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$Log$ Revision 1.3 2008/01/31 09:38:15 haraldkipp Added return statement in main to avoid warnings with latest GCC.
Revision 1.2 2006/07/21 09:07:19 haraldkipp Use dev/board.h to determine output device.
Revision 1.1 2005/07/23 13:54:39 haraldkipp First check in
This sample demonstrates the usage of Nut/OS event queues. It further shows how an event queue can be used as a mutual exclusion semaphore.
Two additional threads are started, one with a higher and another one with a lower priority than the main thread.
The results are printed on the debug device. Each thread prints the current action in one of three columns. The first column is used by the highest priority, the last column by the lowest priority thread.
00001 00059 #include <cfg/os.h> 00060 00061 #include <stdio.h> 00062 #include <io.h> 00063 00064 #include <dev/board.h> 00065 00066 #include <sys/thread.h> 00067 #include <sys/timer.h> 00068 #include <sys/event.h> 00069 00070 /* 00071 * A global event queue, used as a mutex semaphore. 00072 */ 00073 static HANDLE mutex; 00074 00075 /* 00076 * High priority background thread. 00077 */ 00078 THREAD(High, arg) 00079 { 00080 NutThreadSetPriority(32); 00081 for(;;) { 00082 puts("Request"); 00083 if (NutEventWait(&mutex, 2000)) { 00084 puts("Timeout"); 00085 } 00086 else { 00087 puts("Acquired"); 00088 NutSleep(2500); 00089 puts("Release"); 00090 NutEventPost(&mutex); 00091 } 00092 NutSleep(1000); 00093 } 00094 } 00095 00096 /* 00097 * Low priority background thread. 00098 */ 00099 THREAD(Low, arg) 00100 { 00101 NutThreadSetPriority(96); 00102 for(;;) { 00103 puts(" Request"); 00104 if (NutEventWait(&mutex, 3000)) { 00105 puts(" Timeout"); 00106 } 00107 else { 00108 puts(" Acquired"); 00109 NutSleep(3500); 00110 puts(" Release"); 00111 NutEventPost(&mutex); 00112 } 00113 } 00114 } 00115 00116 /* 00117 * Main application routine. 00118 */ 00119 int main(void) 00120 { 00121 u_long baud = 115200; 00122 00123 /* 00124 * Register the UART device, open it, assign stdout to it and set 00125 * the baudrate. 00126 */ 00127 NutRegisterDevice(&DEV_DEBUG, 0, 0); 00128 freopen(DEV_DEBUG_NAME, "w", stdout); 00129 _ioctl(_fileno(stdout), UART_SETSPEED, &baud); 00130 00131 /* 00132 * Print title. 00133 */ 00134 puts("\nNut/OS Event Queue Demo"); 00135 puts("High Main Low "); 00136 00137 /* 00138 * Post an initial event. This will put the queue into signaled 00139 * state and immediately grant the next call to NutEventWait(). 00140 */ 00141 NutEventPost(&mutex); 00142 00143 /* 00144 * Start two background threads. 00145 */ 00146 NutThreadCreate("high", High, 0, 256); 00147 NutThreadCreate("low", Low, 0, 256); 00148 00149 for(;;) { 00150 puts(" Request"); 00151 if (NutEventWait(&mutex, 1000)) { 00152 puts(" Timeout"); 00153 } 00154 else { 00155 puts(" Acquired"); 00156 NutSleep(1500); 00157 puts(" Release"); 00158 NutEventPost(&mutex); 00159 } 00160 NutSleep(1000); 00161 } 00162 return 0; 00163 }