From 7c54cca339e991affffad7d41dbcc1a94b2fba60 Mon Sep 17 00:00:00 2001
From: highmtworks <1973003+highmtworks@users.noreply.github.com>
Date: Sat, 16 Jan 2021 12:32:57 +0900
Subject: [PATCH 1/2] Add a test case for a high tag with three octets

---
 test/index.js | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/test/index.js b/test/index.js
index 91fda28..3f68dcc 100644
--- a/test/index.js
+++ b/test/index.js
@@ -50,6 +50,18 @@ test('decode: tagCode 50 (extended tag / aka high tag)', (t) => {
   );
 });
 
+test('decode: tagCode 257 (extended tag / aka high tag with three octets)', (t) => {
+  t.deepEqual(
+    asn1Tree.decode(b(tag(CLS_CONTEXT_SPECIFIC, FORM_PRIMITIVE, 31), 130, 1, 3, f(3))),
+    {
+      cls: CLS_CONTEXT_SPECIFIC,
+      form: FORM_PRIMITIVE,
+      tagCode: 257,
+      value: f(3)
+    }
+  );
+});
+
 test('decode: primitive: element with length 0', (t) => {
   t.deepEqual(
     asn1Tree.decode(b(tag(CLS_UNIVERSAL, FORM_PRIMITIVE, TAG_NULL), 0)),

From 987c1f97466d1638b36698b6a4419366b8666860 Mon Sep 17 00:00:00 2001
From: highmtworks <1973003+highmtworks@users.noreply.github.com>
Date: Sat, 16 Jan 2021 12:40:04 +0900
Subject: [PATCH 2/2] Fix high tag number decoding

---
 index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/index.js b/index.js
index 8a9af47..4c9a0a6 100644
--- a/index.js
+++ b/index.js
@@ -17,7 +17,7 @@ function decode(buffer) {
     do {
       byte = buffer.readUInt8(bytesRead);
       bytesRead += 1;
-      tagCode = (tagCode << 8) | (byte & 0x7f);
+      tagCode = (tagCode << 7) | (byte & 0x7f);
     } while (byte & 0x80);
   }