mempool utility function to get the element at an index BLI_mempool_findelem(), not used yet.

2 files changed, 21 insertions, 2 deletions

diff --git a/source/blender/blenlib/BLI_mempool.h b/source/blender/blenlib/BLI_mempool.h
index f98919fadd3..a46ba78aef0 100644
--- a/source/blender/blenlib/BLI_mempool.h
+++ b/source/blender/blenlib/BLI_mempool.h
@@ -55,6 +55,7 @@ void *BLI_mempool_calloc(BLI_mempool *pool);
 void BLI_mempool_free(BLI_mempool *pool, void *addr);
 void BLI_mempool_destroy(BLI_mempool *pool);
 int BLI_mempool_count(BLI_mempool *pool);
+void *BLI_mempool_findelem(BLI_mempool *pool, const int index);
 
 /** iteration stuff.  note: this may easy to produce bugs with **/
 /*private structure*/
diff --git a/source/blender/blenlib/intern/BLI_mempool.c b/source/blender/blenlib/intern/BLI_mempool.c
index 19ae89da8ea..f8da524d097 100644
--- a/source/blender/blenlib/intern/BLI_mempool.c
+++ b/source/blender/blenlib/intern/BLI_mempool.c
@@ -68,8 +68,9 @@ typedef struct BLI_mempool_chunk {
 
 struct BLI_mempool {
 	struct ListBase chunks;
-	int esize, csize, pchunk;        /* size of elements and chunks in bytes
-	                                  * and number of elements per chunk*/
+	int esize;         /* element size in bytes */
+	int csize;         /* chunk size in bytes */
+	int pchunk;        /* number of elements per chunk */
 	short use_sysmalloc, allow_iter;
 	/* keeps aligned to 16 bits */
 
@@ -240,6 +241,23 @@ void BLI_mempool_free(BLI_mempool *pool, void *addr)
 	}
 }
 
+void *BLI_mempool_findelem(BLI_mempool *pool, const int index)
+{
+	if ((index >= 0) && (index < pool->totused)) {
+		BLI_mempool_chunk *mpchunk;
+		int i= 0;
+
+		for (mpchunk = pool->chunks.first; mpchunk; mpchunk = mpchunk->next) {
+			if (index < i + pool->pchunk) {
+				return ((char *)mpchunk->data) + (pool->esize * (index - i));
+			}
+			i += pool->pchunk;
+		}
+	}
+
+	return NULL;
+}
+
 void BLI_mempool_iternew(BLI_mempool *pool, BLI_mempool_iter *iter)
 {
 	if (!pool->allow_iter) {