key_buf_queue.c

UART FOR uCOS and Capsensor Test

/**
* usdk130
* queue for key message buffer
* by liwei, 2006,09
*algorithm referenced from 
*
* C: The Complete Reference, 4th Ed. (Paperback)
* by Herbert Schildt
*/

#include "key_buf_queue.h"
#include "string.h"


//#define KEY_DEBUG
#ifdef KEY_DEBUG
#define keydbg(x...)   printf("KEY debug : " x)
#else
#define keydbg(...)     do { } while (0)
#endif




INT32U key_value[KEY_MESSAGE_BUF_SIZE]={0};
unsigned int spos = 0;
unsigned int rpos = 0;
unsigned int cnt = 0;

/* Store ints in the queue. */
void qstore( INT32U q )
{

#if 0
  if( is_full() ) {
//	    printf("List Full\n");
   	 return;
  }
#endif

  key_value[spos] = q;
  spos++;
  if( spos==KEY_MESSAGE_BUF_SIZE ) 
  	spos = 0; /* loop back */
  cnt++;

	keydbg("qstore key_value[%d] = %x\t, cnt =%d\n", spos, q, cnt);

}

/* Retrieve an element. */
INT32U qretrieve(void)
{
  int value;
  
  if( is_empty() ) {
//    printf("List empty()\n");
    return 0;
  }
  value =  key_value[rpos];
  rpos++;
  if(rpos == KEY_MESSAGE_BUF_SIZE)  
  	rpos = 0; /* loop back */  
  cnt--;
  
	keydbg("qretrieve value = %x, rpos = %d\t, cnt =%d\n",value, rpos, cnt);
  return value;
}


int is_empty()
{
	if ( cnt == 0 ) {
		return 1;
	}

	return 0;
}


int is_full()
{
	if (cnt == KEY_MESSAGE_BUF_SIZE ) {
		return 1;		
	}
	return 0;
}

INT32U sizeof_key_buf()
{
	return cnt;
}