lib: fix BN#imuln for negative numbers

indutny · May 28, 2018 · 6a90bcb · 6a90bcb
1 parent 98ac84e
commit 6a90bcb
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Showing 2 changed files with 10 additions and 1 deletion.
diff --git a/lib/bn.js b/lib/bn.js
@@ -1908,6 +1908,9 @@
   };
 
   BN.prototype.imuln = function imuln (num) {
+    var isNegNum = num < 0;
+    if (isNegNum) num = -num;
+
     assert(typeof num === 'number');
     assert(num < 0x4000000);
 
@@ -1928,7 +1931,7 @@
       this.length++;
     }
 
-    return this;
+    return isNegNum ? this.ineg() : this;
   };
 
   BN.prototype.muln = function muln (num) {

diff --git a/test/arithmetic-test.js b/test/arithmetic-test.js
@@ -290,6 +290,12 @@ describe('BN.js/Arithmetic', function () {
         new BN(0).imuln(0x4000000);
       }, /^Error: Assertion failed$/);
     });
+
+    it('should negate number if number is negative', function () {
+      var a = new BN('dead', 16);
+
+      assert.equal(a.muln(-1).toString(16), a.neg().toString(16));
+    });
   });
 
   describe('.pow()', function () {