queue.c

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

static queue* kdqueue = NULL;

void qbuild
(
   void
)
{
   kdqueue = (queue*)malloc(sizeof(queue));
   kdqueue->first = NULL;
   kdqueue->last = NULL;
   
   return;
}

void qinsert
(
   qnode*   new
)
{
   new->next = NULL;
   if( kdqueue->first == NULL )
   {
      kdqueue->first = new;
      kdqueue->last = new;
   }
   else
   {
      kdqueue->last->next = new;
      kdqueue->last = new;
   }
   
   return;
}

qnode* qretrieve
(
   void
)
{
   return kdqueue->first;
}

void qdelete
(
   void
)
{
   qnode*   p  =  NULL  ; // auxiliary pointer
   
   if( kdqueue->first->next == NULL )
   {
      free(kdqueue->first->info);
      free(kdqueue->first);
      kdqueue->first = NULL;
      kdqueue->last = NULL;
   }
   else
   {
      p = kdqueue->first;
      kdqueue->first = p->next;
      free(p->info);
      free(p);
   }
   
   return;
}

int qempty
(
   void
)
{
   return kdqueue->first == NULL;
}

void qdestroy
(
   void
)
{
   qnode*   p  =  NULL  ;
   qnode*   q  =  NULL  ;
   
   p = kdqueue->first;
   while( p )
   {
      q = p;
      p = p->next;
      free(q->info);
      free(q);
   }
   free(kdqueue);
   kdqueue = NULL;
   
   return;
}