?? smc.c
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/* */
/* HISTORY */
/* */
/* DATE REMARKS */
/* */
/* 03-01-1993 Created initial version 1.0 */
/* 04-19-1993 Verified version 1.0 */
/* 03-01-1994 Changed function interfaces to */
/* match those in prototype, */
/* added register options, changed */
/* protection logic to reduce */
/* overhead, resulting in */
/* version 1.1 */
/* */
/* 03-18-1994 Verified version 1.1 */
/* */
/*************************************************************************/
STATUS SMC_Delete_Semaphore(NU_SEMAPHORE *semaphore_ptr)
{
R1 SM_SCB *semaphore; /* Semaphore control blk ptr */
SM_SUSPEND *suspend_ptr; /* Suspend block pointer */
SM_SUSPEND *next_ptr; /* Next suspend block */
STATUS preempt; /* Status for resume call */
NU_SUPERV_USER_VARIABLES
/* Switch to supervisor mode */
NU_SUPERVISOR_MODE();
/* Move input semaphore pointer into internal pointer. */
semaphore = (SM_SCB *) semaphore_ptr;
#ifdef NU_ENABLE_STACK_CHECK
/* Call stack checking function to check for an overflow condition. */
TCT_Check_Stack();
#endif
#ifdef NU_ENABLE_HISTORY
/* Make an entry that corresponds to this function in the system history
log. */
HIC_Make_History_Entry(NU_DELETE_SEMAPHORE_ID, (UNSIGNED) semaphore,
(UNSIGNED) 0, (UNSIGNED) 0);
#endif
/* Protect against access to the semaphore. */
TCT_System_Protect();
#ifdef INCLUDE_PROVIEW
_RTProf_DumpSema(RT_PROF_DELETE_SEMAPHORE,semaphore, RT_PROF_OK);
#endif
/* Clear the semaphore ID. */
semaphore -> sm_id = 0;
/* Release protection. */
TCT_Unprotect();
/* Protect against access to the list of created semaphores. */
TCT_Protect(&SMD_List_Protect);
/* Remove the semaphore from the list of created semaphores. */
CSC_Remove_From_List(&SMD_Created_Semaphores_List,
&(semaphore -> sm_created));
/* Decrement the total number of created semaphores. */
SMD_Total_Semaphores--;
/* Pickup the suspended task pointer list. */
suspend_ptr = semaphore -> sm_suspension_list;
/* Walk the chain task(s) currently suspended on the semaphore. */
preempt = 0;
while (suspend_ptr)
{
/* Protect against system access. */
TCT_System_Protect();
/* Resume the suspended task. Insure that the status returned is
NU_SEMAPHORE_DELETED. */
suspend_ptr -> sm_return_status = NU_SEMAPHORE_DELETED;
/* Point to the next suspend structure in the link. */
next_ptr = (SM_SUSPEND *) (suspend_ptr -> sm_suspend_link.cs_next);
/* Resume the specified task. */
preempt = preempt |
TCC_Resume_Task((NU_TASK *) suspend_ptr -> sm_suspended_task,
NU_SEMAPHORE_SUSPEND);
/* Determine if the next is the same as the current pointer. */
if (next_ptr == semaphore -> sm_suspension_list)
/* Clear the suspension pointer to signal the end of the list
traversal. */
suspend_ptr = NU_NULL;
else
/* Move the next pointer into the suspend block pointer. */
suspend_ptr = next_ptr;
/* Modify current protection. */
TCT_Set_Current_Protect(&SMD_List_Protect);
/* Clear the system protection. */
TCT_System_Unprotect();
}
/* Determine if preemption needs to occur. */
if (preempt)
/* Transfer control to system to facilitate preemption. */
TCT_Control_To_System();
/* Release protection against access to the list of created semaphores. */
TCT_Unprotect();
/* Return to user mode */
NU_USER_MODE();
/* Return a successful completion. */
return(NU_SUCCESS);
}
/*************************************************************************/
/* */
/* FUNCTION */
/* */
/* SMC_Obtain_Semaphore */
/* */
/* DESCRIPTION */
/* */
/* This function obtains an instance of the semaphore. An instance */
/* corresponds to decrementing the counter by 1. If the counter is */
/* greater than zero at the time of this call, this function can be */
/* completed immediately. Otherwise, suspension is possible. */
/* */
/* CALLED BY */
/* */
/* Application */
/* SMCE_Obtain_Semaphore Error checking shell */
/* */
/* CALLS */
/* */
/* CSC_Place_On_List Place on suspend list */
/* CSC_Priority_Place_On_List Place on priority list */
/* [HIC_Make_History_Entry] Make entry in history log */
/* TCC_Suspend_Task Suspend calling task */
/* TCC_Task_Priority Obtain task's priority */
/* [TCT_Check_Stack] Stack checking function */
/* TCT_Current_Thread Pickup current thread pointer*/
/* TCT_System_Protect Protect semaphore */
/* TCT_Unprotect Release protection */
/* */
/* INPUTS */
/* */
/* semaphore_ptr Semaphore control block ptr */
/* suspend Suspension option if full */
/* */
/* OUTPUTS */
/* */
/* NU_SUCCESS If service is successful */
/* NU_UNAVAILABLE If an instance of the */
/* semaphore is not available */
/* NU_TIMEOUT If timeout on service */
/* NU_SEMAPHORE_DELETED If semaphore deleted during */
/* suspension */
/* NU_SEMAPHORE_RESET If semaphore reset during */
/* suspension */
/* */
/* HISTORY */
/* */
/* DATE REMARKS */
/* */
/* 03-01-1993 Created initial version 1.0 */
/* 04-19-1993 Verified version 1.0 */
/* 03-01-1994 Changed function interfaces to */
/* match those in prototype, */
/* added register options, changed */
/* protection logic to reduce */
/* overhead, resulting in */
/* version 1.1 */
/* */
/* 03-18-1994 Verified version 1.1 */
/* */
/*************************************************************************/
STATUS SMC_Obtain_Semaphore(NU_SEMAPHORE *semaphore_ptr, UNSIGNED suspend)
{
R1 SM_SCB *semaphore; /* Semaphore control blk ptr */
R2 SM_SUSPEND *suspend_ptr; /* Suspend block pointer */
SM_SUSPEND suspend_block; /* Allocate suspension block */
TC_TCB *task; /* Task pointer */
STATUS status; /* Completion status */
NU_SUPERV_USER_VARIABLES
/* Switch to supervisor mode */
NU_SUPERVISOR_MODE();
/* Move input semaphore pointer into internal pointer. */
semaphore = (SM_SCB *) semaphore_ptr;
#ifdef NU_ENABLE_STACK_CHECK
/* Call stack checking function to check for an overflow condition. */
TCT_Check_Stack();
#endif
#ifdef NU_ENABLE_HISTORY
/* Make an entry that corresponds to this function in the system history
log. */
HIC_Make_History_Entry(NU_OBTAIN_SEMAPHORE_ID, (UNSIGNED) semaphore,
(UNSIGNED) suspend, (UNSIGNED) 0);
#endif
/* Initialize the status as successful. */
status = NU_SUCCESS;
/* Protect against simultaneous access to the semaphore. */
TCT_System_Protect();
/* Determine if the semaphore has an instance (can be decremented). */
if (semaphore -> sm_semaphore_count)
{
/* Semaphore available. Decrement and return to the caller. */
semaphore -> sm_semaphore_count--;
#ifdef INCLUDE_PROVIEW
_RTProf_DumpSema(RT_PROF_OBTAIN_SEMAPHORE,semaphore, RT_PROF_OK);
#endif
}
else
{
/* Semaphore is not available. Determine if suspension is required. */
if (suspend)
{
/* Suspension is selected. */
/* Increment the number of tasks waiting. */
semaphore -> sm_tasks_waiting++;
#ifdef INCLUDE_PROVIEW
_RTProf_DumpSema(RT_PROF_OBTAIN_SEMAPHORE,semaphore , RT_PROF_WAIT);
#endif
/* Setup the suspend block and suspend the calling task. */
suspend_ptr = &suspend_block;
suspend_ptr -> sm_semaphore = semaphore;
suspend_ptr -> sm_suspend_link.cs_next = NU_NULL;
suspend_ptr -> sm_suspend_link.cs_previous = NU_NULL;
task = (TC_TCB *) TCT_Current_Thread();
suspend_ptr -> sm_suspended_task = task;
/* Determine if priority or FIFO suspension is associated with the
semaphore. */
if (semaphore -> sm_fifo_suspend)
{
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