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typed arrays: copy Buffer in typed array constructor

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Convert the Buffer to an ArrayBuffer. The typed_array.buffer property
should be an ArrayBuffer to avoid confusion: a Buffer doesn't have a
byteLength property and more importantly, its slice() method works
subtly different.

That means that before this commit:

  var buf = new Buffer(1);
  var arr = new Int8Array(buf);
  assert.equal(arr.buffer, buf);
  assert(arr.buffer instanceof Buffer);

And now:

  var buf = new Buffer(1);
  var arr = new Int8Array(buf);
  assert.notEqual(arr.buffer, buf);
  assert(arr.buffer instanceof ArrayBuffer);
This commit is contained in:
Ben Noordhuis
2013-02-10 21:28:11 +01:00
parent fe103357ae
commit 5a9d30bb86
2 changed files with 30 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
src/v8_typed_array.cc
View File

@@ -251,9 +251,7 @@ class TypedArray {
unsigned int length = 0;
unsigned int byte_offset = 0;
// [m1k3] added support for Buffer constructor
if (node::Buffer::HasInstance(args[0])
|| ArrayBuffer::HasInstance(args[0])) { // ArrayBuffer constructor.
if (ArrayBuffer::HasInstance(args[0])) { // ArrayBuffer constructor.
buffer = v8::Local<v8::Object>::Cast(args[0]);
size_t buflen =
buffer->GetIndexedPropertiesExternalArrayDataLength();

60
test/simple/test-typed-arrays.js
View File

@@ -52,29 +52,11 @@ var assert = require('assert');
assert.equal(Object.prototype.toString.call(obj), '[object DataView]');
});
// initialize a zero-filled buffer
var buffer = new Buffer(16);
buffer.fill(0);
// only one of these instantiations should succeed, as the other ones will be
// unaligned
var errors = 0;
var offset;
for (var i = 0; i < 8; i++) {
try {
new Float64Array(buffer, i);
offset = i;
} catch (e) {
errors += 1;
}
}
assert.equal(errors, 7);
var uint8 = new Uint8Array(buffer, offset);
var uint16 = new Uint16Array(buffer, offset);
var uint16slice = new Uint16Array(buffer, offset + 2, 2);
var uint32 = new Uint32Array(buffer, offset);
var buffer = new ArrayBuffer(16);
var uint8 = new Uint8Array(buffer);
var uint16 = new Uint16Array(buffer);
var uint16slice = new Uint16Array(buffer, 2, 2);
var uint32 = new Uint32Array(buffer);
assert.equal(uint8.BYTES_PER_ELEMENT, 1);
assert.equal(uint16.BYTES_PER_ELEMENT, 2);
@@ -82,14 +64,14 @@ assert.equal(uint16slice.BYTES_PER_ELEMENT, 2);
assert.equal(uint32.BYTES_PER_ELEMENT, 4);
// now change the underlying buffer
buffer[offset ] = 0x08;
buffer[offset + 1] = 0x09;
buffer[offset + 2] = 0x0a;
buffer[offset + 3] = 0x0b;
buffer[offset + 4] = 0x0c;
buffer[offset + 5] = 0x0d;
buffer[offset + 6] = 0x0e;
buffer[offset + 7] = 0x0f;
buffer[0] = 0x08;
buffer[1] = 0x09;
buffer[2] = 0x0a;
buffer[3] = 0x0b;
buffer[4] = 0x0c;
buffer[5] = 0x0d;
buffer[6] = 0x0e;
buffer[7] = 0x0f;
/*
This is what we expect the variables to look like at this point (on
@@ -202,6 +184,22 @@ assert.throws(function() {
assert.equal(view.getUint16(0), 1);
})();
(function() {
// Typed array should make a copy of the buffer object, i.e. it's not shared.
var b = new Buffer([0]);
var a = new Uint8Array(b);
assert.notEqual(a.buffer, b);
assert.equal(a[0], 0);
assert.equal(b[0], 0);
a[0] = 1;
assert.equal(a[0], 1);
assert.equal(b[0], 0);
a[0] = 0;
b[0] = 1;
assert.equal(a[0], 0);
assert.equal(b[0], 1);
})();
(function() {
// Backing store should not be shared.
var a = new Uint8Array(1);