QUEUE.C

#include <windows.h> 
#include "queue.h" 
 
qnode *addtoq(queue *q, void *p) { 
qnode *t; 
 
t = (qnode *) LocalAlloc(0, sizeof(qnode)); 
if (t == NULL) return NULL; 
t->ptr = p; 
t->next = NULL; 
if (q->head == NULL) { 
t->prev = NULL; 
q->head = t; 
q->tail = t; 
} else { 
t->prev = q->tail; 
q->tail->next = t; 
q->tail = t; 
} 
 
return t; 
} 
 
void *removeheadfromq(queue *q) { 
qnode *t; 
void *p; 
 
if (q->head == NULL) return NULL; 
 
t = q->head; 
q->head = t->next; 
if (q->head == NULL) q->tail = NULL; 
else q->head->prev = NULL; 
p = t->ptr; 
LocalFree(t); 
 
return p; 
} 
 
void *removeqnodefromq(queue *q, qnode *t) { 
void *p; 
 
if (q->head == t) q->head = t->next; 
if (q->tail == t) q->tail = t->prev; 
if (t->next != NULL) t->next->prev = t->prev; 
if (t->prev != NULL) t->prev->next = t->next; 
p = t->ptr; 
LocalFree(t); 
 
return p; 
} 
 
queue *newq(void) { 
queue *q; 
 
q = (queue *) LocalAlloc(0, sizeof(queue)); 
if (q == NULL) return NULL; 
q->head = NULL; 
q->tail = NULL; 
 
return q; 
}