Lpc2000

Charles,

Do you find this version to be "thread safe" when a UART ISR is filling
it and the main program is processing (i.e. emptying) it?

Curt

-----Original Message-----
From: embeddedjanitor [mailto:charles.manning@...] 
Sent: Thursday, March 04, 2004 11:49 AM
To: lpc2000@yahoogroups.com
Subject: [lpc2000] Re: Circular buffers


--- In lpc2000@yahoogroups.com, "Curt Powell" <curt.powell@s...> 
wrote:
> Can someone point me to some circular buffer routines?
There are various ways to implement circular buffers. The easiest 
way, and most robust way, IMHO is to use a counter to track how many 
items are in the list rather than comparing head and tail.

example
typedef struct{
  U8 fifo[uart_FIFO_SIZE];
  U32 head;
  U32 tail;
  U32 holding;
} uart_Buffer;
      // put a byte into the list
      if(s->rx.holding >= uart_FIFO_SIZE)
      {
        //Full, so got to throw away the oldest byte
        s->rx.holding = uart_FIFO_SIZE - 1;
        s->rx.tail++;
        if(s->rx.tail >= uart_FIFO_SIZE)
        {
          s->rx.tail = 0;
        }
      }
      s->rx.fifo[s->rx.head] = b;
      s->rx.head++;
      if(s->rx.head >= uart_FIFO_SIZE)
      {
        s->rx.head = 0;
      }
      s->rx.holding++;


  // pull a byte out of the list
  if(s->rx.holding > 0)
  {
    *pData = s->rx.fifo[s->rx.tail];
    s->rx.tail++;
    if(s->rx.tail  >= uart_FIFO_SIZE)
    {
      s->rx.tail = 0;
    }
    s->rx.holding--;
    retval = 1;
  }

  // initialise
  s->rx.tail = s->rx.head = s->rx.holding = 0;





 
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