circularBuff.cpp

00001 #include "circularBuff.h"
00002 
00003 int circ_buf_rst(circ_buf_t * cbuf) 
00004 {
00005     int r = -1;
00006 
00007     if(cbuf)
00008     {
00009         cbuf->head = 0;
00010         cbuf->tail = 0;
00011         r = 0;
00012     }
00013 
00014     return r;
00015 }
00016 
00017 bool circ_buf_empty(circ_buf_t cbuf)
00018 {
00019     // We define empty as head == tail
00020     return (cbuf.head == cbuf.tail);
00021 }
00022 
00023 bool circ_buf_full(circ_buf_t cbuf)
00024 {
00025     // We determine "full" case by head being one position behind the tail
00026     // Note that this means we are wasting one space in the buffer!
00027     // Instead, you could have an "empty" flag and determine buffer full that way
00028     return ((cbuf.head + 1) % cbuf.size) == cbuf.tail;
00029 }
00030 
00031 int circ_buf_put(circ_buf_t * cbuf, uint8_t data)
00032 {
00033     int r = -1;
00034 
00035     if(cbuf)
00036     {
00037         cbuf->buffer[cbuf->head] = data;
00038         cbuf->head = (cbuf->head + 1) % cbuf->size;
00039 
00040         if(cbuf->head == cbuf->tail)
00041         {
00042             cbuf->tail = (cbuf->tail + 1) % cbuf->size;
00043         }
00044 
00045         r = 0;
00046     }
00047 
00048     return r;
00049 }
00050 
00051 int circ_buf_get(circ_buf_t * cbuf, uint8_t * data)
00052 {
00053     int r = -1;
00054 
00055     if(cbuf && data && !circ_buf_empty(*cbuf))
00056     {
00057         *data = cbuf->buffer[cbuf->tail];
00058         cbuf->tail = (cbuf->tail + 1) % cbuf->size;
00059 
00060         r = 0;
00061     }
00062 
00063     return r;
00064 }