1 files changed, 20 insertions, 2 deletions
diff --git a/src/parseTools.js b/src/parseTools.js
index 071ed090..b401c1a5 100644
--- a/src/parseTools.js
+++ b/src/parseTools.js
@@ -602,6 +602,22 @@ function parseArbitraryInt(str, bits) {
     }
   }
 
+  function mul2(v) { // v *= 2
+    for (var i = v.length-1; i >= 0; i--) {
+      var d = v[i]*2;
+      r = d >= 10;
+      v[i] = d%10;
+      var j = i-1;
+      if (r) {
+        if (j < 0) {
+          v.unshift(1);
+          break;
+        }
+        v[j] += 0.5; // will be multiplied
+      }
+    }
+  }
+
   function subtract(v, w) { // v -= w. we assume v >= w
     while (v.length > w.length) w.splice(0, 0, 0);
     for (var i = 0; i < v.length; i++) {
@@ -631,9 +647,11 @@ function parseArbitraryInt(str, bits) {
 
   if (str[0] == '-') {
     // twos-complement is needed
-    assert(bits == 64, "we only support 64-bit two's complement so far");
     str = str.substr(1);
-    v = str2vec('18446744073709551616'); // 2^64
+    v = str2vec('1');
+    for (var i = 0; i < bits; i++) {
+      mul2(v);
+    }
     subtract(v, str2vec(str));
   } else {
     v = str2vec(str);