qus.c
来自「nucleus 2006 source code」· C语言 代码 · 共 1,017 行 · 第 1/3 页
C
1,017 行
/* Now we know that there are other task(s) are suspended trying
to send a variable length message. Determine whether or not
a suspension should be forced. */
if ((queue -> qu_fifo_suspend) ||
(suspend == NU_NO_SUSPEND) ||
((queue -> qu_suspension_list) -> qu_suspend_link.cs_priority <=
TCC_Task_Priority(task)))
/* Bump the computed size to avoid placing the new variable
length message ahead of the suspended tasks. */
i = (INT) queue -> qu_available;
}
}
/* Determine if there is enough room in the queue for the message. */
if (queue -> qu_available < (size + i))
{
/* Queue does not have room for the message. Determine if
suspension is required. */
if (suspend)
{
/* Suspension is requested. */
/* Increment the number of tasks waiting. */
queue -> qu_tasks_waiting++;
#ifdef NU_PROFILE_PLUS
PRF_PLUS_QUS_SEND_TO_FRONT_OF_QUEUE_0
#endif /* NU_PROFILE_PLUS */
/* Setup the suspend block and suspend the calling task. */
suspend_ptr = &suspend_block;
suspend_ptr -> qu_queue = queue;
suspend_ptr -> qu_suspend_link.cs_next = NU_NULL;
suspend_ptr -> qu_suspend_link.cs_previous = NU_NULL;
suspend_ptr -> qu_message_area = (UNSIGNED_PTR) message;
suspend_ptr -> qu_message_size = size;
task = (TC_TCB *) TCT_Current_Thread();
suspend_ptr -> qu_suspended_task = task;
/* Place the task on the urgent message suspension list. */
CSC_Place_On_List((CS_NODE **) &(queue -> qu_urgent_list),
&(suspend_ptr -> qu_suspend_link));
/* Move the head pointer of the list to make this suspension the
first in the list. */
queue -> qu_urgent_list = (QU_SUSPEND *)
(queue -> qu_urgent_list) -> qu_suspend_link.cs_previous;
/* Finally, suspend the calling task. Note that the suspension call
automatically clears the protection on the queue. */
TCC_Suspend_Task((NU_TASK *) task, NU_QUEUE_SUSPEND,
QUC_Cleanup, suspend_ptr, suspend);
/* Pickup the return status. */
status = suspend_ptr -> qu_return_status;
}
else
{
/* Return a status of NU_QUEUE_FULL because there is no
room in the queue for the message. */
status = NU_QUEUE_FULL;
#ifdef NU_PROFILE_PLUS
PRF_PLUS_QUS_SEND_TO_FRONT_OF_QUEUE_1
#endif /* NU_PROFILE_PLUS */
}
}
else
{
/* Determine if a task is waiting on an empty queue. */
if ((queue -> qu_suspension_list) && (queue -> qu_messages == 0))
{
/* Task is waiting on queue for a message. */
/* Decrement the number of tasks waiting on queue. */
queue -> qu_tasks_waiting--;
#ifdef NU_PROFILE_PLUS
PRF_PLUS_QUS_SEND_TO_FRONT_OF_QUEUE_2
#endif /* NU_PROFILE_PLUS */
/* Remove the first suspended block from the list. */
suspend_ptr = queue -> qu_suspension_list;
CSC_Remove_From_List((CS_NODE **) &(queue -> qu_suspension_list),
&(suspend_ptr -> qu_suspend_link));
/* Setup the source and destination pointers. */
source = (UNSIGNED_PTR) message;
destination = suspend_ptr -> qu_message_area;
/* Initialize the return status. */
suspend_ptr -> qu_return_status = NU_SUCCESS;
/* Loop to actually copy the message. */
i = (INT) size;
do
{
*(destination++) = *(source);
if ((--i) == 0)
break;
source++;
} while (1);
/* Return the size of the message copied. */
suspend_ptr -> qu_actual_size = size;
/* Wakeup the waiting task and check for preemption. */
preempt =
TCC_Resume_Task((NU_TASK *) suspend_ptr -> qu_suspended_task,
NU_QUEUE_SUSPEND);
/* Determine if preemption needs to take place. */
if (preempt)
/* Transfer control to the system if the resumed task function
detects a preemption condition. */
TCT_Control_To_System();
}
else
{
/* There is enough room in the queue and no task is waiting. */
/* Setup the source pointer. */
source = (UNSIGNED_PTR) message;
destination = queue -> qu_read;
/* Process according to the type of message supported. */
if (queue -> qu_fixed_size)
{
/* Fixed-size message queue. */
/* Determine if the read pointer is at the top of the queue
area. */
if (destination == queue -> qu_start)
/* Prepare to place the message in the lower part
of the queue area. */
destination = queue -> qu_end - size;
else
/* Backup the length of a message from the current
read pointer. */
destination = destination - size;
/* Adjust the actual read pointer before the copy is done. */
queue -> qu_read = destination;
/* Copy the message into the queue area. */
i = (INT) size;
do
{
*(destination++) = *(source);
if ((--i) == 0)
break;
source++;
} while (1);
}
else
{
/* Variable-size message queue. */
/* Calculate the number of words remaining at the top of the
queue. */
copy_size = destination - queue -> qu_start;
/* Determine if part of the message needs to be placed at the
bottom of the queue area. */
if (copy_size < (size + i))
/* Compute the starting location for the message. */
destination = queue -> qu_end - ((size +i) - copy_size);
else
/* Compute the starting location for the message. */
destination = destination - (size + i);
/* Adjust the actual queue read pointer also. */
queue -> qu_read = destination;
/* Place message size in first location. */
*(destination++) = size;
/* Check for a wrap-around condition on the queue. */
if (destination >= queue -> qu_end)
/* Wrap the write pointer back to the top of the queue
area. */
destination = queue -> qu_start;
/* Decrement the number of words remaining by 1 for this
extra word of overhead. */
queue -> qu_available--;
/* Calculate the number of words remaining from the
destination pointer to the bottom of the queue. */
copy_size = queue -> qu_end - destination;
/* Determine if the message needs to be wrapped around the
edge of the queue area. */
if (copy_size >= size)
{
/* Copy the whole message at once. */
i = (INT) size;
do
{
*(destination++) = *(source);
if ((--i) == 0)
break;
source++;
} while (1);
}
else
{
/* Copy the first half of the message. */
i = (INT) copy_size;
do
{
*(destination) = *(source++);
if ((--i) == 0)
break;
destination++;
} while (1);
/* Copy the second half of the message. */
destination = queue -> qu_start;
i = (INT) (size - copy_size);
do
{
*(destination++) = *(source);
if ((--i) == 0)
break;
source++;
} while (1);
}
}
/* Decrement the number of available words. */
queue -> qu_available = queue -> qu_available - size;
/* Increment the number of messages in the queue. */
queue -> qu_messages++;
#ifdef NU_PROFILE_PLUS
PRF_PLUS_QUS_SEND_TO_FRONT_OF_QUEUE_3
#endif /* NU_PROFILE_PLUS */
}
}
/* Release protection against access to the queue. */
TCT_Unprotect();
/* Return to user mode */
NU_USER_MODE();
/* Return the completion status. */
return(status);
}
/*************************************************************************/
/* */
/* FUNCTION */
/* */
/* QUS_Broadcast_To_Queue */
/* */
/* DESCRIPTION */
/* */
/* This function sends a message to all tasks waiting for a message */
/* from the specified queue. If there are no tasks waiting for a */
/* message the service performs like a standard send request. */
/* */
/* CALLED BY */
/* */
/* Application */
/* QUSE_Broadcast_To_Queue Error checking shell */
/* */
/* CALLS */
/* */
/* CSC_Place_On_List Place on suspend list */
/* CSC_Priority_Place_On_List Place on priority list */
/* CSC_Remove_From_List Remove from suspend list */
/* [HIC_Make_History_Entry] Make entry in history log */
/* TCC_Resume_Task Resume a suspended task */
/* TCC_Suspend_Task Suspend calling task */
/* TCC_Task_Priority Pickup task's priority */
/* [TCT_Check_Stack] Stack checking function */
/* TCT_Control_To_System Transfer control to system */
/* TCT_Current_Thread Pickup current thread pointer*/
/* TCT_System_Protect Protect queue */
/* TCT_Unprotect Release protection */
/* */
/* INPUTS */
/* */
/* queue_ptr Queue control block pointer */
/* message Pointer to message to send */
/* size Size of message to send */
/* suspend Suspension option if full */
/* */
/* OUTPUTS */
/* */
/* NU_SUCCESS If service is successful */
/* NU_QUEUE_FULL If queue is currently full */
/* NU_TIMEOUT If timeout on service expires*/
/* NU_QUEUE_DELETED If queue was deleted during */
/* suspension */
/* NU_QUEUE_RESET If queue was reset during */
/* suspension */
/* */
/*************************************************************************/
STATUS QUS_Broadcast_To_Queue(NU_QUEUE *queue_ptr, VOID *message,
UNSIGNED size, UNSIGNED suspend)
{
R1 QU_QCB *queue; /* Queue control block ptr */
QU_SUSPEND suspend_block; /* Allocate suspension block */
QU_SUSPEND *suspend_ptr; /* Pointer to suspend block */
R3 UNSIGNED_PTR source; /* Pointer to source */
R4 UNSIGNED_PTR destination; /* Pointer to destination */
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