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Ring buffer example

 
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treitmey



Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA

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Ring buffer example
PostPosted: Thu Aug 12, 2004 8:46 am     Reply with quote

Ring buffer example
circular buffer
Code:

#define TXSIZE   64 //ie:buffer is 2^6=64 bytes deep
#define TXMASK TXSIZE-1
int8 TX_BUF[TXSIZE];
//==========tx_buffer===================//
//For transmitting data via USART and using interrupts
//must have #INT_TBE defined
void tx_buffer(char *data,int8 size)
{
  int8 x;
  for (x=0;x<size;x++,data++)
  {
    //chksum=chksum+*data;
    TX_BUF[tx_indx_i] = *data;
    tx_indx_i++; //when filling the buffer, increment the index
    tx_indx_i &= TXMASK;//mask off the index,.. this makes it circular
    if(tx_indx_o==tx_indx_i)  //if the indexs match we are full
    {
      bit_set(ERRORS,1);//set error flag bit 1 for tx overflow
      disable_interrupts(INT_TBE);
      tx_indx_o++;
      tx_indx_o &= TXMASK;
    }
  }
  RS485TX();//enable transmit
  delay_ms(2);//2ms is as fast as it can go,... error on 1ms delay
  enable_interrupts(INT_TBE);
  return;
}
//============ Empty buffer================//
//=======================TXisr============================//
//Takes data from buffer and puts it into a TX stream (RS485)
//uses interrupts to empty buffer at proper rate
#INT_TBE
void TXisr(void)
{
  CREN = 0;
  fputc(TX_BUF[tx_indx_o],RS485);//empty  the buffer of a byte
  tx_indx_o++;//increment the index
  tx_indx_o &= TXMASK;//mask off the index,.. this makes it circular
  if(tx_indx_o==tx_indx_i)//if they are == buffer is empty, turn off int_tbe
  {
    disable_interrupts(INT_TBE);
    CREN = 1;
  }
  set_timer1(TIMER1_INIT);//reset the timer
  //enable_interrupts(INT_RB);// don't have the keypad INT bother the RX INT
}

zspikes



Joined: 10 Jan 2013
Posts: 7

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PostPosted: Thu Jan 10, 2013 7:39 am     Reply with quote

Thank you!!! Very Happy
very useful!
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