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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [exec/] [score/] [src/] [heapextend.c] - Rev 580
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/* * Heap Handler * * COPYRIGHT (c) 1989-1999. * On-Line Applications Research Corporation (OAR). * * The license and distribution terms for this file may be * found in the file LICENSE in this distribution or at * http://www.OARcorp.com/rtems/license.html. * * $Id: heapextend.c,v 1.2 2001-09-27 11:59:34 chris Exp $ */ #include <rtems/system.h> #include <rtems/score/sysstate.h> #include <rtems/score/heap.h> /*PAGE * * _Heap_Extend * * This routine grows the_heap memory area using the size bytes which * begin at starting_address. * * Input parameters: * the_heap - pointer to heap header. * starting_address - pointer to the memory area. * size - size in bytes of the memory block to allocate. * * Output parameters: * *amount_extended - amount of memory added to the_heap */ Heap_Extend_status _Heap_Extend( Heap_Control *the_heap, void *starting_address, unsigned32 size, unsigned32 *amount_extended ) { Heap_Block *the_block; unsigned32 *p; /* * The overhead was taken from the original heap memory. */ Heap_Block *old_final; Heap_Block *new_final; /* * There are five possibilities for the location of starting * address: * * 1. non-contiguous lower address (NOT SUPPORTED) * 2. contiguous lower address (NOT SUPPORTED) * 3. in the heap (ERROR) * 4. contiguous higher address (SUPPORTED) * 5. non-contiguous higher address (NOT SUPPORTED) * * As noted, this code only supports (4). */ if ( starting_address >= (void *) the_heap->start && /* case 3 */ starting_address <= (void *) the_heap->final ) return HEAP_EXTEND_ERROR; if ( starting_address < (void *) the_heap->start ) { /* cases 1 and 2 */ return HEAP_EXTEND_NOT_IMPLEMENTED; /* cases 1 and 2 */ } else { /* cases 4 and 5 */ the_block = (Heap_Block *) _Addresses_Subtract_offset( starting_address, HEAP_OVERHEAD ); if ( the_block != the_heap->final ) return HEAP_EXTEND_NOT_IMPLEMENTED; /* case 5 */ } /* * Currently only case 4 should make it to this point. * The basic trick is to make the extend area look like a used * block and free it. */ *amount_extended = size; old_final = the_heap->final; new_final = _Addresses_Add_offset( old_final, size ); /* SAME AS: _Addresses_Add_offset( starting_address, size-HEAP_OVERHEAD ); */ the_heap->final = new_final; old_final->front_flag = new_final->back_flag = _Heap_Build_flag( size, HEAP_BLOCK_USED ); new_final->front_flag = HEAP_DUMMY_FLAG; /* * Must pass in address of "user" area * So add in the offset field. */ p = (unsigned32 *) &old_final->next; *p = sizeof(unsigned32); p++; _Heap_Free( the_heap, p ); return HEAP_EXTEND_SUCCESSFUL; }
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