dmc.c

test file nucleus source

#endif

    /* Initialize the status as successful.  */
    status =  NU_SUCCESS;

    /* Pickup the associated pool's pointer.  It is inside the header of
       each memory.  */
    header_ptr =  (DM_HEADER *) (((BYTE_PTR) memory) - DM_OVERHEAD);
    pool =        header_ptr -> dm_memory_pool;

    /* Protect against simultaneous access to the memory pool.  */
    TCT_Protect(&(pool -> dm_protect));

    /* Mark the memory as available.  */
    header_ptr -> dm_memory_free =  NU_TRUE;

    /* Adjust the available number of bytes.  */
    pool -> dm_available =  pool -> dm_available +
                        (((BYTE_PTR) (header_ptr -> dm_next_memory)) -
                           ((BYTE_PTR) header_ptr)) - DM_OVERHEAD;

    /* Determine if the block can be merged with the previous neighbor.  */
    if ((header_ptr -> dm_previous_memory) -> dm_memory_free)
    {

        /* Adjust the available number of bytes.  */
        pool -> dm_available =  pool -> dm_available + DM_OVERHEAD;

        /* Yes, merge block with previous neighbor.  */
        (header_ptr -> dm_previous_memory) -> dm_next_memory =
                                header_ptr -> dm_next_memory;
        (header_ptr -> dm_next_memory) -> dm_previous_memory =
                                header_ptr -> dm_previous_memory;

        /* Move header pointer to previous.  */
        header_ptr =  header_ptr -> dm_previous_memory;

        /* Adjust the search pointer to the new merged block.  */
        pool -> dm_search_ptr =  header_ptr;
    }

    /* Determine if the block can be merged with the next neighbor.  */
    if ((header_ptr -> dm_next_memory) -> dm_memory_free)
    {

        /* Adjust the available number of bytes.  */
        pool -> dm_available =  pool -> dm_available + DM_OVERHEAD;

        /* Yes, merge block with next neighbor.  */
        new_ptr =  header_ptr -> dm_next_memory;
        (new_ptr -> dm_next_memory) -> dm_previous_memory =
                                                header_ptr;
        header_ptr -> dm_next_memory = new_ptr -> dm_next_memory;

        /* Adjust the search pointer to the new merged block.  */
        pool -> dm_search_ptr =  header_ptr;
    }

#ifdef INCLUDE_PROVIEW
    _RTProf_DumpMemoryPool(RT_PROF_DEALLOCATE_MEMORY,pool,RT_PROF_OK);
#endif /*INCLUDE_PROVIEW*/
    /* Determine if another task is waiting for memory from the pool.  */
    suspend_ptr =  pool -> dm_suspension_list;
    preempt =      0;
    while (suspend_ptr)
    {

        /* Yes, another task is waiting for memory from the pool.  Search
           the pool in the same manner as the memory allocation function.  */
        size =        suspend_ptr -> dm_request_size;
        header_ptr =  pool -> dm_search_ptr;
        do
        {

            /* Determine if the block is free and if it can satisfy the request
               of the first task waiting. */
            if (header_ptr -> dm_memory_free)

                /* Calculate the free block size.  */
                free_size =  (((BYTE_PTR) (header_ptr -> dm_next_memory)) -
                               ((BYTE_PTR) header_ptr)) - DM_OVERHEAD;
            else

                /* There are no free bytes available.  */
                free_size =  0;

            /* Determine if the search should continue.  */
            if (free_size < size)

                /* Large enough block has not been found.  Move the search
                   pointer to the next block.  */
                header_ptr =  header_ptr -> dm_next_memory;
        } while((free_size < size) && (header_ptr != pool -> dm_search_ptr));

        /* Determine if the memory is available.  */
        if (free_size >= size)
        {

            /* A block that satisfies the request has been found.  */

            /* Determine if the block needs to be split.  */
            if (free_size >= (size + DM_OVERHEAD + pool -> dm_min_allocation))
            {

                /* Yes, split the block.  */
                new_ptr =  (DM_HEADER *) (((BYTE_PTR) header_ptr) + size +
                                                                  DM_OVERHEAD);

                /* Mark the new block as free.  */
                new_ptr -> dm_memory_free =  NU_TRUE;

                /* Put the pool pointer into the new block.  */
                new_ptr -> dm_memory_pool =  pool;

                /* Build the necessary pointers.  */
                new_ptr -> dm_previous_memory =  header_ptr;
                new_ptr -> dm_next_memory =      header_ptr -> dm_next_memory;
                (new_ptr -> dm_next_memory) -> dm_previous_memory =  new_ptr;
                header_ptr -> dm_next_memory =   new_ptr;

                /* Decrement the available byte count.  */
                pool -> dm_available =  pool -> dm_available -
                                                        size - DM_OVERHEAD;
            }
            else

                /* Decrement the entire free size from the available bytes
                   count.  */
                pool -> dm_available =  pool -> dm_available - free_size;

            /* Mark the allocated block as not available.  */
            header_ptr -> dm_memory_free =  NU_FALSE;

            /* Should the search pointer be moved?   */
            if (pool -> dm_search_ptr == header_ptr)

                /* Move the search pointer to the next free memory slot.  */
                pool -> dm_search_ptr =  header_ptr -> dm_next_memory;

            /* Decrement the number of tasks waiting counter.  */
            pool -> dm_tasks_waiting--;

            /* Remove the first suspended block from the list.  */
            CSC_Remove_From_List((CS_NODE **) &(pool -> dm_suspension_list),
                                        &(suspend_ptr -> dm_suspend_link));

            /* Setup the appropriate return value.  */
            suspend_ptr -> dm_return_status =   NU_SUCCESS;
            suspend_ptr -> dm_return_pointer =  (VOID *)
                                (((BYTE_PTR) header_ptr) + DM_OVERHEAD);

            /* Setup system protect while task is being resumed.  */
            TCT_System_Protect();

            /* Resume the suspended task.  */
            preempt =  preempt |
              TCC_Resume_Task((NU_TASK *) suspend_ptr -> dm_suspended_task,
                                                        NU_MEMORY_SUSPEND);

            /* Switch back to the pool protection.  */
            TCT_Set_Current_Protect(&(pool -> dm_protect));

            /* Release system protection.  */
            TCT_System_Unprotect();

            /* Pickup the next suspension pointer.  */
            suspend_ptr =  pool -> dm_suspension_list;
        }
        else

            /* Not enough memory for suspended task. */
            suspend_ptr =  NU_NULL;
    }

    /* 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();

    /* Release protection of the memory pool.  */
    TCT_Unprotect();

    /* Return to user mode */
    NU_USER_MODE();

    /* Return the completion status.  */
    return(status);
}


/*************************************************************************/
/*                                                                       */
/* FUNCTION                                                              */
/*                                                                       */
/*      DMC_Cleanup                                                      */
/*                                                                       */
/* DESCRIPTION                                                           */
/*                                                                       */
/*      This function is responsible for removing a suspension block     */
/*      from a memory pool.  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.      */
/*                                                                       */
/* 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  DMC_Cleanup(VOID *information)
{

DM_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 =  (DM_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 -> dm_return_status =   NU_TIMEOUT;
    suspend_ptr -> dm_return_pointer =  NU_NULL;

    /* Decrement the number of tasks waiting counter.  */
    (suspend_ptr -> dm_memory_pool) -> dm_tasks_waiting--;

    /* Unlink the suspend block from the suspension list.  */
    CSC_Remove_From_List((CS_NODE **)
                &((suspend_ptr -> dm_memory_pool) -> dm_suspension_list),
                                &(suspend_ptr -> dm_suspend_link));

    /* Return to user mode */
    NU_USER_MODE();
}