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1 #ifndef CYGONCE_KERNEL_SEMA_HXX |
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2 #define CYGONCE_KERNEL_SEMA_HXX |
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3 |
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4 //========================================================================== |
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5 // |
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6 // sema.hxx |
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7 // |
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8 // Semaphore class declarations |
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9 // |
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10 //========================================================================== |
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11 //####COPYRIGHTBEGIN#### |
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12 // |
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13 // ------------------------------------------- |
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14 // The contents of this file are subject to the Cygnus eCos Public License |
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15 // Version 1.0 (the "License"); you may not use this file except in |
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16 // compliance with the License. You may obtain a copy of the License at |
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17 // http://sourceware.cygnus.com/ecos |
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18 // |
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19 // Software distributed under the License is distributed on an "AS IS" |
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20 // basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the |
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21 // License for the specific language governing rights and limitations under |
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22 // the License. |
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23 // |
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24 // The Original Code is eCos - Embedded Cygnus Operating System, released |
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25 // September 30, 1998. |
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26 // |
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27 // The Initial Developer of the Original Code is Cygnus. Portions created |
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28 // by Cygnus are Copyright (C) 1998,1999 Cygnus Solutions. All Rights Reserved. |
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29 // ------------------------------------------- |
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30 // |
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31 //####COPYRIGHTEND#### |
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32 //========================================================================== |
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33 //#####DESCRIPTIONBEGIN#### |
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34 // |
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35 // Author(s): nickg |
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36 // Contributors: nickg |
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37 // Date: 1997-09-09 |
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38 // Purpose: Define Semaphore class interfaces |
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39 // Description: The classes defined here provide the APIs for binary |
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40 // and counting semaphores. |
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41 // Usage: #include <cyg/kernel/sema.hxx> |
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42 // |
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43 // |
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44 //####DESCRIPTIONEND#### |
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45 // |
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46 //========================================================================== |
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47 |
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48 #include <cyg/kernel/ktypes.h> |
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49 #include <cyg/infra/cyg_ass.h> // assertion macros |
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50 #include <cyg/kernel/thread.hxx> |
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51 |
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52 // ------------------------------------------------------------------------- |
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53 // Binary semaphore. This has only two states: posted and not-posted. |
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54 |
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55 class Cyg_Binary_Semaphore |
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56 { |
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57 cyg_bool state; // The binary semaphore state |
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58 |
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59 Cyg_ThreadQueue queue; // Queue of waiting threads |
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60 |
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61 public: |
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62 |
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63 CYGDBG_DEFINE_CHECK_THIS |
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64 |
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65 Cyg_Binary_Semaphore( // Constructor |
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66 cyg_bool init_state = false // Initial state value |
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67 ); |
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68 |
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69 ~Cyg_Binary_Semaphore(); // Destructor |
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70 |
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71 cyg_bool wait(); // Wait until state == true |
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72 |
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73 cyg_bool trywait(); // Set state false if possible |
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74 |
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75 void post(); // Increment count |
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76 |
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77 cyg_bool posted(); // Get current state |
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78 |
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79 }; |
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80 |
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81 // ------------------------------------------------------------------------- |
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82 // Counting semaphore. This implements the usual counter based semaphore. |
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83 |
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84 class Cyg_Counting_Semaphore |
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85 { |
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86 cyg_count32 count; // The semaphore count |
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87 |
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88 Cyg_ThreadQueue queue; // Queue of waiting threads |
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89 |
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90 public: |
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91 |
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92 CYGDBG_DEFINE_CHECK_THIS |
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93 |
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94 Cyg_Counting_Semaphore( // Constructor |
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95 cyg_count32 init_count = 0 // Initial count value |
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96 ); |
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97 |
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98 ~Cyg_Counting_Semaphore(); // Destructor |
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99 |
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100 cyg_bool wait(); // Wait until decrement |
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101 |
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102 #ifdef CYGFUN_KERNEL_THREADS_TIMER |
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103 cyg_bool wait( cyg_tick_count timeout ); |
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104 #endif // Wait until decrement or timeout |
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105 |
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106 cyg_bool trywait(); // Try to decrement |
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107 |
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108 void post(); // Increment count |
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109 |
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110 cyg_count32 peek(); // Get current count value |
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111 |
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112 inline |
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113 cyg_bool waiting() // Is anyone waiting? |
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114 { |
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115 return !queue.empty(); |
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116 } |
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117 |
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118 }; |
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119 |
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120 // ------------------------------------------------------------------------- |
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121 #endif // ifndef CYGONCE_KERNEL_SEMA_HXX |
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122 // EOF sema.hxx |
