FIFO example

gistfile1.txt

/*
 *   Jeonghun Lee 
 *   Recently,  I made FIFO functions by using Array in MSP430 for optimization  
 */


#define MAX_TX_BUFF		1024
#define MAX_RX_BUFF		128

/*
 *   TX-FIFO , Array Type FIFO so only used txhead and txcnt
 */
char txmsg[MAX_TX_BUFF]={0};	 //FIFO Buffer
uint16_t  txhead=0;	             //FIFO first Postion
uint16_t  txcnt=0;	             //FIFO Size


/*
 *   RX-FIFO , Arrary Type FIFO so only used rxtail and rxcnt
 */
char  rxmsg[MAX_RX_BUFF]={0};		//FIFO Buffer
uint16_t  rxtail=0;	             	//FIFO RX Last Postion but Real Last Postion (rxtail-1).
uint16_t  rxcnt=0;	            	//FIFO RX Count  (rxcnt)


uint16_t rdUART1DATA(char *data , uint16_t lens) // remove elements from rxmsg
{
	uint16_t i,start,end,cnt=0;

	if(rxcnt >= (MAX_RX_BUFF-1))  					{ rxtail=0; rxcnt=0; return 1;}	// overun
	else if(rxcnt <= 0 )							      {  return 2;} //  empty buffer 
	else if(rxcnt < lens  )							    {  return 3;} //  underrun 

/*
 *   start point 
 */ 
	if( rxcnt > rxtail )	start = MAX_RX_BUFF-(rxcnt-rxtail); // rxcnt > rxtail means 
	else					        start = rxtail-rxcnt;               // 

	end = lens;

	cnt = 0;
	i= start;

	while( cnt < end ) //find sync
	{
		data[i] = rxmsg[i];
		cnt++;													// sync position
		i=((i+1) & (MAX_RX_BUFF-1));
	}

	return 0;
}

uint16_t rdUART1STR(char *data, uint16_t lens)
{

	uint16_t rt=0;

	rt = rdUART1DATA(data,lens);

	if(rt != 0){
		rxcnt=0;
		rxtail=0;
	}
  
	return rt;

}

bspIState_t intState;

uint16_t wrUART1DATA(char *data , uint16_t lens)
{
	uint16_t i=0,pos=0;
	if((txcnt+lens) > (MAX_TX_BUFF-1)) 	return 1;

	for(i=0;i<lens;i++)
	{
		BSP_ENTER_CRITICAL_SECTION(intState);
			pos = (txhead + txcnt) & (MAX_TX_BUFF-1);
			txmsg[pos] = *(data+i);
			txcnt++;
		BSP_EXIT_CRITICAL_SECTION(intState);
	}

	if(!(UCA1IFG&UCTXIFG))
		UCA1IFG |= UCTXIFG;


	return 0;
}



uint16_t wrUART1STR(char *data, uint16_t lens)
{

	uint16_t rt=0;

	rt = wrUART1DATA(data,lens);

	if(rt != 0){
		BSP_ENTER_CRITICAL_SECTION(intState);
		txcnt=0;		
	  BSP_EXIT_CRITICAL_SECTION(intState);
	}

	return 0;
}


#if defined(__TI_COMPILER_VERSION__) 
#pragma vector=USCI_A1_VECTOR
__interrupt void USCI_A1_ISR(void)
#else
#error Compiler not supported!
#endif

{
    if(UCA1IFG & UCRXIFG){
    	UCA1IFG &= ~UCRXIFG;
      
      //FIFO,  Input 
	    rxmsg[rxtail] = UCA1RXBUF; // insert data from register 
	    rxtail = (rxtail + 1) & (MAX_RX_BUFF-1); // loop routine 
	    rxcnt++;
      
    }


    if(UCA1IFG & UCTXIFG){ //somtimes, have the problem so change to polling mode
    	UCA1IFG &= ~UCTXIFG;
    	if(txcnt > 0 ){
    		UCA1TXBUF = txmsg[txhead];
    		txhead = (txhead + 1) & (MAX_TX_BUFF-1);
    		txcnt--;
    	}
    }
}