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heap: Fix edge case of reusing first node
There is an edge case fixed where the whole would be freed and this would make use of a nullptr. Additionally, remove usage of reserved names for vars and add comments on how it works.
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parent
03a8a11933
commit
6a52d44da6
2 changed files with 56 additions and 34 deletions
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@ -29,7 +29,7 @@ static void _heap_create(heap_t *heap, u32 start)
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// Node info is before node address.
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static u32 _heap_alloc(heap_t *heap, u32 size)
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{
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hnode_t *node, *new;
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hnode_t *node, *new_node;
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// Align to cache line size.
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size = ALIGN(size, sizeof(hnode_t));
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@ -49,22 +49,29 @@ static u32 _heap_alloc(heap_t *heap, u32 size)
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node = heap->first;
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while (true)
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{
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// Check if there's available unused node.
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if (!node->used && (size <= node->size))
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{
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// Size and offset of the new unused node.
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u32 new_size = node->size - size;
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new = (hnode_t *)((u32)node + sizeof(hnode_t) + size);
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new_node = (hnode_t *)((u32)node + sizeof(hnode_t) + size);
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// If there's aligned leftover space, create a new node.
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// If there's aligned unused space from the old node,
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// create a new one and set the leftover size.
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if (new_size >= (sizeof(hnode_t) << 2))
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{
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new->size = new_size - sizeof(hnode_t);
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new->used = 0;
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new->next = node->next;
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new->next->prev = new;
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new->prev = node;
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node->next = new;
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new_node->size = new_size - sizeof(hnode_t);
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new_node->used = 0;
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new_node->next = node->next;
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// Check that we are not on first node.
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if (new_node->next)
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new_node->next->prev = new_node;
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new_node->prev = node;
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node->next = new_node;
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}
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else
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else // Unused node size is just enough.
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size += new_size;
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node->size = size;
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@ -72,20 +79,23 @@ static u32 _heap_alloc(heap_t *heap, u32 size)
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return (u32)node + sizeof(hnode_t);
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}
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// No unused node found, try the next one.
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if (node->next)
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node = node->next;
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else
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break;
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}
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new = (hnode_t *)((u32)node + sizeof(hnode_t) + node->size);
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new->used = 1;
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new->size = size;
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new->prev = node;
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new->next = NULL;
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node->next = new;
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// No unused node found, create a new one.
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new_node = (hnode_t *)((u32)node + sizeof(hnode_t) + node->size);
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new_node->used = 1;
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new_node->size = size;
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new_node->prev = node;
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new_node->next = NULL;
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node->next = new_node;
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return (u32)new + sizeof(hnode_t);
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return (u32)new_node + sizeof(hnode_t);
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}
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static void _heap_free(heap_t *heap, u32 addr)
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@ -101,6 +111,7 @@ static void _heap_free(heap_t *heap, u32 addr)
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{
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node->prev->size += node->size + sizeof(hnode_t);
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node->prev->next = node->next;
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if (node->next)
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node->next->prev = node->prev;
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}
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@ -29,7 +29,7 @@ static void _heap_create(heap_t *heap, u32 start)
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// Node info is before node address.
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static u32 _heap_alloc(heap_t *heap, u32 size)
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{
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hnode_t *node, *new;
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hnode_t *node, *new_node;
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// Align to cache line size.
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size = ALIGN(size, sizeof(hnode_t));
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@ -49,22 +49,29 @@ static u32 _heap_alloc(heap_t *heap, u32 size)
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node = heap->first;
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while (true)
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{
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// Check if there's available unused node.
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if (!node->used && (size <= node->size))
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{
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// Size and offset of the new unused node.
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u32 new_size = node->size - size;
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new = (hnode_t *)((u32)node + sizeof(hnode_t) + size);
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new_node = (hnode_t *)((u32)node + sizeof(hnode_t) + size);
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// If there's aligned leftover space, create a new node.
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// If there's aligned unused space from the old node,
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// create a new one and set the leftover size.
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if (new_size >= (sizeof(hnode_t) << 2))
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{
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new->size = new_size - sizeof(hnode_t);
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new->used = 0;
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new->next = node->next;
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new->next->prev = new;
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new->prev = node;
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node->next = new;
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new_node->size = new_size - sizeof(hnode_t);
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new_node->used = 0;
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new_node->next = node->next;
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// Check that we are not on first node.
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if (new_node->next)
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new_node->next->prev = new_node;
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new_node->prev = node;
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node->next = new_node;
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}
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else
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else // Unused node size is just enough.
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size += new_size;
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node->size = size;
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@ -72,20 +79,23 @@ static u32 _heap_alloc(heap_t *heap, u32 size)
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return (u32)node + sizeof(hnode_t);
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}
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// No unused node found, try the next one.
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if (node->next)
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node = node->next;
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else
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break;
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}
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new = (hnode_t *)((u32)node + sizeof(hnode_t) + node->size);
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new->used = 1;
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new->size = size;
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new->prev = node;
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new->next = NULL;
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node->next = new;
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// No unused node found, create a new one.
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new_node = (hnode_t *)((u32)node + sizeof(hnode_t) + node->size);
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new_node->used = 1;
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new_node->size = size;
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new_node->prev = node;
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new_node->next = NULL;
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node->next = new_node;
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return (u32)new + sizeof(hnode_t);
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return (u32)new_node + sizeof(hnode_t);
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}
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static void _heap_free(heap_t *heap, u32 addr)
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@ -101,6 +111,7 @@ static void _heap_free(heap_t *heap, u32 addr)
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{
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node->prev->size += node->size + sizeof(hnode_t);
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node->prev->next = node->next;
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if (node->next)
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node->next->prev = node->prev;
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}
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