tx_sp.c

ThreadX优秀的硬实时操作系统.This Express Start Guide is designed to help you install and use ThreadX for the

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/*                                                                        */ 
/*            Copyright (c) 1996-2000 by Express Logic Inc.               */ 
/*                                                                        */ 
/*  This software is copyrighted by and is the sole property of Express   */ 
/*  Logic, Inc.  All rights, title, ownership, or other interests         */ 
/*  in the software remain the property of Express Logic, Inc.  This      */ 
/*  software may only be used in accordance with the corresponding        */ 
/*  license agreement.  Any unauthorized use, duplication, transmission,  */ 
/*  distribution, or disclosure of this software is expressly forbidden.  */ 
/*                                                                        */
/*  This Copyright notice may not be removed or modified without prior    */ 
/*  written consent of Express Logic, Inc.                                */ 
/*                                                                        */ 
/*  Express Logic, Inc. reserves the right to modify this software        */ 
/*  without notice.                                                       */ 
/*                                                                        */ 
/*  Express Logic, Inc.                                                   */
/*  11440 West Bernardo Court               [e-mail]         */
/*  Suite 366                               http://www.expresslogic.com   */
/*  San Diego, CA  92127                                                  */
/*                                                                        */
/**************************************************************************/


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/**                                                                       */ 
/** ThreadX Component                                                     */ 
/**                                                                       */
/**   Semaphore (SEM)                                                     */
/**                                                                       */
/**************************************************************************/
/**************************************************************************/

#define TX_SOURCE_CODE


/* Include necessary system files.  */

#include    "tx_api.h"
#include    "tx_thr.h"
#include    "tx_tim.h"
#include    "tx_sem.h"


/**************************************************************************/ 
/*                                                                        */ 
/*  FUNCTION                                               RELEASE        */ 
/*                                                                        */ 
/*    _tx_semaphore_put                                   PORTABLE C      */ 
/*                                                           3.0f         */ 
/*  AUTHOR                                                                */ 
/*                                                                        */ 
/*    William E. Lamie, Express Logic, Inc.                               */ 
/*                                                                        */ 
/*  DESCRIPTION                                                           */ 
/*                                                                        */ 
/*    This function puts an instance into the specified counting          */ 
/*    semaphore.                                                          */ 
/*                                                                        */ 
/*  INPUT                                                                 */ 
/*                                                                        */ 
/*    semaphore_ptr                     Pointer to semaphore control block*/ 
/*                                                                        */ 
/*  OUTPUT                                                                */ 
/*                                                                        */ 
/*    TX_SUCCESS                        Success completion status         */ 
/*                                                                        */ 
/*  CALLS                                                                 */ 
/*                                                                        */ 
/*    _tx_timer_deactivate              Deactivate timer routine          */ 
/*    _tx_thread_resume                 Resume thread service             */ 
/*    _tx_thread_system_return          Return to system routine          */ 
/*                                                                        */ 
/*  CALLED BY                                                             */ 
/*                                                                        */ 
/*    Application Code                                                    */ 
/*                                                                        */ 
/*  RELEASE HISTORY                                                       */ 
/*                                                                        */ 
/*    DATE              NAME                      DESCRIPTION             */ 
/*                                                                        */ 
/*  12-31-1996     William E. Lamie         Initial Version 3.0           */ 
/*  11-11-1997     William E. Lamie         Modified comment(s),          */ 
/*                                            resulting in version 3.0b.  */ 
/*  03-01-1998     William E. Lamie         Optimized post RESTORE        */ 
/*                                            processing, resulting in    */ 
/*                                            version 3.0d.               */ 
/*  01-01-1999     William E. Lamie         Modified comment(s),          */ 
/*                                            resulting in version 3.0e.  */ 
/*  11-01-1999     William E. Lamie         Modified comment(s),          */ 
/*                                            added logic to track events,*/ 
/*                                            resulting in version 3.0f.  */ 
/*                                                                        */ 
/**************************************************************************/ 
UINT    _tx_semaphore_put(TX_SEMAPHORE *semaphore_ptr)
{

TX_INTERRUPT_SAVE_AREA

REG_1   TX_THREAD   *thread_ptr;            /* Working thread pointer  */


    /* Disable interrupts to put an instance back to the semaphore.  */
    TX_DISABLE

    /* Log this kernel call.  */
    TX_EL_SEMAPHORE_PUT_INSERT

    /* Determine if there are any threads suspended on the semaphore.  */
    thread_ptr =  semaphore_ptr -> tx_semaphore_suspension_list;
    if (thread_ptr)
    {

        /* Remove the suspended thread from the list.  */

        /* See if this is the only suspended thread on the list.  */
        if (thread_ptr == thread_ptr -> tx_suspended_next)
        {

            /* Yes, the only suspended thread.  */

            /* Update the head pointer.  */
            semaphore_ptr -> tx_semaphore_suspension_list =  TX_NULL;
        }
        else
        {

            /* At least one more thread is on the same expiration list.  */

            /* Update the list head pointer.  */
            semaphore_ptr -> tx_semaphore_suspension_list =  thread_ptr -> tx_suspended_next;

            /* Update the links of the adjacent threads.  */
            (thread_ptr -> tx_suspended_next) -> tx_suspended_previous =  
                                                    thread_ptr -> tx_suspended_previous;
            (thread_ptr -> tx_suspended_previous) -> tx_suspended_next =
                                                    thread_ptr -> tx_suspended_next;
        } 
 
        /* Decrement the suspension count.  */
        semaphore_ptr -> tx_semaphore_suspended_count--;

        /* Prepare for resumption of the first thread.  */

        /* Clear cleanup routine to avoid timeout.  */
        thread_ptr -> tx_suspend_cleanup =  TX_NULL;

        /* Temporarily disable preemption.  */
        _tx_thread_preempt_disable++;

        /* Restore interrupts.  */
        TX_RESTORE

        /* Deactivate the timeout timer if necessary.  */
        if (thread_ptr -> tx_thread_timer.tx_list_head)
        {

            /* Deactivate the thread's timeout timer.  */
            _tx_timer_deactivate(&(thread_ptr -> tx_thread_timer));
        }
        else
        {

            /* Clear the remaining time to ensure timer doesn't get activated.  */
            thread_ptr -> tx_thread_timer.tx_remaining_ticks =  0;
        }

        /* Put return status into the thread control block.  */
        thread_ptr -> tx_suspend_status =  TX_SUCCESS;        

        /* Resume thread.  */
        if (_tx_thread_resume(thread_ptr))

            /* Preemption is required, transfer control back to 
               system.  */
            _tx_thread_system_return();

        /* Return success.  */
        return(TX_SUCCESS);
    }
    else
    {

        /* Increment the semaphore count.  */
        semaphore_ptr -> tx_semaphore_count++;
    }

    /* Restore interrupts.  */
    TX_RESTORE

    /* Return successful completion status.  */
    return(TX_SUCCESS);
}