chibi/chb_buf.c

   1 /*******************************************************************
   2     Copyright (C) 2009 FreakLabs
   3     All rights reserved.
   4
   5     Redistribution and use in source and binary forms, with or without
   6     modification, are permitted provided that the following conditions
   7     are met:
   8
   9     1. Redistributions of source code must retain the above copyright
  10        notice, this list of conditions and the following disclaimer.
  11     2. Redistributions in binary form must reproduce the above copyright
  12        notice, this list of conditions and the following disclaimer in the
  13        documentation and/or other materials provided with the distribution.
  14     3. Neither the name of the the copyright holder nor the names of its contributors
  15        may be used to endorse or promote products derived from this software
  16        without specific prior written permission.
  17
  18     THIS SOFTWARE IS PROVIDED BY THE THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
  19     ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20     IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21     ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  22     FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23     DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24     OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26     LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27     OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28     SUCH DAMAGE.
  29
  30     Originally written by Christopher Wang aka Akiba.
  31     Please post support questions to the FreakLabs forum.
  32
  33 *******************************************************************/
  34 #include <stdio.h>
  35 #include "chb_buf.h"
  36
  37 static U8 chb_buf[CHB_BUF_SZ];
  38 static U8 rd_ptr, wr_ptr, len;
  39
  40 /**************************************************************************/
  41 /*!
  42
  43 */
  44 /**************************************************************************/
  45 void chb_buf_init()
  46 {
  47     rd_ptr = 0;
  48     wr_ptr = 0;
  49     len = 0;
  50 }
  51
  52 /**************************************************************************/
  53 /*!
  54
  55 */
  56 /**************************************************************************/
  57 void chb_buf_write(U8 data)
  58 {
  59     chb_buf[wr_ptr] = data;
  60     wr_ptr = (wr_ptr + 1) % CHB_BUF_SZ;
  61     len++;
  62 }
  63
  64 /**************************************************************************/
  65 /*!
  66
  67 */
  68 /**************************************************************************/
  69 U8 chb_buf_read()
  70 {
  71     U8 data;
  72
  73     data = chb_buf[rd_ptr];
  74     rd_ptr = (rd_ptr + 1) % CHB_BUF_SZ;
  75     len--;
  76     return data;
  77 }