dmc.c

test file nucleus source

#endif

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

    /* Adjust the request to a size evenly divisible by the number of bytes
       in an UNSIGNED data element.  Also, check to make sure it is of the
       minimum size.  */
    if (size < pool -> dm_min_allocation)

        /* Change size to the minimum allocation.  */
        size =  pool -> dm_min_allocation;
    else

        /* Insure that size is a multiple of the UNSIGNED size.  */
        size =
           ((size + sizeof(UNSIGNED) - 1)/sizeof(UNSIGNED)) * sizeof(UNSIGNED);

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

    /* Search the memory list for the first available block of memory that
       satisfies the request.  Note that blocks are merged during the
       deallocation function.  */
    memory_ptr =  pool -> dm_search_ptr;
    do
    {

        /* Determine if the block is free and if it can satisfy the request. */
        if (memory_ptr -> dm_memory_free)

            /* Calculate the free block size.  */
            free_size =  (((BYTE_PTR) (memory_ptr -> dm_next_memory)) -
                           ((BYTE_PTR) memory_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.  */
            memory_ptr =  memory_ptr -> dm_next_memory;
    } while((free_size < size) && (memory_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) memory_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 =  memory_ptr;
            new_ptr -> dm_next_memory =      memory_ptr -> dm_next_memory;
            (new_ptr -> dm_next_memory) -> dm_previous_memory =  new_ptr;
            memory_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.  */
        memory_ptr -> dm_memory_free =  NU_FALSE;

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

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

        /* Return a memory address to the caller.  */
        *return_pointer =  (VOID *) (((BYTE_PTR) memory_ptr) + DM_OVERHEAD);
#ifdef INCLUDE_PROVIEW
        _RTProf_DumpMemoryPool(RT_PROF_ALLOCATE_MEMORY,pool,RT_PROF_OK);
#endif /*INCLUDE_PROVIEW*/
    }
    else
    {

        /* Enough dynamic memory is not available.  Determine if suspension is
           required. */
        if (suspend)
        {

            /* Suspension is selected.  */

            /* Increment the number of tasks waiting.  */
            pool -> dm_tasks_waiting++;

#ifdef INCLUDE_PROVIEW
            _RTProf_DumpMemoryPool(RT_PROF_ALLOCATE_MEMORY,pool,RT_PROF_WAIT);
#endif /*INCLUDE_PROVIEW*/
            /* Setup the suspend block and suspend the calling task.  */
            suspend_ptr =  &suspend_block;
            suspend_ptr -> dm_memory_pool =              pool;
            suspend_ptr -> dm_request_size =             size;
            suspend_ptr -> dm_suspend_link.cs_next =     NU_NULL;
            suspend_ptr -> dm_suspend_link.cs_previous = NU_NULL;
            task =                            (TC_TCB *) TCT_Current_Thread();
            suspend_ptr -> dm_suspended_task =           task;

            /* Determine if priority or FIFO suspension is associated with the
               memory pool.  */
            if (pool -> dm_fifo_suspend)
            {

                /* FIFO suspension is required.  Link the suspend block into
                   the list of suspended tasks on this memory pool.  */
                CSC_Place_On_List((CS_NODE **)
                        &(pool -> dm_suspension_list),
                                        &(suspend_ptr -> dm_suspend_link));
            }
            else
            {

                /* Get the priority of the current thread so the suspend block
                   can be placed in the appropriate place.  */
                suspend_ptr -> dm_suspend_link.cs_priority =
                                                     TCC_Task_Priority(task);

                CSC_Priority_Place_On_List((CS_NODE **)
                        &(pool -> dm_suspension_list),
                                        &(suspend_ptr -> dm_suspend_link));
            }

            /* Protect against system access.  */
            TCT_System_Protect();

            /* Save the list protection in preparation for suspension.  */
            TCT_Set_Suspend_Protect(&(pool -> dm_protect));

            /* Release protection of dynamic memory pool.  */
            TCT_Unprotect_Specific(&(pool -> dm_protect));

            /* Finally, suspend the calling task. Note that the suspension call
               automatically clears the system protection.  */
            TCC_Suspend_Task((NU_TASK *) task, NU_MEMORY_SUSPEND,
                                        DMC_Cleanup, suspend_ptr, suspend);

            /* Pickup the return status.  */
            status =            suspend_ptr -> dm_return_status;
            *return_pointer =   suspend_ptr -> dm_return_pointer;
        }
        else
        {

            /* No suspension requested.  Simply return an error status.  */
            status =            NU_NO_MEMORY;
            *return_pointer =   NU_NULL;
#ifdef INCLUDE_PROVIEW
            _RTProf_DumpMemoryPool(RT_PROF_ALLOCATE_MEMORY,pool,RT_PROF_FAIL);
#endif /*INCLUDE_PROVIEW*/
        }
    }

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

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

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


/*************************************************************************/
/*                                                                       */
/* FUNCTION                                                              */
/*                                                                       */
/*      DMC_Deallocate_Memory                                            */
/*                                                                       */
/* DESCRIPTION                                                           */
/*                                                                       */
/*      This function deallocates a previously allocated dynamic memory  */
/*      block.  The deallocated dynamic memory block is merged with any  */
/*      adjacent neighbors.  This insures that there are no consecutive  */
/*      blocks of free memory in the pool (makes the search easier!).    */
/*      If there is a task waiting for dynamic memory, a determination   */
/*      of whether or not the request can now be satisfied is made after */
/*      the deallocation is complete.                                    */
/*                                                                       */
/* CALLED BY                                                             */
/*                                                                       */
/*      Application                                                      */
/*      DMCE_Deallocate_Memory              Error checking shell         */
/*                                                                       */
/* CALLS                                                                 */
/*                                                                       */
/*      CSC_Remove_From_List                Remove from suspend 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_Set_Current_Protect             Set current protection       */
/*      TCT_System_Protect                  Protect system structures    */
/*      TCT_System_Unprotect                Release system protection    */
/*      TCT_Protect                         Protect dynamic memory pool  */
/*      TCT_Unprotect                       Release protection           */
/*                                                                       */
/* INPUTS                                                                */
/*                                                                       */
/*      memory                              Pointer to dynamic memory    */
/*                                                                       */
/* OUTPUTS                                                               */
/*                                                                       */
/*      NU_SUCCESS                                                       */
/*                                                                       */
/* HISTORY                                                               */
/*                                                                       */
/*         DATE                    REMARKS                               */
/*                                                                       */
/*      03-01-1993      Created initial version 1.0                      */
/*      04-19-1993      Verified version 1.0                             */
/*      03-01-1994      Added register options, changed                  */
/*                      protection logic to reduce                       */
/*                      overhead, resulting in                           */
/*                      version 1.1                                      */
/*                                                                       */
/*      03-18-1994      Verified version 1.1                             */
/*                                                                       */
/*************************************************************************/
STATUS  DMC_Deallocate_Memory(VOID *memory)
{

R1 DM_PCB      *pool;                       /* Pool pointer              */
R3 DM_SUSPEND  *suspend_ptr;                /* Pointer to suspend block  */
R2 DM_HEADER   *header_ptr;                 /* Pointer to memory hdr     */
R4 DM_HEADER   *new_ptr;                    /* New memory block pointer  */
UNSIGNED        size;                       /* Suspended task request    */
UNSIGNED        free_size;                  /* Amount of free bytes      */
STATUS          preempt;                    /* Preemption flag           */
STATUS          status;                     /* Completion status         */
NU_SUPERV_USER_VARIABLES

    /* Switch to supervisor mode */
    NU_SUPERVISOR_MODE();

#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_DEALLOCATE_MEMORY_ID, (UNSIGNED) memory,
                                        (UNSIGNED) 0, (UNSIGNED) 0);