diff nuc-fw/nucleus/pic.c @ 79:947b1f473960

beginning of nuc-fw
author Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
date Sun, 11 Aug 2013 07:17:25 +0000
parents
children
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nuc-fw/nucleus/pic.c	Sun Aug 11 07:17:25 2013 +0000
@@ -0,0 +1,1617 @@
+/*************************************************************************/
+/*                                                                       */
+/*               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       */
+/*                                                                       */
+/*      pic.c                                          Nucleus PLUS 1.14 */
+/*                                                                       */
+/* COMPONENT                                                             */
+/*                                                                       */
+/*      PI - Pipe Management                                             */
+/*                                                                       */
+/* DESCRIPTION                                                           */
+/*                                                                       */
+/*      This file contains the core routines for the pipe management     */
+/*      component.                                                       */
+/*                                                                       */
+/* DATA STRUCTURES                                                       */
+/*                                                                       */
+/*      None                                                             */
+/*                                                                       */
+/* FUNCTIONS                                                             */
+/*                                                                       */
+/*      PIC_Create_Pipe                     Create a message pipe        */
+/*      PIC_Delete_Pipe                     Delete a message pipe        */
+/*      PIC_Send_To_Pipe                    Send message to a pipe       */
+/*      PIC_Receive_From_Pipe               Receive a message from pipe  */
+/*      PIC_Cleanup                         Cleanup on timeout or a      */
+/*                                            terminate condition        */
+/*                                                                       */
+/* 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                              */
+/*                                                                       */
+/*      03-01-1993      Created initial version 1.0                      */
+/*      04-19-1993      Verified version 1.0                             */
+/*      08-09-1993      Corrected pointer retrieval                      */
+/*                      loop, resulting in version 1.0a                  */
+/*      08-09-1993      Verified version 1.0a                            */
+/*      03-01-1994      Moved non-core functions into                    */
+/*                      supplemental files, changed                      */
+/*                      function interfaces to match                     */
+/*                      those in prototype, added                        */
+/*                      register options, changed                        */
+/*                      protection logic to reduce                       */
+/*                      overhead, corrected bug in                       */
+/*                      pipe reset, optimized item                       */
+/*                      copy loops, resulting in                         */
+/*                      version 1.1                                      */
+/*                                                                       */
+/*      03-18-1994      Verified version 1.1                             */
+/*      04-17-1996      updated to version 1.2                           */
+/*      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                                                              */
+/*                                                                       */
+/*      PIC_Create_Pipe                                                  */
+/*                                                                       */
+/* DESCRIPTION                                                           */
+/*                                                                       */
+/*      This function creates a pipe and then places it on the list      */
+/*      of created pipes.                                                */
+/*                                                                       */
+/* CALLED BY                                                             */
+/*                                                                       */
+/*      Application                                                      */
+/*      PICE_Create_Pipe                    Error checking shell         */
+/*                                                                       */
+/* CALLS                                                                 */
+/*                                                                       */
+/*      CSC_Place_On_List                   Add to node to linked-list   */
+/*      [HIC_Make_History_Entry]            Make entry in history log    */
+/*      [TCT_Check_Stack]                   Stack checking function      */
+/*      TCT_Protect                         Data structure protect       */
+/*      TCT_Unprotect                       Un-protect data structure    */
+/*                                                                       */
+/* INPUTS                                                                */
+/*                                                                       */
+/*      pipe_ptr                            Pipe control block pointer   */
+/*      name                                Pipe name                    */
+/*      start_address                       Starting address of actual   */
+/*                                            pipe area                  */
+/*      pipe_size                           Total size of pipe in bytes  */
+/*      message_type                        Type of message supported by */
+/*                                            the pipe (fixed/variable)  */
+/*      message_size                        Size of message.  Variable   */
+/*                                            message-length pipes, this */
+/*                                            represents the maximum size*/
+/*      suspend_type                        Suspension type              */
+/*                                                                       */
+/* OUTPUTS                                                               */
+/*                                                                       */
+/*      NU_SUCCESS                                                       */
+/*                                                                       */
+/* 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,                          */
+/*                      resulting in version 1.1                         */
+/*                                                                       */
+/*      03-18-1994      Verified version 1.1                             */
+/*                                                                       */
+/*************************************************************************/
+STATUS  PIC_Create_Pipe(NU_PIPE *pipe_ptr, CHAR *name,
+                      VOID *start_address, UNSIGNED pipe_size,
+                      OPTION message_type, UNSIGNED message_size,
+                      OPTION suspend_type)
+{
+
+R1 PI_PCB      *pipe;                       /* Pipe control block ptr    */
+INT             i;                          /* Working index variable    */
+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_CREATE_PIPE_ID, (UNSIGNED) pipe,
+                                (UNSIGNED) name, (UNSIGNED) start_address);
+
+#endif
+
+    /* First, clear the pipe ID just in case it is an old pipe
+       Control Block.  */
+    pipe -> pi_id =             0;
+
+    /* Fill in the pipe name.  */
+    for (i = 0; i < NU_MAX_NAME; i++)
+        pipe -> pi_name[i] =  name[i];
+
+    /* Setup the pipe suspension type.  */
+    if (suspend_type == NU_FIFO)
+
+        /* FIFO suspension is selected, setup the flag accordingly.  */
+        pipe -> pi_fifo_suspend =  NU_TRUE;
+
+    else
+
+        /* Priority suspension is selected.  */
+        pipe -> pi_fifo_suspend =  NU_FALSE;
+
+    /* Setup the pipe message type.  */
+    if (message_type == NU_FIXED_SIZE)
+
+        /* Fixed-size messages are required.  */
+        pipe -> pi_fixed_size =  NU_TRUE;
+    else
+
+        /* Variable-size messages are required.  */
+        pipe -> pi_fixed_size =  NU_FALSE;
+
+    /* Setup the message size.  */
+    pipe -> pi_message_size =  message_size;
+
+    /* Clear the messages counter.   */
+    pipe -> pi_messages =  0;
+
+    /* Setup the actual pipe pointers.  */
+    pipe -> pi_pipe_size =     pipe_size;
+
+    /* Determine if the pipe's size needs to be adjusted.  */
+    if (pipe -> pi_fixed_size)
+
+        /* The size of a fixed-size message pipe must be an even multiple of
+           the actual message size.  */
+        pipe_size =  (pipe_size/message_size) * message_size;
+
+    else
+
+        /* Insure that the size is in terms of UNSIGNED data elements.  This
+           insures that the UNSIGNED word is never written past the end of
+           the pipe.  */
+        pipe_size =  (pipe_size/sizeof(UNSIGNED)) * sizeof(UNSIGNED);
+
+    pipe -> pi_available =     pipe_size;
+    pipe -> pi_start =         (BYTE_PTR) start_address;
+    pipe -> pi_end =           pipe -> pi_start + pipe_size;
+    pipe -> pi_read =          (BYTE_PTR) start_address;
+    pipe -> pi_write =         (BYTE_PTR) start_address;
+
+    /* Clear the suspension list pointer.  */
+    pipe -> pi_suspension_list =  NU_NULL;
+
+    /* Clear the number of tasks waiting on the pipe counter.  */
+    pipe -> pi_tasks_waiting =  0;
+
+    /* Clear the urgent message list pointer.  */
+    pipe -> pi_urgent_list =  NU_NULL;
+
+    /* Initialize link pointers.  */
+    pipe -> pi_created.cs_previous =    NU_NULL;
+    pipe -> pi_created.cs_next =        NU_NULL;
+
+    /* Protect against access to the list of created pipes.  */
+    TCT_Protect(&PID_List_Protect);
+
+    /* At this point the pipe is completely built.  The ID can now be
+       set and it can be linked into the created pipe list.  */
+    pipe -> pi_id =                     PI_PIPE_ID;
+
+    /* Link the pipe into the list of created pipes and increment the
+       total number of pipes in the system.  */
+    CSC_Place_On_List(&PID_Created_Pipes_List, &(pipe -> pi_created));
+    PID_Total_Pipes++;
+
+#ifdef INCLUDE_PROVIEW
+    _RTProf_DumpPipe(RT_PROF_CREATE_PIPE,pipe,RT_PROF_OK);
+#endif /* INCLUDE_PROVIEW */
+
+    /* Release protection against access to the list of created pipes.  */
+    TCT_Unprotect();
+
+    /* Return to user mode */
+    NU_USER_MODE();
+
+    /* Return successful completion.  */
+    return(NU_SUCCESS);
+}
+
+
+/*************************************************************************/
+/*                                                                       */
+/* FUNCTION                                                              */
+/*                                                                       */
+/*      PIC_Delete_Pipe                                                  */
+/*                                                                       */
+/* DESCRIPTION                                                           */
+/*                                                                       */
+/*      This function deletes a pipe and removes it from the list of     */
+/*      created pipes.  All tasks suspended on the pipe are              */
+/*      resumed.  Note that this function does not free the memory       */
+/*      associated with the pipe.                                        */
+/*                                                                       */
+/* CALLED BY                                                             */
+/*                                                                       */
+/*      Application                                                      */
+/*      PICE_Delete_Pipe                    Error checking shell         */
+/*                                                                       */
+/* CALLS                                                                 */
+/*                                                                       */
+/*      CSC_Remove_From_List                Remove node from list        */
+/*      [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_Protect                         Protect created list         */
+/*      TCT_Set_Current_Protect             Modify current protection    */
+/*      TCT_System_Protect                  Protect against system access*/
+/*      TCT_System_Unprotect                Release system protection    */
+/*      TCT_Unprotect                       Release protection           */
+/*                                                                       */
+/* INPUTS                                                                */
+/*                                                                       */
+/*      pipe_ptr                            Pipe control block pointer   */
+/*                                                                       */
+/* OUTPUTS                                                               */
+/*                                                                       */
+/*      NU_SUCCESS                                                       */
+/*                                                                       */
+/* 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  PIC_Delete_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 suspension block ptr */
+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_DELETE_PIPE_ID, (UNSIGNED) pipe,
+                                        (UNSIGNED) 0, (UNSIGNED) 0);
+
+#endif
+
+    /* Protect against access to the pipe.  */
+    TCT_System_Protect();
+
+#ifdef INCLUDE_PROVIEW
+    _RTProf_DumpPipe(RT_PROF_DELETE_PIPE,pipe,RT_PROF_OK);
+#endif /* INCLUDE_PROVIEW */
+
+    /* Clear the pipe ID.  */
+    pipe -> pi_id =  0;
+
+    /* Release protection.  */
+    TCT_Unprotect();
+
+    /* Protect against access to the list of created pipes.  */
+    TCT_Protect(&PID_List_Protect);
+
+    /* Remove the pipe from the list of created pipes.  */
+    CSC_Remove_From_List(&PID_Created_Pipes_List, &(pipe -> pi_created));
+
+    /* Decrement the total number of created pipes.  */
+    PID_Total_Pipes--;
+
+    /* Pickup the suspended task pointer list.  */
+    suspend_ptr =  pipe -> pi_suspension_list;
+
+    /* Walk the chain task(s) currently suspended on the pipe.  */
+    preempt =  0;
+    while (suspend_ptr)
+    {
+
+        /* Protect against system access.  */
+        TCT_System_Protect();
+
+        /* Resume the suspended task.  Insure that the status returned is
+           NU_PIPE_DELETED.  */
+        suspend_ptr -> pi_return_status =  NU_PIPE_DELETED;
+
+        /* 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
+
+            /* Setup the next suspension pointer.  */
+            suspend_ptr =  next_ptr;
+
+        /* Modify current protection.  */
+        TCT_Set_Current_Protect(&PID_List_Protect);
+
+        /* Clear the system protection.  */
+        TCT_System_Unprotect();
+    }
+
+    /* 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)
+    {
+
+        /* Protect against system access.  */
+        TCT_System_Protect();
+
+        /* Resume the suspended task.  Insure that the status returned is
+           NU_PIPE_DELETED.  */
+        suspend_ptr -> pi_return_status =  NU_PIPE_DELETED;
+
+        /* 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 suspend pointer to the next block.  */
+            suspend_ptr =  next_ptr;
+
+        /* Modify current protection.  */
+        TCT_Set_Current_Protect(&PID_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 pipes.  */
+    TCT_Unprotect();
+
+    /* Return to user mode */
+    NU_USER_MODE();
+
+    /* Return a successful completion.  */
+    return(NU_SUCCESS);
+}
+
+
+/*************************************************************************/
+/*                                                                       */
+/* FUNCTION                                                              */
+/*                                                                       */
+/*      PIC_Send_To_Pipe                                                 */
+/*                                                                       */
+/* DESCRIPTION                                                           */
+/*                                                                       */
+/*      This function sends a message to the specified pipe.  The        */
+/*      message length is determined by the caller.  If there are one    */
+/*      or more tasks suspended on the pipe for a message, the message   */
+/*      is copied into the message area of the first waiting task.  If   */
+/*      the task's request is satisfied, it is resumed.  Otherwise, if   */
+/*      the pipe cannot hold the message, suspension of the calling      */
+/*      task is an option of the caller.                                 */
+/*                                                                       */
+/* CALLED BY                                                             */
+/*                                                                       */
+/*      Application                                                      */
+/*      PICE_Send_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  PIC_Send_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         */
+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_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 make 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_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_SEND_TO_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_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_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++;
+
+#ifdef INCLUDE_PROVIEW
+        _RTProf_DumpPipe(RT_PROF_SEND_TO_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                                                              */
+/*                                                                       */
+/*      PIC_Receive_From_Pipe                                            */
+/*                                                                       */
+/* DESCRIPTION                                                           */
+/*                                                                       */
+/*      This function receives a message from the specified pipe.  The   */
+/*      size of the message is specified by the caller.  If there is a   */
+/*      message currently in the pipe, the message is removed from the   */
+/*      pipe and placed in the caller's area.  Suspension is possible    */
+/*      if the request cannot be satisfied.                              */
+/*                                                                       */
+/* CALLED BY                                                             */
+/*                                                                       */
+/*      Application                                                      */
+/*      PICE_Receive_From_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         */
+/*      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 the message          */
+/*      actual_size                         Size of message received     */
+/*      suspend                             Suspension option if empty   */
+/*                                                                       */
+/* OUTPUTS                                                               */
+/*                                                                       */
+/*      NU_SUCCESS                          If service is successful     */
+/*      NU_PIPE_EMPTY                       If pipe is currently empty   */
+/*      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  PIC_Receive_From_Pipe(NU_PIPE *pipe_ptr, VOID *message,
+                UNSIGNED size, UNSIGNED *actual_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    */
+TC_TCB         *task;                       /* Task pointer              */
+UNSIGNED        copy_size;                  /* Number of bytes to copy   */
+UNSIGNED        pad =  0;                   /* Number of pad bytes       */
+R4 INT          i;                          /* Working counter           */
+STATUS          preempt;                    /* Preemption 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_RECEIVE_FROM_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 urgent message request is currently suspended.  */
+    if (pipe -> pi_urgent_list)
+    {
+
+        /* If so, copy the message from the suspended request block and
+           resume the associated task.  */
+
+        /* Decrement the number of tasks waiting on pipe.  */
+        pipe -> pi_tasks_waiting--;
+
+        /* Remove the first suspended block from the list.  */
+        suspend_ptr =  pipe -> pi_urgent_list;
+        CSC_Remove_From_List((CS_NODE **) &(pipe -> pi_urgent_list),
+                                          &(suspend_ptr -> pi_suspend_link));
+
+        /* Setup the source and destination pointers.  */
+        destination =   (BYTE_PTR) message;
+        source =        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.  */
+        *actual_size =  suspend_ptr -> pi_message_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();
+    }
+
+    /* Determine if there are messages in the pipe.  */
+    else if (pipe -> pi_messages)
+    {
+
+        /* Copy message from pipe into the caller's area.  */
+
+        /* Setup the source and destination pointers.  */
+        destination =  (BYTE_PTR) message;
+        source =       pipe -> pi_read;
+
+        /* Process according to the type of message supported by the pipe.  */
+        if (pipe -> pi_fixed_size)
+        {
+
+            /* Pipe supports fixed-size messages.  */
+
+            /* Copy the message from the pipe area into the destination.  */
+            i =  (INT) size;
+            do
+            {
+                *(destination) =  *(source++);
+                if ((--i) == 0)
+                    break;
+                destination++;
+            } while (1);
+        }
+        else
+        {
+
+            /* Pipe supports variable-size messages.  */
+
+            /* Variable length message size is actually in the pipe area. */
+            size =  *((UNSIGNED *) source);
+            source =  source + sizeof(UNSIGNED);
+
+            /* Check for a wrap-around condition on the pipe.  */
+            if (source >= pipe -> pi_end)
+
+                /* Wrap the read pointer back to the top of the pipe
+                   area.  */
+                source =  pipe -> pi_start;
+
+            /* Increment the number of available bytes in the pipe.  */
+            pipe -> pi_available =  pipe -> pi_available + sizeof(UNSIGNED);
+
+            /* Calculate the number of pad bytes necessary to keep
+               the pipe read pointer on an UNSIGNED data element alignment.*/
+            pad =  (((size + sizeof(UNSIGNED) - 1)/sizeof(UNSIGNED)) *
+                    sizeof(UNSIGNED)) - size;
+
+            /* Calculate the number of bytes remaining from the read pointer
+               to the bottom of the pipe.  */
+            copy_size =  pipe -> pi_end - source;
+
+            /* 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;
+                    destination++;
+                } while (1);
+            }
+            else
+            {
+
+                /* Copy the first half of the message.  */
+                i =  (INT) copy_size;
+                do
+                {
+                    *(destination++) =  *(source);
+                    if ((--i) ==  0)
+                        break;
+                    source++;
+                } while (1);
+
+                /* Copy the second half of the message.  */
+                source =  pipe -> pi_start;
+                i =  (INT) (size - copy_size);
+                do
+                {
+                    *(destination) =  *(source++);
+                    if ((--i) == 0)
+                        break;
+                    destination++;
+                } while (1);
+            }
+        }
+
+        /* Check again for wrap-around condition on the read pointer. */
+        if (source >= pipe -> pi_end)
+
+            /* Move the read pointer to the top of the pipe area.  */
+            source =  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 read
+               pointer.  */
+
+            /* Calculate the number of bytes remaining from the read
+               pointer to the bottom of the pipe.  */
+            copy_size =  pipe -> pi_end - source;
+
+            /* 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 read pointer to the top of the pipe and make the
+                   necessary adjustment.  */
+                source =  pipe -> pi_start + (pad - copy_size);
+            else
+
+                /* There is enough room in the pipe to simply add the
+                   the pad bytes to the read pointer.  */
+                source =  source + pad;
+
+            /* Add pad bytes to the available bytes count.  */
+            pipe -> pi_available =  pipe -> pi_available + pad;
+        }
+
+        /* Adjust the actual read pointer.  */
+        pipe -> pi_read =  source;
+
+        /* Increment the number of available bytes.  */
+        pipe -> pi_available =  pipe -> pi_available + size;
+
+        /* Decrement the number of messages in the pipe.  */
+        pipe -> pi_messages--;
+
+        /* Return the number of bytes received.  */
+        *actual_size =  size;
+
+#ifdef INCLUDE_PROVIEW
+        _RTProf_DumpPipe(RT_PROF_RECEIVE_FROM_PIPE,pipe,RT_PROF_OK);
+#endif /* INCLUDE_PROVIEW */
+
+        /* Determine if any tasks suspended on a full pipe can be woken
+           up.  */
+        if (pipe -> pi_suspension_list)
+        {
+
+            /* Pickup the suspension list and examine suspension blocks
+               to see if the message could now fit in the pipe.  */
+            suspend_ptr =  pipe -> pi_suspension_list;
+            preempt =      NU_FALSE;
+            size =         suspend_ptr -> pi_message_size;
+            i =            0;
+            pad =          0;
+
+            /* Overhead of each pipe message.  */
+            if (!pipe -> pi_fixed_size)
+            {
+
+                /* 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);
+            }
+
+            while ((suspend_ptr) && ((size + i) <= pipe -> pi_available))
+            {
+
+                /* Place the suspended task's message into the pipe.  */
+
+                /* Setup the source and destination pointers.  */
+                source =       suspend_ptr -> pi_message_area;
+                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 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++;
+
+                /* Decrement the number of tasks waiting counter.  */
+                pipe -> pi_tasks_waiting--;
+
+                /* Remove the first suspended block from the list.  */
+                CSC_Remove_From_List((CS_NODE **)
+                    &(pipe -> pi_suspension_list),
+                                &(suspend_ptr -> pi_suspend_link));
+
+                /* Return a successful status.  */
+                suspend_ptr -> pi_return_status =  NU_SUCCESS;
+
+                /* Resume the suspended task.  */
+                preempt =  preempt |
+                 TCC_Resume_Task((NU_TASK *) suspend_ptr -> pi_suspended_task,
+                                                       NU_PIPE_SUSPEND);
+
+                /* Setup suspend pointer to the head of the list.  */
+                suspend_ptr =  pipe -> pi_suspension_list;
+
+                /* Determine if there really is another suspended block.  If
+                   there is and the pipe supports variable length messages,
+                   calculate new size and padding parameters.  */
+                if ((suspend_ptr) && (!pipe -> pi_fixed_size))
+                {
+
+                    /* Get the next message size.  */
+                    size =   suspend_ptr -> pi_message_size;
+
+                    /* 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);
+                }
+            }
+
+            /* Determine if a preempt condition is present.  */
+            if (preempt)
+
+                /* Transfer control to the system if the resumed task function
+                   detects a preemption condition.  */
+                TCT_Control_To_System();
+        }
+    }
+    else
+    {
+
+        /* pipe is empty.  Determine if the task wants to suspend.  */
+        if (suspend)
+        {
+
+            /* Increment the number of tasks waiting on the pipe counter. */
+            pipe -> pi_tasks_waiting++;
+
+#ifdef INCLUDE_PROVIEW
+            _RTProf_DumpPipe(RT_PROF_RECEIVE_FROM_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 status of the request.  */
+            status =  suspend_ptr -> pi_return_status;
+            *actual_size =  suspend_ptr -> pi_actual_size;
+        }
+        else
+        {
+
+            /* Return a status of NU_PIPE_EMPTY because there are no
+               messages in the pipe.  */
+            status =  NU_PIPE_EMPTY;
+
+#ifdef INCLUDE_PROVIEW
+            _RTProf_DumpPipe(RT_PROF_RECEIVE_FROM_PIPE,pipe,RT_PROF_FAIL);
+#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                                                              */
+/*                                                                       */
+/*      PIC_Cleanup                                                      */
+/*                                                                       */
+/* DESCRIPTION                                                           */
+/*                                                                       */
+/*      This function is responsible for removing a suspension block     */
+/*      from a pipe.  It is not called unless a timeout or a task        */
+/*      terminate is in progress.  Note that protection is already in    */
+/*      effect - the same protection at suspension time.  This routine   */
+/*      must be called from Supervisor mode in Supervisor/User mode      */
+/*      switching kernels.                                               */
+/*                                                                       */
+/* CALLED BY                                                             */
+/*                                                                       */
+/*      TCC_Timeout                         Task timeout                 */
+/*      TCC_Terminate                       Task terminate               */
+/*                                                                       */
+/* CALLS                                                                 */
+/*                                                                       */
+/*      CSC_Remove_From_List                Remove suspend block from    */
+/*                                            the suspension list        */
+/*                                                                       */
+/* INPUTS                                                                */
+/*                                                                       */
+/*      information                         Pointer to suspend block     */
+/*                                                                       */
+/* OUTPUTS                                                               */
+/*                                                                       */
+/*      None                                                             */
+/*                                                                       */
+/* HISTORY                                                               */
+/*                                                                       */
+/*        DATE                    REMARKS                                */
+/*                                                                       */
+/*      03-01-1993      Created initial version 1.0                      */
+/*      04-19-1993      Verified version 1.0                             */
+/*                                                                       */
+/*************************************************************************/
+VOID  PIC_Cleanup(VOID *information)
+{
+
+PI_SUSPEND      *suspend_ptr;               /* Suspension block pointer  */
+NU_SUPERV_USER_VARIABLES
+
+    /* Switch to supervisor mode */
+    NU_SUPERVISOR_MODE();
+
+    /* Use the information pointer as a suspend pointer.  */
+    suspend_ptr =  (PI_SUSPEND *) information;
+
+    /* By default, indicate that the service timed-out.  It really does not
+       matter if this function is called from a terminate request since
+       the task does not resume.  */
+    suspend_ptr -> pi_return_status =  NU_TIMEOUT;
+
+    /* Decrement the number of tasks waiting counter.  */
+    (suspend_ptr -> pi_pipe) -> pi_tasks_waiting--;
+
+    /* Determine if the suspend block is one the urgent list. */
+    if ((suspend_ptr -> pi_pipe) -> pi_urgent_list)
+    {
+        /* Unlink the suspend block from the urgent list.  */
+        CSC_Remove_From_List((CS_NODE **) 
+                    &((suspend_ptr -> pi_pipe) -> pi_urgent_list), 
+                                    &(suspend_ptr -> pi_suspend_link));
+    }
+    else
+    {
+        /* Unlink the suspend block from the suspension list.  */
+        CSC_Remove_From_List((CS_NODE **) 
+                    &((suspend_ptr -> pi_pipe) -> pi_suspension_list), 
+                                    &(suspend_ptr -> pi_suspend_link));
+    }
+
+    /* Return to user mode */
+    NU_USER_MODE();
+}
+
+
+
+
+
+
+