tor-browser

arraybuffer-transfer.js (1707B)

---

// |jit-test| heavy
const gb = 1 * 1024 * 1024 * 1024;

const smallByteLength = 1024;
const largeByteLength = 4 * gb;

// Fast alternative to |assertEq| to avoid a slow VM-call.
// Should only be used when looping over the TypedArray contents to avoid
// unnecessary test slowdowns.
function assertEqNum(e, a) {
 if (e !== a) {
   assertEq(e, a);
 }
}

{
 let smallBuffer = new ArrayBuffer(smallByteLength);

 let i8 = new Uint8Array(smallBuffer);
 for (let i = 0; i < smallByteLength; ++i) {
   assertEqNum(i8[i], 0);
   i8[i] = i;
 }

 assertEq(smallBuffer.byteLength, smallByteLength);
 assertEq(smallBuffer.detached, false);

 // Copy from a small into a large buffer.
 let largeBuffer = smallBuffer.transfer(largeByteLength);

 assertEq(smallBuffer.byteLength, 0);
 assertEq(smallBuffer.detached, true);

 assertEq(largeBuffer.byteLength, largeByteLength);
 assertEq(largeBuffer.detached, false);

 i8 = new Uint8Array(largeBuffer);
 for (let i = 0; i < smallByteLength; ++i) {
   assertEqNum(i8[i], i & 0xff);
 }

 // Test the first 100 new bytes.
 for (let i = smallByteLength; i < smallByteLength + 100; ++i) {
   assertEqNum(i8[i], 0);
 }

 // And the last 100 new bytes.
 for (let i = largeByteLength - 100; i < largeByteLength; ++i) {
   assertEqNum(i8[i], 0);
 }

 // Copy back from a large into a small buffer.
 smallBuffer = largeBuffer.transfer(smallByteLength);

 assertEq(largeBuffer.byteLength, 0);
 assertEq(largeBuffer.detached, true);

 assertEq(smallBuffer.byteLength, smallByteLength);
 assertEq(smallBuffer.detached, false);

 i8 = new Uint8Array(smallBuffer);
 for (let i = 0; i < smallByteLength; ++i) {
   assertEqNum(i8[i], i & 0xff);
 }
}