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729 | jermar | 1 | /* |
2 | * Copyright (C) 2006 Jakub Jermar |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
29 | /* |
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30 | * This implementation of FIFO stores values in a statically |
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31 | * allocated array created on each FIFO's initialization. |
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32 | * As such, these FIFOs have upper bound on number of values |
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33 | * they can store. Push and pop operations are done via accessing |
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34 | * the array through head and tail indices. Because of better |
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35 | * operation ordering in fifo_pop(), the access policy for these |
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36 | * two indices is to 'increment (mod size of FIFO) and use'. |
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37 | */ |
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38 | |||
39 | #ifndef __FIFO_H__ |
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40 | #define __FIFO_H__ |
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41 | |||
42 | #include <typedefs.h> |
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43 | |||
44 | /** Create and initialize FIFO. |
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45 | * |
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46 | * @param name Name of FIFO. |
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47 | * @param t Type of values stored in FIFO. |
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48 | * @param itms Number of items that can be stored in FIFO. |
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49 | */ |
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50 | #define FIFO_INITIALIZE(name, t, itms) \ |
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51 | struct { \ |
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52 | t fifo[(itms)]; \ |
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53 | count_t items; \ |
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54 | index_t head; \ |
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55 | index_t tail; \ |
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56 | } name = { \ |
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57 | .items = (itms), \ |
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58 | .head = 0, \ |
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59 | .tail = 0 \ |
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60 | } |
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61 | |||
62 | /** Pop value from head of FIFO. |
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63 | * |
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64 | * @param name FIFO name. |
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65 | * |
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66 | * @return Leading value in FIFO. |
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67 | */ |
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68 | #define fifo_pop(name) \ |
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752 | jermar | 69 | name.fifo[name.head = (name.head + 1) < name.items ? (name.head + 1) : 0] |
729 | jermar | 70 | |
71 | /** Push value to tail of FIFO. |
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72 | * |
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73 | * @param name FIFO name. |
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74 | * @param value Value to be appended to FIFO. |
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75 | * |
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76 | */ |
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77 | #define fifo_push(name, value) \ |
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752 | jermar | 78 | name.fifo[name.tail = (name.tail + 1) < name.items ? (name.tail + 1) : 0] = (value) |
729 | jermar | 79 | |
80 | #endif |