ring Documentation

Description

This ring buffer can contain elements of any size. Multiple ring buffers can be used in the same project. This ring buffer uses a struct with information about the ring buffer. The compleet ring buffer is descripted in this header file. There is no accompanying c file. All functions are static inline functions.

For ring buffers containing char's some extra functionality is added. E.g. a function ringGetLine() to read a line (text ending with a \n) from the ring buffer.

Examples

A small example how to use this ringbuffer in an application is:

    #include <stdio.h>
    #include "ring.h"
    
    #define BUFFERSIZE  100
    
    int main(void)
    {
      int square, data, count;
      
      // Create the ring buffer with BUFFERSIZE elements of integers
      ring_t *pRing = ringCreate(sizeof(int), BUFFERSIZE);
      
      // Fill the ring buffer with 16 elements
      for (int i=0; i<16; i++) {
        square = i * i;
        ringWrite(pRing, (uint8_t *) (&square));
      } 
      count = ringGetCount(pRing);
      printf("The buffer is filled with %d elements\n", count);
      
      // Read 10 elements from the ring buffer
      for(int i=0; i<10; i++) {
        ringRead(pRing, (uint8_t *) (&data));
        printf("read from buffer: %d\n", data);
      }
      count = ringGetCount(pRing);
      printf("The buffer is now filled with %d elements\n", count);
      
      // Read all elements from the ring buffer until it is empty
      while( ! ringIsEmpty(pRing) ) {
        ringRead(pRing, (uint8_t *) (&data));
        printf("read from buffer: %d\n", data);
      }
      count = ringGetCount(pRing);
      printf("The buffer is now filled with %d elements\n", count);
     
      return 0;
    }

An incomplete example with two ring buffers:

#define COMMBUFFERSIZE   4096
#define RXBUFFERSIZE     4096
#define PXLBUFFERSIZE    4096
#define LINEBUFFERSIZE   256

typedef struct pixel_struct {
  uint8_t r;
  uint8_t g;
  uint8_t b;
} pxl_t; 

char lineBuffer[LINEBUFFERSIZE];  // buffer for a complete packet
char commBuffer[COMMBUFFERSIZE];  // buffer for serial communication

int main(void)
{
  unsigned int r, g, b;
  pxl_t        wpixel;
  pxl_t        rpixel;
  ring_t *pRingRx  = ringCreate(sizeof(char), RXBUFFERSIZE);
  ring_t *pRingPxl = ringCreate(sizeof(pxl_t), PXLBUFFERSIZE);
  
  // initialize serial communication 
  
  while(1) {
    // some code receive serial communication 
  
    // copy received chars to Rx ring buffer
    for(int i=0; i<len; i++) {   // len is number of receivedd characters
      ringWrite(pRingRx, &commBuffer[i]);
    }
    
    // copy pixel packets from Rx ring buffer to Pxl ring buffer
    while (ringGetLine(pRingRx, (uint8_t *) lineBuffer) ) {
      sscanf(lineBuffer, "%u;%u;%u", &r, &g, &b);
      wpixel.r = r/8;
      wpixel.g = g/8;
      wpixel.b = b/8;
      ringWrite(pRingPxl, (uint8_t *) (&wpixel));
    }
    
   // read and print pixel packets from Pxl ring buffer
    if (! ringIsEmpty(pRingPxl) ) {
      ringRead(pRingPxl, (uint8_t *) (&rpixel));
      printf("(%u %u %u)\n", rpixel.r, rpixel.g, rpixel.b);
    }
  }
  
  return 0;
}

Contact

Author

Wim Dolman (w.e.dolman@hva.nl)

Version

1.1
Latest version can be found here: http://dolman-wim.nl/xmega/libraries/index.php

Date

27-05-2021

License

This library is free software. You can redistribute it and/or modify it. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY.