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view src/nucleus/pis.c @ 243:35474f3a1782
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| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Mon, 03 May 2021 04:43:06 +0000 |
| parents | 4e78acac3d88 |
| children |
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/*************************************************************************/ /* */ /* Copyright Mentor Graphics Corporation 2002 */ /* All Rights Reserved. */ /* */ /* THIS WORK CONTAINS TRADE SECRET AND PROPRIETARY INFORMATION WHICH IS */ /* THE PROPERTY OF MENTOR GRAPHICS CORPORATION OR ITS LICENSORS AND IS */ /* SUBJECT TO LICENSE TERMS. */ /* */ /*************************************************************************/ /*************************************************************************/ /* */ /* FILE NAME VERSION */ /* */ /* pis.c Nucleus PLUS 1.14 */ /* */ /* COMPONENT */ /* */ /* PI - Pipe Management */ /* */ /* DESCRIPTION */ /* */ /* This file contains the supplemental routines for the pipe */ /* management component. */ /* */ /* DATA STRUCTURES */ /* */ /* None */ /* */ /* FUNCTIONS */ /* */ /* PIS_Reset_Pipe Reset a pipe */ /* PIS_Send_To_Front_Of_Pipe Send message to pipe's front */ /* PIS_Broadcast_To_Pipe Broadcast a message to pipe */ /* */ /* DEPENDENCIES */ /* */ /* cs_extr.h Common Service functions */ /* tc_extr.h Thread Control functions */ /* pi_extr.h Pipe functions */ /* hi_extr.h History functions */ /* */ /* HISTORY */ /* */ /* DATE REMARKS */ /* */ /* 03-01-1994 Created initial version 1.1 from */ /* routines originally in core */ /* */ /* 03-18-1994 Verified version 1.1 */ /* 04-17-1996 updated to version 1.2 */ /* 02-04-1998 Corrected SPR434 resulting in */ /* version 1.2a. */ /* 03-24-1998 Released version 1.3 */ /* 03-26-1999 Released 1.11m (new release */ /* numbering scheme) */ /* 04-17-2002 Released version 1.13m */ /* 11-07-2002 Released version 1.14 */ /*************************************************************************/ #define NU_SOURCE_FILE #include "cs_extr.h" /* Common service functions */ #include "tc_extr.h" /* Thread control functions */ #include "pi_extr.h" /* Pipe functions */ #include "hi_extr.h" /* History functions */ #include "profiler.h" /* ProView interface */ /* Define external inner-component global data references. */ extern CS_NODE *PID_Created_Pipes_List; extern UNSIGNED PID_Total_Pipes; extern TC_PROTECT PID_List_Protect; /* Define internal component function prototypes. */ VOID PIC_Cleanup(VOID *information); /*************************************************************************/ /* */ /* FUNCTION */ /* */ /* PIS_Reset_Pipe */ /* */ /* DESCRIPTION */ /* */ /* This function resets the specified pipe back to the original */ /* state. Any messages in the pipe are discarded. Also, any */ /* tasks currently suspended on the pipe are resumed with the */ /* reset status. */ /* */ /* CALLED BY */ /* */ /* Application */ /* PISE_Reset_Pipe Error checking shell */ /* */ /* CALLS */ /* */ /* [HIC_Make_History_Entry] Make entry in history log */ /* TCC_Resume_Task Resume a suspended task */ /* [TCT_Check_Stack] Stack checking function */ /* TCT_Control_To_System Transfer control to system */ /* TCT_System_Protect Protect against system access*/ /* TCT_Unprotect Release protection */ /* */ /* INPUTS */ /* */ /* pipe_ptr Pipe control block pointer */ /* */ /* OUTPUTS */ /* */ /* NU_SUCCESS */ /* */ /* HISTORY */ /* */ /* NAME 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, fixed read and write */ /* pointers to both point at the */ /* start, resulting in version 1.1 */ /* */ /* 03-18-1994 Verified version 1.1 */ /* 02-04-1998 Corrected SPR434. */ /* */ /*************************************************************************/ STATUS PIS_Reset_Pipe(NU_PIPE *pipe_ptr) { R1 PI_PCB *pipe; /* Pipe control block ptr */ PI_SUSPEND *suspend_ptr; /* Suspend block pointer */ PI_SUSPEND *next_ptr; /* Next suspend block pointer*/ STATUS preempt; /* Status for resume call */ NU_SUPERV_USER_VARIABLES /* Switch to supervisor mode */ NU_SUPERVISOR_MODE(); /* Move input pipe pointer into internal pointer. */ pipe = (PI_PCB *) pipe_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_RESET_PIPE_ID, (UNSIGNED) pipe, (UNSIGNED) 0, (UNSIGNED) 0); #endif /* Protect against access to the pipe. */ TCT_System_Protect(); /* Pickup the suspended task suspension list. */ suspend_ptr = pipe -> pi_suspension_list; /* Walk the chain task(s) currently suspended on the pipe. */ preempt = 0; while (suspend_ptr) { /* Resume the suspended task. Insure that the status returned is NU_PIPE_RESET. */ suspend_ptr -> pi_return_status = NU_PIPE_RESET; /* Point to the next suspend structure in the link. */ next_ptr = (PI_SUSPEND *) (suspend_ptr -> pi_suspend_link.cs_next); /* Resume the specified task. */ preempt = preempt | TCC_Resume_Task((NU_TASK *) suspend_ptr -> pi_suspended_task, NU_PIPE_SUSPEND); /* Determine if the next is the same as the head pointer. */ if (next_ptr == pipe -> pi_suspension_list) /* Clear the suspension pointer to signal the end of the list traversal. */ suspend_ptr = NU_NULL; else /* Position the suspend pointer to the next block. */ suspend_ptr = next_ptr; } /* Pickup the urgent message suspension list. */ suspend_ptr = pipe -> pi_urgent_list; /* Walk the chain task(s) currently suspended on the pipe. */ while (suspend_ptr) { /* Resume the suspended task. Insure that the status returned is NU_PIPE_RESET. */ suspend_ptr -> pi_return_status = NU_PIPE_RESET; /* Point to the next suspend structure in the link. */ next_ptr = (PI_SUSPEND *) (suspend_ptr -> pi_suspend_link.cs_next); /* Resume the specified task. */ preempt = preempt | TCC_Resume_Task((NU_TASK *) suspend_ptr -> pi_suspended_task, NU_PIPE_SUSPEND); /* Determine if the next is the same as the head pointer. */ if (next_ptr == pipe -> pi_urgent_list) /* Clear the suspension pointer to signal the end of the list traversal. */ suspend_ptr = NU_NULL; else /* Position the suspend pointer to the next active block. */ suspend_ptr = next_ptr; } /* Initialize various elements of the pipe. */ pipe -> pi_available = pipe -> pi_end - pipe -> pi_start; pipe -> pi_messages = 0; pipe -> pi_read = pipe -> pi_start; pipe -> pi_write = pipe -> pi_start; pipe -> pi_tasks_waiting = 0; pipe -> pi_suspension_list = NU_NULL; pipe -> pi_urgent_list = NU_NULL; #ifdef INCLUDE_PROVIEW _RTProf_DumpPipe(RT_PROF_RESET_PIPE,pipe,RT_PROF_OK); #endif /* INCLUDE_PROVIEW */ /* 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 pipe. */ TCT_Unprotect(); /* Return to user mode */ NU_USER_MODE(); /* Return a successful completion. */ return(NU_SUCCESS); } /*************************************************************************/ /* */ /* FUNCTION */ /* */ /* PIS_Send_To_Front_Of_Pipe */ /* */ /* DESCRIPTION */ /* */ /* This function sends a message to the front of the specified */ /* message pipe. The message length is determined by the caller. */ /* If there are any tasks suspended on the pipe for a message, the */ /* message is copied into the message area of the first waiting */ /* task and that task is resumed. If there is enough room in the */ /* pipe, the message is copied in front of all other messages. */ /* If there is not enough room in the pipe, suspension of the */ /* caller is possible. */ /* */ /* CALLED BY */ /* */ /* Application */ /* PISE_Send_To_Front_Of_Pipe Error checking shell */ /* */ /* CALLS */ /* */ /* CSC_Place_On_List Place on suspend 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 */ /* [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 pipe */ /* TCT_Unprotect Release protection */ /* */ /* INPUTS */ /* */ /* pipe_ptr Pipe 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_PIPE_FULL If pipe is currently full */ /* NU_TIMEOUT If timeout on service expires*/ /* NU_PIPE_DELETED If pipe was deleted during */ /* suspension */ /* NU_PIPE_RESET If pipe was 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, optimized copy loop, */ /* resulting in version 1.1 */ /* */ /* 03-18-1994 Verified version 1.1 */ /* */ /*************************************************************************/ STATUS PIS_Send_To_Front_Of_Pipe(NU_PIPE *pipe_ptr, VOID *message, UNSIGNED size, UNSIGNED suspend) { R1 PI_PCB *pipe; /* Pipe control block ptr */ PI_SUSPEND suspend_block; /* Allocate suspension block */ PI_SUSPEND *suspend_ptr; /* Pointer to suspend block */ R2 BYTE_PTR source; /* Pointer to source */ R3 BYTE_PTR destination; /* Pointer to destination */ UNSIGNED copy_size; /* Partial copy size */ R4 INT i; /* Working counter */ UNSIGNED pad = 0; /* Number of pad bytes */ TC_TCB *task; /* Task pointer */ STATUS preempt; /* Preempt flag */ STATUS status; /* Completion status */ NU_SUPERV_USER_VARIABLES /* Switch to supervisor mode */ NU_SUPERVISOR_MODE(); /* Move input pipe pointer into internal pointer. */ pipe = (PI_PCB *) pipe_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_SEND_TO_FRONT_OF_PIPE_ID, (UNSIGNED) pipe, (UNSIGNED) message, (UNSIGNED) size); #endif /* Initialize the status as successful. */ status = NU_SUCCESS; /* Protect against simultaneous access to the pipe. */ TCT_System_Protect(); /* Determine if an extra word of overhead needs to be added to the calculation. */ if (pipe -> pi_fixed_size) /* No overhead. */ i = 0; else { /* Variable messages have one additional word of overhead. */ i = sizeof(UNSIGNED); /* Calculate the number of pad bytes necessary to keep the pipe write pointer on an UNSIGNED data element alignment. */ pad = (((size + sizeof(UNSIGNED) - 1)/sizeof(UNSIGNED)) * sizeof(UNSIGNED)) - size; /* Insure that padding is included in the overhead. */ i = i + ((INT) pad); /* Make special check to see if a suspension needs to be forced for a variable length message. */ if ((pipe -> pi_suspension_list) && (pipe -> pi_messages)) { /* Pickup task control block pointer. */ task = (TC_TCB *) TCT_Current_Thread(); /* 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 ((pipe -> pi_fifo_suspend) || (suspend == NU_NO_SUSPEND) || ((pipe -> pi_suspension_list) -> pi_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) pipe -> pi_available; } } /* Determine if there is enough room in the pipe for the message. */ if (pipe -> pi_available < (size + i)) { /* pipe does not have room for the message. Determine if suspension is required. */ if (suspend) { /* Suspension is requested. */ /* Increment the number of tasks waiting. */ pipe -> pi_tasks_waiting++; #ifdef INCLUDE_PROVIEW _RTProf_DumpPipe(RT_PROF_SEND_TO_FRONT_OF_PIPE,pipe,RT_PROF_WAIT); #endif /* INCLUDE_PROVIEW */ /* Setup the suspend block and suspend the calling task. */ suspend_ptr = &suspend_block; suspend_ptr -> pi_pipe = pipe; suspend_ptr -> pi_suspend_link.cs_next = NU_NULL; suspend_ptr -> pi_suspend_link.cs_previous = NU_NULL; suspend_ptr -> pi_message_area = (BYTE_PTR) message; suspend_ptr -> pi_message_size = size; task = (TC_TCB *) TCT_Current_Thread(); suspend_ptr -> pi_suspended_task = task; /* Place the task on the urgent message suspension list. */ CSC_Place_On_List((CS_NODE **) &(pipe -> pi_urgent_list), &(suspend_ptr -> pi_suspend_link)); /* Move the head pointer of the list to make this suspension the first in the list. */ pipe -> pi_urgent_list = (PI_SUSPEND *) (pipe -> pi_urgent_list) -> pi_suspend_link.cs_previous; /* Finally, suspend the calling task. Note that the suspension call automatically clears the protection on the pipe. */ TCC_Suspend_Task((NU_TASK *) task, NU_PIPE_SUSPEND, PIC_Cleanup, suspend_ptr, suspend); /* Pickup the return status. */ status = suspend_ptr -> pi_return_status; } else { /* Return a status of NU_PIPE_FULL because there is no room in the pipe for the message. */ status = NU_PIPE_FULL; #ifdef INCLUDE_PROVIEW _RTProf_DumpPipe(RT_PROF_SEND_TO_FRONT_OF_PIPE,pipe,RT_PROF_FAIL); #endif /* INCLUDE_PROVIEW */ } } else { /* Determine if a task is waiting on an empty pipe. */ if ((pipe -> pi_suspension_list) && (pipe -> pi_messages == 0)) { /* Task is waiting on pipe for a message. */ /* Decrement the number of tasks waiting on pipe. */ pipe -> pi_tasks_waiting--; #ifdef INCLUDE_PROVIEW _RTProf_DumpPipe(RT_PROF_SEND_TO_FRONT_OF_PIPE,pipe,RT_PROF_OK); #endif /* INCLUDE_PROVIEW */ /* Remove the first suspended block from the list. */ suspend_ptr = pipe -> pi_suspension_list; CSC_Remove_From_List((CS_NODE **) &(pipe -> pi_suspension_list), &(suspend_ptr -> pi_suspend_link)); /* Setup the source and destination pointers. */ source = (BYTE_PTR) message; destination = suspend_ptr -> pi_message_area; /* Initialize the return status. */ suspend_ptr -> pi_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 -> pi_actual_size = size; /* Wakeup the waiting task and check for preemption. */ preempt = TCC_Resume_Task((NU_TASK *) suspend_ptr -> pi_suspended_task, NU_PIPE_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 pipe and no task is waiting. */ /* Setup the source pointer. */ source = (BYTE_PTR) message; destination = pipe -> pi_read; /* Process according to the type of message supported. */ if (pipe -> pi_fixed_size) { /* Fixed-size message pipe. */ /* Determine if the read pointer is at the top of the pipe area. */ if (destination == pipe -> pi_start) /* Prepare to place the message in the lower part of the pipe area. */ destination = pipe -> pi_end - size; else /* Backup the length of the message from the current read pointer. */ destination = destination - size; /* Adjust the actual read pointer before the copy is done. */ pipe -> pi_read = destination; /* Copy the message into the pipe area. */ i = (INT) size; do { *(destination++) = *(source); if ((--i) == 0) break; source++; } while (1); } else { /* Variable-length message pipe. */ /* Calculate the number of bytes remaining from the write pointer to the bottom of the pipe. */ copy_size = destination - pipe -> pi_start; /* Determine if part of the message needs to be placed at the bottom of the pipe area. */ if (copy_size < (size + i)) /* Compute the starting location for the message. */ destination = pipe -> pi_end - ((size + i) - copy_size); else /* Compute the starting location for the message. */ destination = destination - (size + i); /* Adjust the actual pipe read pointer also. */ pipe -> pi_read = destination; /* Place message size in first location. */ *((UNSIGNED *) destination) = size; destination = destination + sizeof(UNSIGNED); /* Check for a wrap-around condition on the pipe. */ if (destination >= pipe -> pi_end) /* Wrap the write pointer back to the top of the pipe area. */ destination = pipe -> pi_start; /* Decrement the number of bytes remaining for this extra word of overhead. */ pipe -> pi_available = pipe -> pi_available - sizeof(UNSIGNED); /* Calculate the number of bytes remaining from the write pointer to the bottom of the pipe. */ copy_size = pipe -> pi_end - destination; /* Determine if the message needs to be wrapped around the edge of the pipe area. */ if (copy_size >= (size + pad)) { /* 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 = pipe -> pi_start; /* Determine if there is anything left to copy. */ if (size > copy_size) { /* Yes, there is something to copy. */ i = (INT) (size - copy_size); do { *(destination++) = *(source); if ((--i) == 0) break; source++; } while (1); } } /* Decrement the number of available bytes. */ pipe -> pi_available = pipe -> pi_available - pad; } /* Decrement the number of available bytes. */ pipe -> pi_available = pipe -> pi_available - size; /* Increment the number of messages in the pipe. */ pipe -> pi_messages++; #ifdef INCLUDE_PROVIEW _RTProf_DumpPipe(RT_PROF_SEND_TO_FRONT_OF_PIPE,pipe,RT_PROF_OK); #endif /* INCLUDE_PROVIEW */ } } /* Release protection against access to the pipe. */ TCT_Unprotect(); /* Return to user mode */ NU_USER_MODE(); /* Return the completion status. */ return(status); } /*************************************************************************/ /* */ /* FUNCTION */ /* */ /* PIS_Broadcast_To_Pipe */ /* */ /* DESCRIPTION */ /* */ /* This function sends a message to all tasks waiting for a message */ /* from the specified pipe. If there are no tasks waiting for a */ /* message the service performs like a standard send request. */ /* */ /* CALLED BY */ /* */ /* Application */ /* PISE_Broadcast_To_Pipe 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 pipe */ /* TCT_Unprotect Release protection */ /* */ /* INPUTS */ /* */ /* pipe_ptr Pipe 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_PIPE_FULL If pipe is currently full */ /* NU_TIMEOUT If timeout on service expires*/ /* NU_PIPE_DELETED If pipe was deleted during */ /* suspension */ /* NU_PIPE_RESET If pipe was 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, optimized copy loop, */ /* resulting in version 1.1 */ /* */ /* 03-18-1994 Verified version 1.1 */ /* */ /*************************************************************************/ STATUS PIS_Broadcast_To_Pipe(NU_PIPE *pipe_ptr, VOID *message, UNSIGNED size, UNSIGNED suspend) { R1 PI_PCB *pipe; /* Pipe control block ptr */ PI_SUSPEND suspend_block; /* Allocate suspension block */ PI_SUSPEND *suspend_ptr; /* Pointer to suspend block */ R2 BYTE_PTR source; /* Pointer to source */ R3 BYTE_PTR destination; /* Pointer to destination */ UNSIGNED copy_size; /* Partial copy size */ UNSIGNED pad = 0; /* Number of pad bytes */ R4 INT i; /* Working counter */ TC_TCB *task; /* Task pointer */ STATUS preempt; /* Preempt flag */ STATUS status; /* Completion status */ NU_SUPERV_USER_VARIABLES /* Switch to supervisor mode */ NU_SUPERVISOR_MODE(); /* Move input pipe pointer into internal pointer. */ pipe = (PI_PCB *) pipe_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_BROADCAST_TO_PIPE_ID, (UNSIGNED) pipe, (UNSIGNED) message, (UNSIGNED) size); #endif /* Initialize the status as successful. */ status = NU_SUCCESS; /* Protect against simultaneous access to the pipe. */ TCT_System_Protect(); /* Determine if an extra word of overhead needs to be added to the calculation. */ if (pipe -> pi_fixed_size) /* No overhead. */ i = 0; else { /* Variable messages have one additional word of overhead. */ i = sizeof(UNSIGNED); /* Calculate the number of pad bytes necessary to keep the pipe write pointer on an UNSIGNED data element alignment. */ pad = (((size + sizeof(UNSIGNED) - 1)/sizeof(UNSIGNED)) * sizeof(UNSIGNED)) - size; /* Insure that padding is included in the overhead. */ i = i + ((INT) pad); /* Make special check to see if a suspension needs to be forced for a variable length message. */ if ((pipe -> pi_suspension_list) && (pipe -> pi_messages)) { /* Pickup task control block pointer. */ task = (TC_TCB *) TCT_Current_Thread(); /* 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 ((pipe -> pi_fifo_suspend) || (suspend == NU_NO_SUSPEND) || ((pipe -> pi_suspension_list) -> pi_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) pipe -> pi_available; } } /* Determine if there is enough room in the pipe for the message. */ if (pipe -> pi_available < (size + i)) { /* pipe does not have room for the message. Determine if suspension is required. */ if (suspend) { /* Suspension is requested. */ /* Increment the number of tasks waiting. */ pipe -> pi_tasks_waiting++; #ifdef INCLUDE_PROVIEW _RTProf_DumpPipe(RT_PROF_BROADCAST_TO_PIPE,pipe,RT_PROF_WAIT); #endif /* INCLUDE_PROVIEW */ /* Setup the suspend block and suspend the calling task. */ suspend_ptr = &suspend_block; suspend_ptr -> pi_pipe = pipe; suspend_ptr -> pi_suspend_link.cs_next = NU_NULL; suspend_ptr -> pi_suspend_link.cs_previous = NU_NULL; suspend_ptr -> pi_message_area = (BYTE_PTR) message; suspend_ptr -> pi_message_size = size; task = (TC_TCB *) TCT_Current_Thread(); suspend_ptr -> pi_suspended_task = task; /* Determine if priority or FIFO suspension is associated with the pipe. */ if (pipe -> pi_fifo_suspend) { /* FIFO suspension is required. Link the suspend block into the list of suspended tasks on this pipe. */ CSC_Place_On_List((CS_NODE **) &(pipe -> pi_suspension_list), &(suspend_ptr -> pi_suspend_link)); } else { /* Get the priority of the current thread so the suspend block can be placed in the appropriate place. */ suspend_ptr -> pi_suspend_link.cs_priority = TCC_Task_Priority(task); CSC_Priority_Place_On_List((CS_NODE **) &(pipe -> pi_suspension_list), &(suspend_ptr -> pi_suspend_link)); } /* Finally, suspend the calling task. Note that the suspension call automatically clears the protection on the pipe. */ TCC_Suspend_Task((NU_TASK *) task, NU_PIPE_SUSPEND, PIC_Cleanup, suspend_ptr, suspend); /* Pickup the return status. */ status = suspend_ptr -> pi_return_status; } else { /* Return a status of NU_PIPE_FULL because there is no room in the pipe for the message. */ status = NU_PIPE_FULL; #ifdef INCLUDE_PROVIEW _RTProf_DumpPipe(RT_PROF_BROADCAST_TO_PIPE,pipe,RT_PROF_FAIL); #endif /* INCLUDE_PROVIEW */ } } else { #ifdef INCLUDE_PROVIEW _RTProf_DumpPipe(RT_PROF_BROADCAST_TO_PIPE,pipe,RT_PROF_OK); #endif /* INCLUDE_PROVIEW */ /* Determine if a task is waiting on an empty pipe. */ if ((pipe -> pi_suspension_list) && (pipe -> pi_messages == 0)) { /* Yes, one or more tasks are waiting for a message from this pipe. */ preempt = 0; do { /* Decrement the number of tasks waiting on pipe. */ pipe -> pi_tasks_waiting--; /* Remove the first suspended block from the list. */ suspend_ptr = pipe -> pi_suspension_list; CSC_Remove_From_List((CS_NODE **) &(pipe -> pi_suspension_list), &(suspend_ptr -> pi_suspend_link)); /* Setup the source and destination pointers. */ source = (BYTE_PTR) message; destination = suspend_ptr -> pi_message_area; /* Initialize the return status. */ suspend_ptr -> pi_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 -> pi_actual_size = size; /* Wakeup the waiting task and check for preemption. */ preempt = preempt | TCC_Resume_Task((NU_TASK *) suspend_ptr -> pi_suspended_task, NU_PIPE_SUSPEND); /* Move the suspend pointer to the next node, which is now at the head of the list. */ suspend_ptr = pipe -> pi_suspension_list; } while (suspend_ptr); /* 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 pipe and no task is waiting. */ /* Setup the source pointer. */ source = (BYTE_PTR) message; destination = pipe -> pi_write; /* Process according to the type of message supported. */ if (pipe -> pi_fixed_size) { /* Fixed-size messages are supported by this pipe. */ /* Loop to copy the message into the pipe area. */ i = (INT) size; do { *(destination++) = *(source); if ((--i) == 0) break; source++; } while (1); } else { /* Variable-size messages are supported. Processing must check for pipe wrap-around conditions. */ /* Place message size in first location. */ *((UNSIGNED *) destination) = size; destination = destination + sizeof(UNSIGNED); /* Check for a wrap-around condition on the pipe. */ if (destination >= pipe -> pi_end) /* Wrap the write pointer back to the top of the pipe area. */ destination = pipe -> pi_start; /* Decrement the number of bytes remaining for this extra word of overhead. */ pipe -> pi_available = pipe -> pi_available - sizeof(UNSIGNED); /* Calculate the number of bytes remaining from the write pointer to the bottom of the pipe. */ copy_size = pipe -> pi_end - destination; /* Determine if the message needs to be wrapped around the edge of the pipe 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 = pipe -> pi_start; i = (INT) (size - copy_size); do { *(destination++) = *(source); if ((--i) == 0) break; source++; } while (1); } } /* Check again for wrap-around condition on the write pointer. */ if (destination >= pipe -> pi_end) /* Move the write pointer to the top of the pipe area. */ destination = pipe -> pi_start; /* Determine if the pipe supports variable-length messages. If so, pad bytes are needed to keep UNSIGNED alignment. */ if (pad) { /* Variable-size message. Add pad bytes to the write pointer. */ /* Calculate the number of bytes remaining from the write pointer to the bottom of the pipe. */ copy_size = pipe -> pi_end - destination; /* If there is not enough room at the bottom of the pipe, the pad bytes must be wrapped around to the top. */ if (copy_size <= pad) /* Move write pointer to the top of the pipe and make the necessary adjustment. */ destination = pipe -> pi_start + (pad - copy_size); else /* There is enough room in the pipe to simply add the the pad bytes to the write pointer. */ destination = destination + pad; /* Decrement the number of available bytes. */ pipe -> pi_available = pipe -> pi_available - pad; } /* Update the actual write pointer. */ pipe -> pi_write = destination; /* Decrement the number of available bytes. */ pipe -> pi_available = pipe -> pi_available - size; /* Increment the number of messages in the pipe. */ pipe -> pi_messages++; } } /* Release protection against access to the pipe. */ TCT_Unprotect(); /* Return to user mode */ NU_USER_MODE(); /* Return the completion status. */ return(status); }