queue.c

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/*
 * See Licensing and Copyright notice in naev.h
 */

#include <stdlib.h>
 
#include "queue.h"
 
#include "log.h"

typedef struct Node_ *Node;
typedef struct Node_ {
   void *data; 
   Node  next; 
} Node_;

typedef struct Queue_ {
   Node first; 
   Node last;  
} Queue_;

Queue q_create( void )
{
   /* Create the queue. */
   Queue q = malloc( sizeof( Queue_ ) );
 
   /* Check that we didn't get a NULL. */
#ifdef DEBUGGING
   if ( q == NULL ) {
      WARN( "q == NULL" );
      return NULL;
   }
#endif /* DEBUGGING */
 
   /* Assign nothing into it. */
   q->first = NULL;
   q->last  = NULL;
 
   /* And return (a pointer to) the newly created queue. */
   return q;
}

void q_destroy( Queue q )
{
#ifdef DEBUGGING
   /* Check that we didn't get a NULL. */
   if ( q == NULL ) {
      WARN( "q == NULL" );
      return;
   }
#endif /* DEBUGGING */
 
   /* Free all the data. */
   while ( q->first != NULL )
      q_dequeue( q );
 
   free( q );
 
   return;
}

void q_enqueue( Queue q, void *data )
{
   Node n;
 
#ifdef DEBUGGING
   /* Check that we didn't get a NULL. */
   if ( q == NULL ) {
      WARN( "q == NULL" );
      return;
   }
#endif /* DEBUGGING */
 
   /* Create a new node. */
   n       = malloc( sizeof( Node_ ) );
   n->data = data;
   n->next = NULL;
   if ( q->first == NULL )
      q->first = n;
   else
      q->last->next = n;
   q->last = n;
 
   return;
}

void *q_dequeue( Queue q )
{
   void *d;
   Node  temp;
 
#ifdef DEBUGGING
   /* Check that we didn't get a NULL. */
   if ( q == NULL ) {
      WARN( "q == NULL" );
      return NULL;
   }
#endif /* DEBUGGING */
 
   /* Check that it's not empty. */
   if ( q->first == NULL )
      return NULL;
 
   d        = q->first->data;
   temp     = q->first;
   q->first = q->first->next;
   if ( q->first == NULL )
      q->last = NULL;
   free( temp );
 
   return d;
}

int q_isEmpty( Queue q )
{
#ifdef DEBUGGING
   /* Check that we didn't get a NULL. */
   if ( q == NULL ) {
      WARN( "q == NULL" );
      return -1;
   }
#endif /* DEBUGGING */
 
   if ( q->first == NULL )
      return 1;
   else
      return 0;
}