mufs: implement mufs_get_index() to select the index bits from the va at a specific depth

source/fs/mufs/tree.c

@@ -27,6 +27,18 @@ void mufs_del_tree(struct mufs_tree *tree)
 	free(tree);
 }
 
+static size_t mufs_get_index(struct mufs *fs, uint32_t va, uint8_t depth)
+{
+	size_t i;
+
+	for (i = 0; i < depth; ++i)
+		va >>= fs->log2_nentries;
+
+	va &= BITS(0, fs->log2_nentries);
+
+	return va;
+}
+
 static int mufs_do_lookup(struct mufs *fs, uint32_t *page,
 	uint32_t base, uint8_t depth, uint32_t va, uint32_t new_page,
 	unsigned alloc)
@@ -38,15 +50,16 @@ static int mufs_do_lookup(struct mufs *fs, uint32_t *page,
 	if (!base)
 		return -1;
 
-	if (!depth) {
+	if (depth == 0) {
 		*page = base;
 		return 0;
 	}
 
-	index = va & ((1 << ((depth - 1) * fs->log2_nentries)) - 1);
+	base <<= dev->log2_block_size;
+	index = mufs_get_index(fs, va, depth);
+	base += index * sizeof entry;
 
-	if (flash_read(dev, (base << dev->log2_block_size) + index * sizeof entry,
-		&entry, sizeof entry) == 0)
+	if (flash_read(dev, base, &entry, sizeof entry) == 0)
 		return -1;
 
 	if (!entry) {
@@ -58,8 +71,7 @@ static int mufs_do_lookup(struct mufs *fs, uint32_t *page,
 			}
 		}
 
-		if (flash_write(dev, (base << dev->log2_block_size) +
-			index * sizeof entry, &entry, sizeof entry) == 0)
+		if (flash_write(dev, base, &entry, sizeof entry) == 0)
 			return -1;
 
 		if (flash_sync(dev) < 0)
@@ -104,27 +116,27 @@ static int mufs_do_free_page(struct mufs *fs, uint32_t base,
 	uint32_t entry;
 	size_t index;
 
-	if (base == 0)
+	if (!base)
 		return -1;
 
-	if (!depth) {
+	if (depth == 0) {
 		if (free_page)
 			mufs_free_block(fs, base);
 
 		return 0;
 	}
 
-	index = va & ((1 << (fs->log2_nentries * (depth - 1))) - 1);
+	base <<= dev->log2_block_size;
+	index = mufs_get_index(fs, va, depth);
+	base += index * sizeof entry;
 
-	if (flash_read(fs->dev, (base << dev->log2_block_size) + index *
-		sizeof entry, &entry, sizeof entry) == 0)
+	if (flash_read(fs->dev, base, &entry, sizeof entry) == 0)
 		return -1;
 
 	if (mufs_do_free_page(fs, entry, depth - 1, va, free_page) < 0)
 		return -1;
 
-	if (flash_write0(fs->dev, (base << dev->log2_block_size) + index *
-		sizeof entry, sizeof entry) == 0)
+	if (flash_write0(fs->dev, base, sizeof entry) == 0)
 		return -1;
 
 	return flash_sync(fs->dev);