pos->next;
  64                         }
  65                         pos->next = ddekit_thread_myself();
  66                 }
  67                 _ddekit_thread_schedule();
  68         } else {
  69                 sem->count--;
  70         }
  71 }
  72
  73 /*****************************************************************************
  74  *     ddekit_sem_down_try                                                   *
  75  ****************************************************************************/
  76 int ddekit_sem_down_try(ddekit_sem_t *sem)
  77 {
  78         if(sem->count == 0) {
  79                 return -1;
  80         }
  81         sem->count--;
  82         return 0;
  83 }
  84
  85 /*****************************************************************************
  86  *     ddekit_sem_up                                                         *
  87  ****************************************************************************/
  88 void ddekit_sem_up(ddekit_sem_t *sem)
  89 {
  90         SEM_DEBUG(p);
  91         if (sem->wait_queue == NULL) {
  92                 sem->count++;
  93                 return;
  94         } else {
  95                 ddekit_thread_t *waiter = sem->wait_queue;
  96                 sem->wait_queue = waiter->next;
  97                 waiter->next = NULL;
  98                 _ddekit_thread_enqueue(waiter);
  99                 ddekit_thread_schedule();
 100         }
 101 }
 102
 103 /****************************************************************************
 104  *     ddekit_sem_down_timed                                                *
 105  ***************************************************************************/
 106 int ddekit_sem_down_timed(ddekit_sem_t *sem, int timo )
 107 {
 108         ddekit_panic("not implemented!");
 109         return 0;
 110 }
 111