add new test for u256 mul

assembly/__tests__/u256.spec.ts

@@ -1,4 +1,4 @@
-import { u128 } from '../integer';
+import { u128 } from '../integer/u128';
 import { u256 } from '../integer/u256';
 
 describe("String Conversion", () => {
@@ -368,23 +368,25 @@ describe("Basic Operations", () => {
     expect(b * a).toStrictEqual(r);
   });
 
-  it("Should multiply two random u256 numbers", () => {
-    let i = 0;
-    while(i< 20) {
-      const randa = <u64>Math.trunc(Math.random() * 0xFFFF)
-      const a = u256.from(randa);
-      const randb = <u64>Math.trunc(Math.random() * 0xFFFF)
-      const b = u256.from(randb);
-      const r = new u256(randa * randb);
+  it("Should multiply two u256 numbers - 2", () => {
+    var a = u256.from(11);
+    var b = new u256(0, 2);
+    var r = new u256(0, 22);
 
-      expect(a * b).toStrictEqual(r);
-      expect(b * a).toStrictEqual(r);
-      i++;
-    }
+    expect(a * b).toStrictEqual(r);
+    expect(b * a).toStrictEqual(r);
   });
 
+  it("Should multiply two u256 numbers - 3", () => {
+    var a = new u256(0, 3);
+    var b = new u256(0, 0,3);
+    var r = new u256(0, 0,0,9);
 
-  it("Should multiply two u256 numbers - 2", () => {
+    expect(a * b).toStrictEqual(r);
+    expect(b * a).toStrictEqual(r);
+  });
+
+  it("Should multiply two u256 numbers - 4", () => {
     var a = u256.from(new u128(14083847773837265618, 6692605942));
     var b = u256.from(new u128(18444665141527514289, 5354084802));
     var r = new u256(5659639222556316466, 4474720309748468391, 17386035696907167262, 1);
@@ -419,4 +421,22 @@ describe("Basic Operations", () => {
     expect(a * a).toStrictEqual(new u256(1, 0, 2));
   });
 
+  it("Should multiply two u256 numbers with overflow - 3", () => {
+    var a = new u256(6, 0, 0, 420);
+    var b = new u256(0, 7, 0, 0);
+    var r = new u256(0, 42, 0, 0);
+
+    expect(a * b).toStrictEqual(r);
+    expect(b * a).toStrictEqual(r);
+  });
+
+  it("Should multiply two u256 numbers with overflow - 3", () => {
+    var a = new u256(2, 666, 666, 666);
+    var b = new u256(0, 0, 0, 3);
+    var r = new u256(0, 0, 0, 6);
+
+    expect(a * b).toStrictEqual(r);
+    expect(b * a).toStrictEqual(r);
+  });
+
 });

assembly/globals.ts

@@ -125,6 +125,7 @@ export function __uadd64(x: u64, y: u64, carry: u64 = 0): u64 {
 
 }
 
+// u256 * u256 => u256 implementation based on https://github.com/holiman/uint256
 // @ts-ignore: decorator
 @global
 export function __mul256(x0: u64, x1: u64, x2: u64, x3: u64, y0: u64, y1: u64, y2: u64, y3: u64): u256 {