Path: chuka.playstation.co.uk!scea!peter_alau@playstation.sony.com
From: Elliott Lee <tenchi@shell.jps.net>
Newsgroups: scee.yaroze.programming.2d_graphics
Subject: Re: A simple Queue
Date: Wed, 23 Sep 1998 15:59:35 -0700
Organization: SCEA News Server
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Are you sure that your QUEUE_Init is dereferencing its pointer
properly?  Seems to me that:

	void QUEUE_Init(QUEUE *q)

is the same as

	void QUEUE_Init(QUEUE q[])

which means that

	*q[i] = QUEUE_NULL;

is wrong because "q" is already a pointer and that you should be
writing:

	q[i] = QUEUE_NULL;

Just an initial observation...
- e!

Antony Arciuolo wrote:
> 
> I'm trying to make a Queue, that's all, but when I typedef the type of the
> Queue (implemented as an array) the system freezes. Shorts work fine, chars
> work fine, but I will be using this Queue for long pointers, and it just
> isn't working.
> 
> Here is Queue.h:
> 
> #ifndef QUEUE_H
> #define QUEUE_H
> 
> // INCLUDES -------------------------------------------------
> 
> #include <assert.h>
> #include <stdlib.h>
> 
> // DEFINITIONS ----------------------------------------------
> 
> #define QUEUE_DEBUG    (1)
> #define QUEUE_RUN_MAIN (0)
> 
> #define QUEUE_SIZEOF   (10)
> #define QUEUE_OVERHEAD ( 3)
> #define QUEUE_HEAD     (QUEUE_SIZEOF)
> #define QUEUE_TAIL     (QUEUE_SIZEOF + 1)
> #define QUEUE_COUNTER  (QUEUE_SIZEOF + 2)
> 
> #define QUEUE_NULL (-1)
> 
> typedef long QUEUE_DataType;
> typedef QUEUE_DataType QUEUE[QUEUE_SIZEOF + QUEUE_OVERHEAD];
> 
> // PROTOTYPES -----------------------------------------------
> 
> void QUEUE_Init(QUEUE *q);
> void QUEUE_Push(QUEUE *q, QUEUE_DataType item);
> QUEUE_DataType QUEUE_Read(QUEUE *q);
> QUEUE_DataType QUEUE_Pop(QUEUE *q);
> short QUEUE_IsEmpty(QUEUE *q);
> 
> #if (QUEUE_DEBUG)
> void QTest(void);
> void QUEUE_Dump(QUEUE *q);
> #endif
> 
> Here is Queue.c:
> 
> #include "Queue.h"
> 
> void QUEUE_Init(QUEUE *q)
> {
>  short i;
>  for (i = 0; i < QUEUE_SIZEOF; i++)
>  {
> #if (QUEUE_DEBUG)
>  printf("Init'ing %d to %d\n", i, QUEUE_NULL);
> #endif
>   *q[i] = QUEUE_NULL;
> 
> #if (QUEUE_DEBUG)
>  printf("*q[%d] is %d\n", i, *q[i]);
> #endif
>  }
> 
>  *q[QUEUE_HEAD]    = 0;
>  *q[QUEUE_TAIL]    = 0;
>  *q[QUEUE_COUNTER] = 0;
> }
> 
> void QUEUE_Push(QUEUE *q, QUEUE_DataType item)
> {
>  short tail;
> 
>  tail = (short)(*q[QUEUE_TAIL]);
> 
> #if (QUEUE_DEBUG)
>  printf("QPush(%p, %d): T:%d\n", q, item, tail);
> #endif
> 
>  if (*q[QUEUE_COUNTER] < QUEUE_SIZEOF)
>  {
>   if (*q[QUEUE_COUNTER] != 0)
>    *q[QUEUE_TAIL] = (*q[QUEUE_TAIL] + 1) % QUEUE_SIZEOF;
> 
>   *q[*q[QUEUE_TAIL]] = item;
>   *q[QUEUE_COUNTER]  = *q[QUEUE_COUNTER] + 1;
>  }
> 
>  else printf("QPush Queue Full! (%p) item: %d\n", q, item);
> }
> 
> QUEUE_DataType QUEUE_Read(QUEUE *q)
> {
> #if (QUEUE_DEBUG)
>  printf("QRead(%p): H:%d item: %d\n", q, *q[QUEUE_HEAD],
> *q[*q[QUEUE_HEAD]]);
> #endif
>  return (*q[*q[QUEUE_HEAD]]);
> }
> 
> QUEUE_DataType QUEUE_Pop(QUEUE *q)
> {
>  QUEUE_DataType x;
> 
> #if (QUEUE_DEBUG)
>  printf("QPop(%p): H:%d item: %d\n", q, *q[QUEUE_HEAD], *q[*q[QUEUE_HEAD]]);
> #endif
> 
>  if (*q[QUEUE_COUNTER] > 0)
>  {
>   x = *q[*q[QUEUE_HEAD]];
> 
>   *q[QUEUE_HEAD] = (*q[QUEUE_HEAD] + 1) % QUEUE_SIZEOF;
>   *q[QUEUE_COUNTER] = *q[QUEUE_COUNTER] - 1;
> 
>   return x;
>  }
> 
>  else
>  {
>   printf("QPop Queue Empty! (%p)\n", q);
>   return (QUEUE_NULL);
>  }
> }
> 
> short QUEUE_IsEmpty(QUEUE *q)
> {
>  return (!(*q[QUEUE_COUNTER]));
> }
> 
> #if (QUEUE_DEBUG)
> void QUEUE_Dump(QUEUE *q)
> {
>  short i;
> 
>  printf("Queue %p:\n", q);
> 
>  for (i = 0; i < (QUEUE_SIZEOF + QUEUE_OVERHEAD); i++)
>  {
>   printf("%d: %d, ", i, *(q[i]));
>  }
> 
>  printf("\n\n");
> }
> 
> void QTest(void)
> {
>  QUEUE q;
>  short i;
>  QUEUE_Init(&q);
> 
>  if (QUEUE_IsEmpty(&q)) printf("1. Queue is Empty!\n");
> 
>  for (i = 0; i < QUEUE_SIZEOF; i++)
>   QUEUE_Push(&q, i);
> 
>  if (QUEUE_IsEmpty(&q)) printf("2. Queue is Empty!\n");
> 
>  QUEUE_Push(&q, 12);
> 
>  for (i = 0; i < QUEUE_SIZEOF; i++)
>   printf("Pop item %d: %d\n" , i, QUEUE_Pop(&q));
> 
>  if (QUEUE_IsEmpty(&q)) printf("3. Queue is Empty!\n");
> 
>  QUEUE_Pop(&q);
> 
>  QUEUE_Dump(&q);
> }
> #endif
> 
> #if (QUEUE_RUN_MAIN)
> void main(void)
> {
>  QUEUE q;
>  short i;
>  QUEUE_Init(&q);
> 
>  if (QUEUE_IsEmpty(&q)) printf("1. Queue is Empty!\n");
> 
>  for (i = 0; i < QUEUE_SIZEOF; i++)
>   QUEUE_Push(&q, i);
> 
>  if (QUEUE_IsEmpty(&q)) printf("2. Queue is Empty!\n");
> 
>  QUEUE_Push(&q, 12);
> 
>  for (i = 0; i < QUEUE_SIZEOF; i++)
>   printf("Pop item %d: %d\n" , i, QUEUE_Pop(&q));
> 
>  if (QUEUE_IsEmpty(&q)) printf("3. Queue is Empty!\n");
> 
>  QUEUE_Pop(&q);
> 
>  QUEUE_Dump(&q);
> }
> #endif
> 
> #endif
> 
> Can anyone help? Please! I am testing this in my main by this method:
> 
> void main(void)
> {
>     QTest();
>     return; // I just want to test the Queue
> 
>     ... The rest of my code ...
> 
> }
> 
> - Tony

-- 
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