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#if 0
/*
* 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.rtems.com/license/LICENSE.
*
* $Id$
*/
#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,
uintptr_t user_addr,
uintptr_t aligned_user_addr,
uintptr_t size
)
{
uintptr_t const user_area = _Heap_Alloc_area_of_block(the_block);
uintptr_t const block_end = (uintptr_t) the_block
+ _Heap_Block_size(the_block) + HEAP_BLOCK_SIZE_OFFSET;
uintptr_t const user_end = aligned_user_addr + size;
uintptr_t const heap_start = (uintptr_t) the_heap->start + HEAP_BLOCK_HEADER_SIZE;
uintptr_t const heap_end = (uintptr_t) the_heap->final
+ HEAP_BLOCK_SIZE_OFFSET;
uintptr_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) */
/*
* Allocate block of size 'alloc_size' from 'the_block' belonging to
* 'the_heap'. Split 'the_block' if possible, otherwise allocate it entirely.
* When split, make the upper part used, and leave the lower part free.
* Return the block allocated.
*
* NOTE: this is similar to _Heap_Block_allocate(), except it makes different
* part of the split block used, and returns address of the block instead of its
* size. We do need such variant for _Heap_Allocate_aligned() as we can't allow
* user pointer to be too far from the beginning of the block, so that we can
* recover start-of-block address from the user pointer without additional
* information stored in the heap.
*/
static
Heap_Block *block_allocate(
Heap_Control *the_heap,
Heap_Block *the_block,
uintptr_t alloc_size
)
{
Heap_Statistics *const stats = &the_heap->stats;
uintptr_t const block_size = _Heap_Block_size(the_block);
uintptr_t const the_rest = block_size - alloc_size;
_HAssert(_Heap_Is_aligned(block_size, the_heap->page_size));
_HAssert(_Heap_Is_aligned(alloc_size, the_heap->page_size));
_HAssert(alloc_size <= block_size);
_HAssert(_Heap_Is_prev_used(the_block));
if (the_rest >= the_heap->min_block_size) {
/* Split the block so that lower part is still free, and upper part
becomes used. */
the_block->size_and_flag = the_rest | HEAP_PREV_BLOCK_USED;
the_block = _Heap_Block_at(the_block, the_rest);
the_block->prev_size = the_rest;
the_block->size_and_flag = alloc_size;
} else {
/* Don't split the block as remainder is either zero or too small to be
used as a separate free block. Change 'alloc_size' to the size of the
block and remove the block from the list of free blocks. */
_Heap_Free_list_remove(the_block);
alloc_size = block_size;
stats->free_blocks -= 1;
}
/* Mark the block as used (in the next block). */
_Heap_Block_at(the_block, alloc_size)->size_and_flag |= HEAP_PREV_BLOCK_USED;
/* Update statistics */
stats->free_size -= alloc_size;
if (stats->min_free_size > stats->free_size)
stats->min_free_size = stats->free_size;
stats->used_blocks += 1;
return the_block;
}
/*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,
uintptr_t size,
uintptr_t alignment
)
{
uintptr_t search_count;
Heap_Block *the_block;
void *user_ptr = NULL;
uintptr_t const page_size = the_heap->page_size;
Heap_Statistics *const stats = &the_heap->stats;
Heap_Block *const tail = _Heap_Free_list_tail(the_heap);
uintptr_t const end_to_user_offs = size - HEAP_BLOCK_SIZE_OFFSET;
uintptr_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_Free_list_first(the_heap), search_count = 0;
the_block != tail;
the_block = the_block->next, ++search_count)
{
uintptr_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. */
uintptr_t user_addr;
uintptr_t aligned_user_addr;
uintptr_t const user_area = _Heap_Alloc_area_of_block(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. */
uintptr_t const block_end = (uintptr_t) the_block + block_size;
aligned_user_addr =
_Heap_Align_down(block_end - end_to_user_offs, 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 = _Heap_Align_down(aligned_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 = _Heap_Align_up(user_addr, alignment);
if (aligned_user_addr - user_addr >= page_size) {
/* No, we can't use the block */
continue;
}
}
}
/* The block is indeed acceptable: calculate the size of the block
to be allocated and perform allocation. */
uintptr_t const alloc_size =
block_end - user_addr + HEAP_BLOCK_HEADER_SIZE;
_HAssert(_Heap_Is_aligned(aligned_user_addr, alignment));
the_block = 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;
}
#endif
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