1 | /*
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2 | Copyright (c) 2011 Arduino. All right reserved.
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3 |
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4 | This library is free software; you can redistribute it and/or
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5 | modify it under the terms of the GNU Lesser General Public
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6 | License as published by the Free Software Foundation; either
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7 | version 2.1 of the License, or (at your option) any later version.
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8 |
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9 | This library is distributed in the hope that it will be useful,
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10 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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12 | See the GNU Lesser General Public License for more details.
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13 |
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14 | You should have received a copy of the GNU Lesser General Public
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15 | License along with this library; if not, write to the Free Software
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16 | Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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17 | */
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18 |
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19 | #include "RingBuffer.h"
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20 | #include <string.h>
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21 |
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22 | RingBuffer::RingBuffer( void )
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23 | {
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24 | memset( _aucBuffer, 0, SERIAL_BUFFER_SIZE ) ;
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25 | clear();
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26 | }
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27 |
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28 | void RingBuffer::store_char( uint8_t c )
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29 | {
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30 | int i = nextIndex(_iHead);
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31 |
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32 | // if we should be storing the received character into the location
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33 | // just before the tail (meaning that the head would advance to the
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34 | // current location of the tail), we're about to overflow the buffer
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35 | // and so we don't write the character or advance the head.
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36 | if ( i != _iTail )
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37 | {
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38 | _aucBuffer[_iHead] = c ;
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39 | _iHead = i ;
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40 | }
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41 | }
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42 |
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43 | void RingBuffer::clear()
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44 | {
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45 | _iHead = 0;
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46 | _iTail = 0;
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47 | }
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48 |
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49 | int RingBuffer::read_char()
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50 | {
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51 | if(_iTail == _iHead)
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52 | return -1;
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53 |
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54 | uint8_t value = _aucBuffer[_iTail];
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55 | _iTail = nextIndex(_iTail);
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56 |
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57 | return value;
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58 | }
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59 |
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60 | int RingBuffer::available()
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61 | {
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62 | int delta = _iHead - _iTail;
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63 |
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64 | if(delta < 0)
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65 | return SERIAL_BUFFER_SIZE + delta;
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66 | else
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67 | return delta;
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68 | }
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69 |
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70 | int RingBuffer::peek()
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71 | {
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72 | if(_iTail == _iHead)
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73 | return -1;
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74 |
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75 | return _aucBuffer[_iTail];
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76 | }
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77 |
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78 | int RingBuffer::nextIndex(int index)
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79 | {
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80 | return (uint32_t)(index + 1) % SERIAL_BUFFER_SIZE;
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81 | }
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82 |
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83 | bool RingBuffer::isFull()
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84 | {
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85 | return (nextIndex(_iHead) == _iTail);
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86 | }
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