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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [exec/] [score/] [src/] [heapfree.c] - Rev 227
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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: heapfree.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_Free * * This kernel routine returns the memory designated by the * given heap and given starting address to the memory pool. * * Input parameters: * the_heap - pointer to heap header * starting_address - starting address of the memory block to free. * * Output parameters: * TRUE - if starting_address is valid heap address * FALSE - if starting_address is invalid heap address */ boolean _Heap_Free( Heap_Control *the_heap, void *starting_address ) { Heap_Block *the_block; Heap_Block *next_block; Heap_Block *new_next_block; Heap_Block *previous_block; Heap_Block *temporary_block; unsigned32 the_size; the_block = _Heap_User_block_at( starting_address ); if ( !_Heap_Is_block_in( the_heap, the_block ) || _Heap_Is_block_free( the_block ) ) { return( FALSE ); } the_size = _Heap_Block_size( the_block ); next_block = _Heap_Block_at( the_block, the_size ); if ( !_Heap_Is_block_in( the_heap, next_block ) || (the_block->front_flag != next_block->back_flag) ) { return( FALSE ); } if ( _Heap_Is_previous_block_free( the_block ) ) { previous_block = _Heap_Previous_block( the_block ); if ( !_Heap_Is_block_in( the_heap, previous_block ) ) { return( FALSE ); } if ( _Heap_Is_block_free( next_block ) ) { /* coalesce both */ previous_block->front_flag += next_block->front_flag + the_size; temporary_block = _Heap_Next_block( previous_block ); temporary_block->back_flag = previous_block->front_flag; next_block->next->previous = next_block->previous; next_block->previous->next = next_block->next; } else { /* coalesce prev */ previous_block->front_flag = next_block->back_flag = previous_block->front_flag + the_size; } } else if ( _Heap_Is_block_free( next_block ) ) { /* coalesce next */ the_block->front_flag = the_size + next_block->front_flag; new_next_block = _Heap_Next_block( the_block ); new_next_block->back_flag = the_block->front_flag; the_block->next = next_block->next; the_block->previous = next_block->previous; next_block->previous->next = the_block; next_block->next->previous = the_block; if (the_heap->first == next_block) the_heap->first = the_block; } else { /* no coalesce */ next_block->back_flag = the_block->front_flag = the_size; the_block->previous = _Heap_Head( the_heap ); the_block->next = the_heap->first; the_heap->first = the_block; the_block->next->previous = the_block; } return( TRUE ); }
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