add bn support to varint class

lib/varint.js

@@ -31,6 +31,11 @@ Varint.prototype.fromBufferReader = function(br) {
   return this;
 };
 
+Varint.prototype.fromBN = function(bn) {
+  this.buf = BufferWriter().writeVarintBN(bn).concat();
+  return this;
+};
+
 Varint.prototype.fromNumber = function(num) {
   this.buf = BufferWriter().writeVarintNum(num).concat();
   return this;
@@ -40,6 +45,10 @@ Varint.prototype.toBuffer = function() {
   return this.buf;
 };
 
+Varint.prototype.toBN = function() {
+  return BufferReader(this.buf).readVarintBN();
+};
+
 Varint.prototype.toNumber = function() {
   return BufferReader(this.buf).readVarintNum();
 };

test/varint.js

@@ -1,3 +1,4 @@
+var BN = require('../lib/bn');
 var should = require('chai').should();
 var BufferReader = require('../lib/bufferreader');
 var BufferWriter = require('../lib/bufferwriter');
@@ -48,6 +49,15 @@ describe('Varint', function() {
 
   });
 
+  describe('#fromBN', function() {
+    
+    it('should set a number', function() {
+      var varint = Varint().fromNumber(BN(5));
+      varint.toNumber().should.equal(5);
+    });
+
+  });
+
   describe('#fromNumber', function() {
     
     it('should set a number', function() {
@@ -67,6 +77,15 @@ describe('Varint', function() {
 
   });
 
+  describe('#toBN', function() {
+    
+    it('should return a buffer', function() {
+      var varint = Varint(5);
+      varint.toBN().toString().should.equal(BN(5).toString());
+    });
+
+  });
+
   describe('#toNumber', function() {
     
     it('should return a buffer', function() {