make a note of data structure for sanity purposes if code is read years later

1 files changed, 8 insertions, 0 deletions

diff --git a/js/png.js b/js/png.js
index df9960c..e9b326e 100644
--- a/js/png.js
+++ b/js/png.js
@@ -60,6 +60,14 @@ var crc32 = function(u8){
 var signature = new Uint8Array([137, 80, 78, 71, 13, 10, 26, 10])
 var te, td
 
+// decodes chunks in png
+// see http://www.w3.org/TR/PNG/#5Chunk-layout
+// returns something like
+// [{length: Number,
+//   type: String[4],
+//   crc: Number,
+//   data: Uint8Array[]  // optional
+// }, ...]
 var decode = function(buf, err){
   var u8a = new Uint8Array(buf)
   var dv = new DataView(buf)