From 633c646ab36368caf6eaeedd326d9f1835196afd Mon Sep 17 00:00:00 2001 From: henryk Date: Tue, 6 Nov 2007 20:26:48 +0000 Subject: Initial import of FreeRTOS code for OpenPICC git-svn-id: https://svn.openpcd.org:2342/trunk@311 6dc7ffe9-61d6-0310-9af1-9938baff3ed1 --- openpicc/os/core/include/semphr.h | 291 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 291 insertions(+) create mode 100644 openpicc/os/core/include/semphr.h (limited to 'openpicc/os/core/include/semphr.h') diff --git a/openpicc/os/core/include/semphr.h b/openpicc/os/core/include/semphr.h new file mode 100644 index 0000000..acdd022 --- /dev/null +++ b/openpicc/os/core/include/semphr.h @@ -0,0 +1,291 @@ +/* + FreeRTOS.org V4.2.1 - Copyright (C) 2003-2007 Richard Barry. + + This file is part of the FreeRTOS.org distribution. + + FreeRTOS.org is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + FreeRTOS.org is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with FreeRTOS.org; if not, write to the Free Software + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + + A special exception to the GPL can be applied should you wish to distribute + a combined work that includes FreeRTOS.org, without being obliged to provide + the source code for any proprietary components. See the licensing section + of http://www.FreeRTOS.org for full details of how and when the exception + can be applied. + + *************************************************************************** + See http://www.FreeRTOS.org for documentation, latest information, license + and contact details. Please ensure to read the configuration and relevant + port sections of the online documentation. + + Also see http://www.SafeRTOS.com for an IEC 61508 compliant version along + with commercial development and support options. + *************************************************************************** +*/ + +#include "queue.h" + +#ifndef SEMAPHORE_H +#define SEMAPHORE_H + +typedef xQueueHandle xSemaphoreHandle; + +#define semBINARY_SEMAPHORE_QUEUE_LENGTH ( ( unsigned portCHAR ) 1 ) +#define semSEMAPHORE_QUEUE_ITEM_LENGTH ( ( unsigned portCHAR ) 0 ) +#define semGIVE_BLOCK_TIME ( ( portTickType ) 0 ) + + +/** + * semphr. h + * 
vSemaphoreCreateBinary( xSemaphoreHandle xSemaphore )
+ * + * Macro that implements a semaphore by using the existing queue mechanism. + * The queue length is 1 as this is a binary semaphore. The data size is 0 + * as we don't want to actually store any data - we just want to know if the + * queue is empty or full. + * + * @param xSemaphore Handle to the created semaphore. Should be of type xSemaphoreHandle. + * + * Example usage: + 
+ xSemaphoreHandle xSemaphore;
+
+ void vATask( void * pvParameters )
+ {
+    // Semaphore cannot be used before a call to vSemaphoreCreateBinary ().
+    // This is a macro so pass the variable in directly.
+    vSemaphoreCreateBinary( xSemaphore );
+
+    if( xSemaphore != NULL )
+    {
+        // The semaphore was created successfully.
+        // The semaphore can now be used.  
+    }
+ }
+
+ * \defgroup vSemaphoreCreateBinary vSemaphoreCreateBinary + * \ingroup Semaphores + */ +#define vSemaphoreCreateBinary( xSemaphore ) { \ + xSemaphore = xQueueCreate( ( unsigned portCHAR ) 1, semSEMAPHORE_QUEUE_ITEM_LENGTH ); \ + if( xSemaphore != NULL ) \ + { \ + xSemaphoreGive( xSemaphore ); \ + } \ + } + +/** + * semphr. h + * xSemaphoreTake( + * xSemaphoreHandle xSemaphore, + * portTickType xBlockTime + * ) + * + * Macro to obtain a semaphore. The semaphore must of been created using + * vSemaphoreCreateBinary (). + * + * @param xSemaphore A handle to the semaphore being obtained. This is the + * handle returned by vSemaphoreCreateBinary (); + * + * @param xBlockTime The time in ticks to wait for the semaphore to become + * available. The macro portTICK_RATE_MS can be used to convert this to a + * real time. A block time of zero can be used to poll the semaphore. + * + * @return pdTRUE if the semaphore was obtained. pdFALSE if xBlockTime + * expired without the semaphore becoming available. + * + * Example usage: + 
+ xSemaphoreHandle xSemaphore = NULL;
+
+ // A task that creates a semaphore.
+ void vATask( void * pvParameters )
+ {
+    // Create the semaphore to guard a shared resource.
+    vSemaphoreCreateBinary( xSemaphore );
+ }
+
+ // A task that uses the semaphore.
+ void vAnotherTask( void * pvParameters )
+ {
+    // ... Do other things.
+
+    if( xSemaphore != NULL )
+    {
+        // See if we can obtain the semaphore.  If the semaphore is not available
+        // wait 10 ticks to see if it becomes free.	
+        if( xSemaphoreTake( xSemaphore, ( portTickType ) 10 ) == pdTRUE )
+        {
+            // We were able to obtain the semaphore and can now access the
+            // shared resource.
+
+            // ...
+
+            // We have finished accessing the shared resource.  Release the 
+            // semaphore.
+            xSemaphoreGive( xSemaphore );
+        }
+        else
+        {
+            // We could not obtain the semaphore and can therefore not access
+            // the shared resource safely.
+        }
+    }
+ }
+
+ * \defgroup xSemaphoreTake xSemaphoreTake + * \ingroup Semaphores + */ +#define xSemaphoreTake( xSemaphore, xBlockTime ) xQueueReceive( ( xQueueHandle ) xSemaphore, NULL, xBlockTime ) + +/** + * semphr. h + * 
xSemaphoreGive( xSemaphoreHandle xSemaphore )
+ * + * Macro to release a semaphore. The semaphore must of been created using + * vSemaphoreCreateBinary (), and obtained using sSemaphoreTake (). + * + * This must not be used from an ISR. See xSemaphoreGiveFromISR () for + * an alternative which can be used from an ISR. + * + * @param xSemaphore A handle to the semaphore being released. This is the + * handle returned by vSemaphoreCreateBinary (); + * + * @return pdTRUE if the semaphore was released. pdFALSE if an error occurred. + * Semaphores are implemented using queues. An error can occur if there is + * no space on the queue to post a message - indicating that the + * semaphore was not first obtained correctly. + * + * Example usage: + 
+ xSemaphoreHandle xSemaphore = NULL;
+
+ void vATask( void * pvParameters )
+ {
+    // Create the semaphore to guard a shared resource.
+    vSemaphoreCreateBinary( xSemaphore );
+
+    if( xSemaphore != NULL )
+    {
+        if( xSemaphoreGive( xSemaphore ) != pdTRUE )
+        {
+            // We would expect this call to fail because we cannot give
+            // a semaphore without first "taking" it!
+        }
+
+        // Obtain the semaphore - don't block if the semaphore is not
+        // immediately available.
+        if( xSemaphoreTake( xSemaphore, ( portTickType ) 0 ) )
+        {
+            // We now have the semaphore and can access the shared resource.
+
+            // ...
+
+            // We have finished accessing the shared resource so can free the
+            // semaphore.
+            if( xSemaphoreGive( xSemaphore ) != pdTRUE )
+            {
+                // We would not expect this call to fail because we must have
+                // obtained the semaphore to get here.
+            }
+        }
+    }
+ }
+
+ * \defgroup xSemaphoreGive xSemaphoreGive + * \ingroup Semaphores + */ +#define xSemaphoreGive( xSemaphore ) xQueueSend( ( xQueueHandle ) xSemaphore, NULL, semGIVE_BLOCK_TIME ) + +/** + * semphr. h + * 
+ xSemaphoreGiveFromISR( 
+                          xSemaphoreHandle xSemaphore, 
+                          portSHORT sTaskPreviouslyWoken 
+                      )
+ * + * Macro to release a semaphore. The semaphore must of been created using + * vSemaphoreCreateBinary (), and obtained using xSemaphoreTake (). + * + * This macro can be used from an ISR. + * + * @param xSemaphore A handle to the semaphore being released. This is the + * handle returned by vSemaphoreCreateBinary (); + * + * @param sTaskPreviouslyWoken This is included so an ISR can make multiple calls + * to xSemaphoreGiveFromISR () from a single interrupt. The first call + * should always pass in pdFALSE. Subsequent calls should pass in + * the value returned from the previous call. See the file serial .c in the + * PC port for a good example of using xSemaphoreGiveFromISR (). + * + * @return pdTRUE if a task was woken by releasing the semaphore. This is + * used by the ISR to determine if a context switch may be required following + * the ISR. + * + * Example usage: + 
+ #define LONG_TIME 0xffff
+ #define TICKS_TO_WAIT	10
+ xSemaphoreHandle xSemaphore = NULL;
+
+ // Repetitive task.
+ void vATask( void * pvParameters )
+ {
+    for( ;; )
+    {
+        // We want this task to run every 10 ticks or a timer.  The semaphore 
+        // was created before this task was started
+
+        // Block waiting for the semaphore to become available.
+        if( xSemaphoreTake( xSemaphore, LONG_TIME ) == pdTRUE )
+        {
+            // It is time to execute.
+
+            // ...
+
+            // We have finished our task.  Return to the top of the loop where
+            // we will block on the semaphore until it is time to execute 
+            // again.
+        }
+    }
+ }
+
+ // Timer ISR
+ void vTimerISR( void * pvParameters )
+ {
+ static unsigned portCHAR ucLocalTickCount = 0;
+
+    // A timer tick has occurred.
+
+    // ... Do other time functions.
+
+    // Is it time for vATask () to run?
+    ucLocalTickCount++;
+    if( ucLocalTickCount >= TICKS_TO_WAIT )
+    {
+        // Unblock the task by releasing the semaphore.
+        xSemaphoreGive( xSemaphore );
+
+        // Reset the count so we release the semaphore again in 10 ticks time.
+        ucLocalTickCount = 0;
+    }
+ }
+
+ * \defgroup xSemaphoreGiveFromISR xSemaphoreGiveFromISR + * \ingroup Semaphores + */ +#define xSemaphoreGiveFromISR( xSemaphore, xTaskPreviouslyWoken ) xQueueSendFromISR( ( xQueueHandle ) xSemaphore, NULL, xTaskPreviouslyWoken ) + + +#endif -- cgit v1.2.3