apps/lib/libmeinos/ringbuf.c

   1 #include <ringbuf.h>
   2 #include <stdlib.h>
   3 #include <sys/types.h>
   4
   5 ringbuf_t *ringbuf_create(size_t size) {
   6   ringbuf_t *ringbuf = malloc(sizeof(ringbuf_t));
   7   ringbuf->buf = malloc(size);
   8   ringbuf->size = size;
   9   ringbuf->wpos = 0;
  10   ringbuf->rpos = 0;
  11   return ringbuf;
  12 }
  13
  14 void ringbuf_destroy(ringbuf_t *ringbuf) {
  15   free(ringbuf->buf);
  16   free(ringbuf);
  17 }
  18
  19 size_t ringbuf_read(ringbuf_t *ringbuf,void *buf,size_t size) {
  20   // calculate free size
  21   size_t size_free = ringbuf->wpos>=ringbuf->rpos?ringbuf->wpos-ringbuf->rpos:ringbuf->wpos+ringbuf->size-ringbuf->rpos;
  22
  23   // check if buffer is big enough
  24   if (size>size_free) size = size_free;
  25   if (size==0) return 0;
  26
  27   // if isn't wrapped around at end just copy
  28   /// @todo Check this line
  29   if (ringbuf->rpos+size<ringbuf->size) memcpy(buf,ringbuf->buf+ringbuf->rpos,size);
  30   // else you have to do 2 copies
  31   else {
  32     size_t part1 = ringbuf->size-ringbuf->rpos;
  33     size_t part2 = size-part1;
  34     memcpy(buf,ringbuf->buf+ringbuf->rpos,part1);
  35     memcpy(buf+part1,ringbuf->buf,part2);
  36   }
  37
  38   // update read position
  39   ringbuf->rpos = (ringbuf->rpos+size)%ringbuf->size;
  40
  41   return size;
  42 }
  43
  44 size_t ringbuf_write(ringbuf_t *ringbuf,const void *buf,size_t size) {
  45   // calculate free size
  46   size_t size_free = ringbuf->rpos>ringbuf->wpos?ringbuf->rpos-ringbuf->wpos:ringbuf->rpos+ringbuf->size-ringbuf->rpos;
  47
  48   // check if buffer is big enough
  49   if (size>size_free) size = size_free;
  50   if (size==0) return 0;
  51
  52   // if isn't be wrapped around at end just copy
  53   /// @todo Check this line
  54   if (ringbuf->rpos+size<ringbuf->size) memcpy(ringbuf->buf+ringbuf->wpos,buf,size);
  55   // else you have to do 2 copies
  56   else {
  57     size_t part1 = ringbuf->size-ringbuf->wpos;
  58     size_t part2 = size-part1;
  59     memcpy(ringbuf->buf+ringbuf->wpos,buf,part1);
  60     memcpy(ringbuf->buf,buf+part1,part2);
  61   }
  62
  63   // update read position
  64   ringbuf->wpos = (ringbuf->wpos+size)%ringbuf->size;
  65
  66   return size;
  67 }