Merge pull request #1978 from mikecat/use-bigint-for-varint

Use BigInt for encoding/decoding VarInt

Author: jg42526

src/core/operations/VarIntDecode.mjs

@@ -24,7 +24,7 @@ class VarIntDecode extends Operation {
         this.description = "Decodes a VarInt encoded integer. VarInt is an efficient way of encoding variable length integers and is commonly used with Protobuf.";
         this.infoURL = "https://developers.google.com/protocol-buffers/docs/encoding#varints";
         this.inputType = "byteArray";
-        this.outputType = "number";
+        this.outputType = "string";
         this.args = [];
     }
 
@@ -35,7 +35,18 @@ class VarIntDecode extends Operation {
      */
     run(input, args) {
         try {
-            return Protobuf.varIntDecode(input);
+            if (typeof BigInt === "function") {
+                let result = BigInt(0);
+                let offset = BigInt(0);
+                for (let i = 0; i < input.length; i++) {
+                    result |= BigInt(input[i] & 0x7f) << offset;
+                    if (!(input[i] & 0x80)) break;
+                    offset += BigInt(7);
+                }
+                return result.toString();
+            } else {
+                return Protobuf.varIntDecode(input).toString();
+            }
         } catch (err) {
             throw new OperationError(err);
         }

src/core/operations/VarIntEncode.mjs

@@ -23,19 +23,31 @@ class VarIntEncode extends Operation {
         this.module = "Default";
         this.description = "Encodes a Vn integer as a VarInt. VarInt is an efficient way of encoding variable length integers and is commonly used with Protobuf.";
         this.infoURL = "https://developers.google.com/protocol-buffers/docs/encoding#varints";
-        this.inputType = "number";
+        this.inputType = "string";
         this.outputType = "byteArray";
         this.args = [];
     }
 
     /**
-     * @param {number} input
+     * @param {string} input
      * @param {Object[]} args
      * @returns {byteArray}
      */
     run(input, args) {
         try {
-            return Protobuf.varIntEncode(input);
+            if (typeof BigInt === "function") {
+                let value = BigInt(input);
+                if (value < 0) throw new OperationError("Negative values cannot be represented as VarInt");
+                const result = [];
+                while (value >= 0x80) {
+                    result.push(Number(value & BigInt(0x7f)) | 0x80);
+                    value >>= BigInt(7);
+                }
+                result.push(Number(value));
+                return result;
+            } else {
+                return Protobuf.varIntEncode(Number(input));
+            }
         } catch (err) {
             throw new OperationError(err);
         }