Implemented lfsr_btree_split, a shortcut for pop+push+push

Another straightforward exercise of making sure the pending attributes are setup correctly. If you think this isn't worth its own function, consider how much overhead the 3x commits for pop+push+push would add, especially for large-prog devices. Worst case this can be dropped in the future.
2023-03-13 14:18:22 -05:00
parent dd5af724fd
commit 15e27f92af
2 changed files with 430 additions and 10 deletions
@@ -4225,6 +4225,74 @@ static int lfsr_btree_pop(lfs_t *lfs, lfsr_btree_t *btree, lfs_size_t id) {
    }
 }

+// lfsr_btree_split can be done with a pop+push+push, but this function
+// does all this in one commit, which is much more efficient
+static int lfsr_btree_split(lfs_t *lfs, lfsr_btree_t *btree,
+        lfs_size_t id,
+        lfsr_tag_t tag1, lfs_size_t weight1,
+        const void *buffer1, lfs_size_t size1,
+        lfsr_tag_t tag2, lfs_size_t weight2,
+        const void *buffer2, lfs_size_t size2) {
+    LFS_ASSERT(id < btree->weight);
+
+    // inlined btree, need to expand into an rbyd
+    if (btree->tag) {
+        lfsr_rbyd_t rbyd;
+        int err = lfsr_rbyd_alloc(lfs, &rbyd, 1);
+        if (err) {
+            return err;
+        }
+
+        // commit our entries
+        err = lfsr_rbyd_commit(lfs, &rbyd,
+                LFSR_ATTR(GROW, 0, NULL, weight1,
+                LFSR_ATTR(MKBRANCH, 0+weight1-1, NULL, 0,
+                LFSR_ATTR_(tag1, 0+weight1-1,
+                    buffer1, size1,
+                LFSR_ATTR(GROW, weight1, NULL, weight2,
+                LFSR_ATTR(MKBRANCH, weight1+weight2-1, NULL, 0,
+                LFSR_ATTR_(tag2, weight1+weight2-1,
+                    buffer2, size2,
+                NULL)))))));
+        if (err) {
+            return err;
+        }
+
+        btree->tag = 0;
+        btree->weight = rbyd.weight;
+        btree->u.trunk.block = rbyd.block;
+        btree->u.trunk.limit = rbyd.off;
+        return 0;
+
+    // a normal btree
+    } else {
+        // lookup in which leaf our id resides
+        lfsr_rbyd_t rbyd;
+        lfs_ssize_t rid;
+        lfs_size_t rweight;
+        lfs_ssize_t size = lfsr_btree_lookup(lfs, btree, id,
+                NULL, NULL, &rbyd, &rid, &rweight, NULL, 0);
+        if (size < 0) {
+            return size;
+        }
+
+        // commit our id into the tree, letting lfsr_btree_commit take care
+        // of the rest
+        return lfsr_btree_commit(lfs, btree, id, &rbyd,
+                LFSR_ATTR(SHRINK, rid-(rweight-1), NULL, rweight,
+                LFSR_ATTR(GROW, rid-(rweight-1), NULL, weight1,
+                LFSR_ATTR(MKBRANCH, rid-(rweight-1)+weight1-1, NULL, 0,
+                LFSR_ATTR_(tag1, rid-(rweight-1)+weight1-1,
+                    buffer1, size1,
+                LFSR_ATTR(GROW, rid-(rweight-1)+weight1, NULL, weight2,
+                LFSR_ATTR(MKBRANCH, rid-(rweight-1)+weight1+weight2-1, NULL, 0,
+                LFSR_ATTR_(tag2, rid-(rweight-1)+weight1+weight2-1,
+                    buffer2, size2,
+                NULL))))))));
+    }
+}
+
+