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//==========================================================================

//

//      sem.cxx

//

//      POSIX semaphore implementation

//

//==========================================================================

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

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//####ECOSGPLCOPYRIGHTEND####

//==========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):           nickg

// Contributors:        nickg

// Date:                2000-03-27

// Purpose:             POSIX semaphore implementation

// Description:         This file contains the implementation of the POSIX semaphore

//                      functions.

//              

//              

//

//####DESCRIPTIONEND####

//

//==========================================================================

#include <pkgconf/hal.h>

#include <pkgconf/kernel.h>

#include <pkgconf/posix.h>

#include <cyg/kernel/ktypes.h>          // base kernel types

#include <cyg/infra/cyg_trac.h>         // tracing macros

#include <cyg/infra/cyg_ass.h>          // assertion macros

#include <semaphore.h>                  // our header

#include "pprivate.h"                   // POSIX private header

#include <cyg/kernel/thread.hxx>        // Kernel threads

#include <cyg/kernel/thread.inl>        // Cyg_ThreadQueue::empty()

#include <cyg/kernel/sema.hxx>          // Kernel semaphores

// -------------------------------------------------------------------------

// Internal definitions

// Handle entry to a pthread package function. 

#define SEMA_ENTRY() CYG_REPORT_FUNCTYPE( "returning %d" );

// Do a semaphore package defined return. This requires the error code

// to be placed in errno, and if it is non-zero, -1 returned as the

// result of the function. This also gives us a place to put any

// generic tidyup handling needed for things like signal delivery and

// cancellation.

#define SEMA_RETURN(err)                        \

CYG_MACRO_START                                 \

    int __retval = 0;                           \

    if( err != 0 ) __retval = -1, errno = err;  \

    CYG_REPORT_RETVAL( __retval );              \

    return __retval;                            \

CYG_MACRO_END

//-----------------------------------------------------------------------------

// new operator to allow us to invoke the Cyg_Thread constructor on the

// user's semaphore object.

inline void *operator new(size_t size,  void *ptr) { return (void *)ptr; };

// -------------------------------------------------------------------------

// Initialize semaphore to value.

// pshared is not supported under eCos.

externC int sem_init  (sem_t *sem, int pshared, unsigned int value)

{

    SEMA_ENTRY();

    if( value > SEM_VALUE_MAX )

        SEMA_RETURN(EINVAL);

    Cyg_Counting_Semaphore *sema;

    sema = new((void *)sem) Cyg_Counting_Semaphore(value);

    sema=sema;

    SEMA_RETURN(0);

}

// -------------------------------------------------------------------------

// Destroy the semaphore.

externC int sem_destroy  (sem_t *sem)

{

    SEMA_ENTRY();

    Cyg_Counting_Semaphore *sema = (Cyg_Counting_Semaphore *)sem;

    // Check that the semaphore has no waiters

    if( sema->waiting() )

        SEMA_RETURN(EBUSY);

    // Call the destructor

    sema->~Cyg_Counting_Semaphore();

    SEMA_RETURN(0);

}

// -------------------------------------------------------------------------

// Decrement value if >0 or wait for a post.

externC int sem_wait  (sem_t *sem)

{

    int retval = 0;

    SEMA_ENTRY();

#ifdef CYGPKG_POSIX_PTHREAD

    // check for cancellation first.

    pthread_testcancel();

#endif

    Cyg_Counting_Semaphore *sema = (Cyg_Counting_Semaphore *)sem;

    if( !sema->wait() ) retval = EINTR;

#ifdef CYGPKG_POSIX_PTHREAD

    // check if we were woken because we were being cancelled

    pthread_testcancel();

#endif

    SEMA_RETURN(retval);

}

// -------------------------------------------------------------------------

// Decrement value if >0, return -1 if not.

externC int sem_trywait  (sem_t *sem)

{

    int retval = 0;

    SEMA_ENTRY();

    Cyg_Counting_Semaphore *sema = (Cyg_Counting_Semaphore *)sem;

    if( !sema->trywait() ) retval = EAGAIN;

    SEMA_RETURN(retval);

}

// -------------------------------------------------------------------------

// Increment value and wake a waiter if one is present.

externC int sem_post  (sem_t *sem)

{

    SEMA_ENTRY();

    Cyg_Counting_Semaphore *sema = (Cyg_Counting_Semaphore *)sem;

    sema->post();

    SEMA_RETURN(0);

}

// -------------------------------------------------------------------------

// Get current value

externC int sem_getvalue  (sem_t *sem, int *sval)

{

    SEMA_ENTRY();

    Cyg_Counting_Semaphore *sema = (Cyg_Counting_Semaphore *)sem;

    *sval = sema->peek();

    CYG_REPORT_RETVAL( 0 );

    return 0;

}

// -------------------------------------------------------------------------

// Open an existing named semaphore, or create it.

externC sem_t *sem_open  (const char *name, int oflag, ...)

{

    SEMA_ENTRY();

    errno = ENOSYS;

    CYG_REPORT_RETVAL( SEM_FAILED );

    return SEM_FAILED;

}

// -------------------------------------------------------------------------

// Close descriptor for semaphore.

externC int sem_close  (sem_t *sem)

{

    SEMA_ENTRY();

    SEMA_RETURN(ENOSYS);

}

// -------------------------------------------------------------------------

// Remove named semaphore

externC int sem_unlink  (const char *name)

{

    SEMA_ENTRY();

    SEMA_RETURN(ENOSYS);

}

// -------------------------------------------------------------------------

// EOF sem.cxx