/*
* 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.
*
* $Id$
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/system.h>
#include <rtems/score/sysstate.h>
#include <rtems/score/heap.h>
#if defined(RTEMS_HEAP_DEBUG)
static void
check_result(
Heap_Control* the_heap,
Heap_Block* the_block,
_H_uptr_t user_addr,
_H_uptr_t aligned_user_addr,
uint32_t size)
{
_H_uptr_t const user_area = _H_p2u(_Heap_User_area(the_block));
_H_uptr_t const block_end = _H_p2u(the_block)
+ _Heap_Block_size(the_block) + HEAP_BLOCK_HEADER_OFFSET;
_H_uptr_t const user_end = aligned_user_addr + size;
_H_uptr_t const heap_start = _H_p2u(the_heap->start) + HEAP_OVERHEAD;
_H_uptr_t const heap_end = _H_p2u(the_heap->final)
+ HEAP_BLOCK_HEADER_OFFSET;
uint32_t const page_size = the_heap->page_size;
_HAssert(user_addr == user_area);
_HAssert(aligned_user_addr - user_area < page_size);
_HAssert(aligned_user_addr >= user_area);
_HAssert(aligned_user_addr < block_end);
_HAssert(user_end > user_area);
_HAssert(user_end <= block_end);
_HAssert(aligned_user_addr >= heap_start);
_HAssert(aligned_user_addr < heap_end);
_HAssert(user_end > heap_start);
_HAssert(user_end <= heap_end);
}
#else /* !defined(RTEMS_HEAP_DEBUG) */
#define check_result(a, b, c, d, e) ((void)0)
#endif /* !defined(RTEMS_HEAP_DEBUG) */
/*PAGE
*
* _Heap_Allocate_aligned
*
* This kernel routine allocates the requested size of memory
* from the specified heap so that returned address is aligned according to
* the 'alignment'.
*
* Input parameters:
* the_heap - pointer to the heap control block.
* size - size in bytes of the memory block to allocate.
* alignment - required user pointer alignment in bytes
*
* Output parameters:
* returns - starting address of memory block allocated. The address is
* aligned on specified boundary.
*/
void *_Heap_Allocate_aligned(
Heap_Control *the_heap,
uint32_t size,
uint32_t alignment
)
{
uint32_t search_count;
Heap_Block *the_block;
void *user_ptr = NULL;
uint32_t const page_size = the_heap->page_size;
Heap_Statistics *const stats = &the_heap->stats;
Heap_Block *const tail = _Heap_Tail(the_heap);
uint32_t const end_to_user_offs = size - HEAP_BLOCK_HEADER_OFFSET;
uint32_t const the_size =
_Heap_Calc_block_size(size, page_size, the_heap->min_block_size);
if(the_size == 0)
return NULL;
if(alignment == 0)
alignment = CPU_ALIGNMENT;
/* Find large enough free block that satisfies the alignment requirements. */
for(the_block = _Heap_Head(the_heap)->next, search_count = 0;
the_block != tail;
the_block = the_block->next, ++search_count)
{
uint32_t const block_size = _Heap_Block_size(the_block);
/* As we always coalesce free blocks, prev block must have been used. */
_HAssert(_Heap_Is_prev_used(the_block));
if(block_size >= the_size) { /* the_block is large enough. */
_H_uptr_t user_addr;
_H_uptr_t aligned_user_addr;
_H_uptr_t const user_area = _H_p2u(_Heap_User_area(the_block));
/* Calculate 'aligned_user_addr' that will become the user pointer we
return. It should be at least 'end_to_user_offs' bytes less than the
the 'block_end' and should be aligned on 'alignment' boundary.
Calculations are from the 'block_end' as we are going to split free
block so that the upper part of the block becomes used block. */
_H_uptr_t const block_end = _H_p2u(the_block) + block_size;
aligned_user_addr = block_end - end_to_user_offs;
_Heap_Align_down_uptr(&aligned_user_addr, alignment);
/* 'user_addr' is the 'aligned_user_addr' further aligned down to the
'page_size' boundary. We need it as blocks' user areas should begin
only at 'page_size' aligned addresses */
user_addr = aligned_user_addr;
_Heap_Align_down_uptr(&user_addr, page_size);
/* Make sure 'user_addr' calculated didn't run out of 'the_block. */
if(user_addr >= user_area) {
/* The block seems to be acceptable. Check if the remainder of
'the_block' is less than 'min_block_size' so that 'the_block' won't
actually be split at the address we assume. */
if(user_addr - user_area < the_heap->min_block_size) {
/* The block won't be split, so 'user_addr' will be equal to the
'user_area'. */
user_addr = user_area;
/* We can't allow the distance between 'user_addr' and
'aligned_user_addr' to be outside of [0,page_size) range. If we do,
we will need to store this distance somewhere to be able to
resurrect the block address from the user pointer. (Having the
distance within [0,page_size) range allows resurrection by
aligning user pointer down to the nearest 'page_size' boundary.) */
if(aligned_user_addr - user_addr >= page_size) {
/* The user pointer will be too far from 'user_addr'. See if we
can make 'aligned_user_addr' to be close enough to the
'user_addr'. */
aligned_user_addr = user_addr;
_Heap_Align_up_uptr(&aligned_user_addr, alignment);
if(aligned_user_addr - user_addr >= page_size) {
/* No, we can't use the block */
aligned_user_addr = 0;
}
}
}
if(aligned_user_addr) {
/* The block is indeed acceptable: calculate the size of the block
to be allocated and perform allocation. */
uint32_t const alloc_size =
block_end - user_addr + HEAP_BLOCK_USER_OFFSET;
_HAssert(_Heap_Is_aligned_ptr((void*)aligned_user_addr, alignment));
(void)_Heap_Block_allocate(the_heap, the_block, alloc_size);
stats->searches += search_count + 1;
stats->allocs += 1;
check_result(the_heap, the_block, user_addr,
aligned_user_addr, size);
user_ptr = (void*)aligned_user_addr;
break;
}
}
}
}
if(stats->max_search < search_count)
stats->max_search = search_count;
return user_ptr;
}
