format: Move commitgraph and packfile here

1 files changed, 21 insertions, 0 deletions

diff --git a/format/commitgraph/read/layer_pos.go b/format/commitgraph/read/layer_pos.go
new file mode 100644
index 00000000..7b87b381
--- /dev/null
+++ b/format/commitgraph/read/layer_pos.go
@@ -0,0 +1,21 @@
+package read
+
+import "codeberg.org/lindenii/furgit/internal/intconv"
+
+func (reader *Reader) layerByPosition(pos Position) (*layer, error) {
+	graphIdx, err := intconv.Uint64ToInt(uint64(pos.Graph))
+	if err != nil {
+		return nil, err
+	}
+
+	if graphIdx < 0 || graphIdx >= len(reader.layers) {
+		return nil, &PositionOutOfRangeError{Pos: pos}
+	}
+
+	layer := &reader.layers[graphIdx]
+	if pos.Index >= layer.numCommits {
+		return nil, &PositionOutOfRangeError{Pos: pos}
+	}
+
+	return layer, nil
+}