diff options
Diffstat (limited to 'cpukit/score/src/heapallocatealigned.c')
| -rw-r--r-- | cpukit/score/src/heapallocatealigned.c | 61 |
1 files changed, 58 insertions, 3 deletions
diff --git a/cpukit/score/src/heapallocatealigned.c b/cpukit/score/src/heapallocatealigned.c index 2d0fb66f42..3fda404490 100644 --- a/cpukit/score/src/heapallocatealigned.c +++ b/cpukit/score/src/heapallocatealigned.c @@ -56,6 +56,61 @@ check_result( #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, + uint32_t alloc_size) +{ + Heap_Statistics *const stats = &the_heap->stats; + uint32_t const block_size = _Heap_Block_size(the_block); + uint32_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 = the_rest | HEAP_PREV_USED; + the_block = _Heap_Block_at(the_block, the_rest); + the_block->prev_size = the_rest; + the_block->size = 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_Block_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 |= HEAP_PREV_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 @@ -101,7 +156,7 @@ void *_Heap_Allocate_aligned( /* Find large enough free block that satisfies the alignment requirements. */ - for(the_block = _Heap_Head(the_heap)->next, search_count = 0; + for(the_block = _Heap_First(the_heap), search_count = 0; the_block != tail; the_block = the_block->next, ++search_count) { @@ -131,7 +186,7 @@ void *_Heap_Allocate_aligned( 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. */ + /* 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 @@ -172,7 +227,7 @@ void *_Heap_Allocate_aligned( _HAssert(_Heap_Is_aligned_ptr((void*)aligned_user_addr, alignment)); - (void)_Heap_Block_allocate(the_heap, the_block, alloc_size); + the_block = block_allocate(the_heap, the_block, alloc_size); stats->searches += search_count + 1; stats->allocs += 1; |