core/usbcdc/cdc_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 /**************************************************************************/
  35 /*!
  36     @file     cdc_buf.c
  37     @author   Christopher Wang (Freaklabs)
  38               Modified by: K. Townsend (microBuilder.eu)
  39     @date     19 May 2010
  40
  41     Original code taken from the FreakUSB Open Source USB Device Stack
  42     http://freaklabs.org/index.php/FreakUSB-Open-Source-USB-Device-Stack.html
  43
  44     If it works well, you can thank Akiba at Freaklabs.  If it fails
  45     miserably, you can blame me (since parts of it it were rather
  46     ungraciously modified). :-)
  47
  48 */
  49 /**************************************************************************/
  50
  51 #include "cdc_buf.h"
  52
  53 static cdc_buffer_t cdcfifo;
  54
  55 /**************************************************************************/
  56 /*!
  57   Gets a pointer to the fifo buffer
  58 */
  59 /**************************************************************************/
  60 cdc_buffer_t *cdcGetBuffer()
  61 {
  62   return &cdcfifo;
  63 }
  64
  65 /**************************************************************************/
  66 /*!
  67   Initialises the RX FIFO buffer
  68 */
  69 /**************************************************************************/
  70 void cdcBufferInit()
  71 {
  72   cdcfifo.len = 0;
  73 }
  74
  75 /**************************************************************************/
  76 /*!
  77   Read one byte out of the RX buffer. This function will return the byte
  78   located at the array index of the read pointer, and then increment the
  79   read pointer index.  If the read pointer exceeds the maximum buffer
  80   size, it will roll over to zero.
  81 */
  82 /**************************************************************************/
  83 uint8_t cdcBufferRead()
  84 {
  85   uint8_t data;
  86
  87   data = cdcfifo.buf[cdcfifo.rd_ptr];
  88   cdcfifo.rd_ptr = (cdcfifo.rd_ptr + 1) % CFG_USBCDC_BUFFERSIZE;
  89   cdcfifo.len--;
  90   return data;
  91 }
  92
  93 /**************************************************************************/
  94 /*!
  95   Reads x bytes from cdc buffer
  96  */
  97 /**************************************************************************/
  98 uint32_t cdcBufferReadLen(uint8_t* buf, uint32_t len)
  99 {
 100   uint32_t counter, actual;
 101   counter = actual = 0;
 102
 103   while(counter != len)
 104   {
 105     // Make sure we don't exceed buffer limits
 106     if (cdcfifo.len > 0)
 107     {
 108       buf[counter] = cdcBufferRead();
 109       actual++;
 110       counter++;
 111     }
 112     else
 113     {
 114       return actual;
 115     }
 116   }
 117
 118   return actual;
 119 }
 120
 121 /**************************************************************************/
 122 /*!
 123   Write one byte into the RX buffer. This function will write one
 124   byte into the array index specified by the write pointer and increment
 125   the write index. If the write index exceeds the max buffer size, then it
 126   will roll over to zero.
 127 */
 128 /**************************************************************************/
 129 void cdcBufferWrite(uint8_t data)
 130 {
 131   cdcfifo.buf[cdcfifo.wr_ptr] = data;
 132   cdcfifo.wr_ptr = (cdcfifo.wr_ptr + 1) % CFG_USBCDC_BUFFERSIZE;
 133   cdcfifo.len++;
 134 }
 135
 136 /**************************************************************************/
 137 /*!
 138     Clear the fifo read and write pointers and set the length to zero.
 139 */
 140 /**************************************************************************/
 141 void cdcBufferClearFIFO()
 142 {
 143   cdcfifo.rd_ptr = 0;
 144   cdcfifo.wr_ptr = 0;
 145   cdcfifo.len = 0;
 146 }
 147
 148 /**************************************************************************/
 149 /*!
 150     Check whether there is any data pending on the RX buffer.
 151 */
 152 /**************************************************************************/
 153 uint8_t cdcBufferDataPending()
 154 {
 155   if (cdcfifo.len != 0)
 156   {
 157     return 1;
 158   }
 159
 160   return 0;
 161 }