From 5959b149a60877d876b42f24cd3ca81243186e9b Mon Sep 17 00:00:00 2001
From: DwarfiusDan <daniel.prihodko@facepunchstudios.com>
Date: Wed, 22 Jan 2025 11:40:29 +0000
Subject: [PATCH] Update: add VarInt U64 buffer read&write utility funcs Allows
 to avoid interacting with a stream and it's bookkeeping. Tests: Used as part
 of server demo playback

---
 .../ProtocolParser/ProtocolParserVarInt.cs    | 60 +++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/CodeGenerator/ProtocolParser/ProtocolParserVarInt.cs b/CodeGenerator/ProtocolParser/ProtocolParserVarInt.cs
index 3f4dbe5..b660b04 100644
--- a/CodeGenerator/ProtocolParser/ProtocolParserVarInt.cs
+++ b/CodeGenerator/ProtocolParser/ProtocolParserVarInt.cs
@@ -266,6 +266,41 @@ public static ulong ReadUInt64(Stream stream)
             throw new ProtocolBufferException("Got larger VarInt than 64 bit unsigned");
         }
 
+        /// <summary>
+        /// Unsigned VarInt format
+        /// </summary>
+        public static ulong ReadUInt64(byte[] array, int pos, out int length)
+        {
+            ulong val = 0;
+            length = 0;
+
+            for (byte n = 0; n < 10; n++)
+            {
+                length++;
+
+                if(pos >= array.Length)
+                {
+                    break;
+                }
+
+                byte b = array[pos++];
+                if (b < 0)
+                    throw new IOException("Stream ended too early");
+
+                //Check that it fits in 64 bits
+                if ((n == 9) && (b & 0xFE) != 0)
+                    throw new ProtocolBufferException("Got larger VarInt than 64 bit unsigned");
+                //End of check
+
+                if ((b & 0x80) == 0)
+                    return val | (ulong) b << (7 * n);
+
+                val |= (ulong) (b & 0x7F) << (7 * n);
+            }
+
+            throw new ProtocolBufferException("Got larger VarInt than 64 bit unsigned");
+        }
+
         /// <summary>
         /// Unsigned VarInt format
         /// </summary>
@@ -289,6 +324,31 @@ public static void WriteUInt64(Stream stream, ulong val)
             }
         }
 
+        /// <summary>
+        /// Unsigned VarInt format
+        /// </summary>
+        public static int WriteUInt64(ulong val, byte[] buffer, int pos)
+        {
+            int len = 0;
+            while (true)
+            {
+                len++;
+                byte b = (byte)(val & 0x7F);
+                val = val >> 7;
+                if (val == 0)
+                {
+                    buffer[pos] = b;
+                    break;
+                }
+                else
+                {
+                    b |= 0x80;
+                    buffer[pos++] = b;
+                }
+            }
+            return len;
+        }
+
         #endregion
 
         #region Varint: bool