lib: add swap64 (was introduced in node 6.3.0)

news: https://nodejs.org/en/blog/release/v6.3.0/
PR: nodejs/node#7157

Author: itu2n1i8w

index.js

@@ -542,6 +542,20 @@ Buffer.prototype.swap32 = function swap32 () {
   return this
 }
 
+Buffer.prototype.swap64 = function swap64 () {
+  var len = this.length
+  if (len % 8 !== 0) {
+    throw new RangeError('Buffer size must be a multiple of 64-bits')
+  }
+  for (var i = 0; i < len; i += 8) {
+    swap(this, i, i + 7)
+    swap(this, i + 1, i + 6)
+    swap(this, i + 2, i + 5)
+    swap(this, i + 3, i + 4)
+  }
+  return this
+}
+
 Buffer.prototype.toString = function toString () {
   var length = this.length | 0
   if (length === 0) return ''

test/node/test-buffer-swap.js

@@ -5,59 +5,137 @@ if (Buffer.TYPED_ARRAY_SUPPORT) return;
 
 var assert = require('assert');
 
-var buf = Buffer.from([0x1, 0x2, 0x3, 0x4]);
+// Test buffers small enough to use the JS implementation
+const buf = Buffer.from([0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
+                         0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10]);
 
 assert.strictEqual(buf, buf.swap16());
-assert.deepStrictEqual(buf, Buffer.from([0x2, 0x1, 0x4, 0x3]));
+assert.deepStrictEqual(buf, Buffer.from([0x02, 0x01, 0x04, 0x03, 0x06, 0x05,
+                                         0x08, 0x07, 0x0a, 0x09, 0x0c, 0x0b,
+                                         0x0e, 0x0d, 0x10, 0x0f]));
+buf.swap16(); // restore
 
 assert.strictEqual(buf, buf.swap32());
-assert.deepStrictEqual(buf, Buffer.from([0x3, 0x4, 0x1, 0x2]));
-
-var buf_array = [];
-for (var i = 1; i < 33; i++)
-  buf_array.push(i);
-var buf2 = Buffer.from(buf_array);
-buf2.swap32();
-assert.deepStrictEqual(buf2,
-    Buffer.from([0x04, 0x03, 0x02, 0x01, 0x08, 0x07, 0x06, 0x05, 0x0c,
-                 0x0b, 0x0a, 0x09, 0x10, 0x0f, 0x0e, 0x0d, 0x14, 0x13,
-                 0x12, 0x11, 0x18, 0x17, 0x16, 0x15, 0x1c, 0x1b, 0x1a,
-                 0x19, 0x20, 0x1f, 0x1e, 0x1d]));
-buf2.swap16();
-assert.deepStrictEqual(buf2,
-    Buffer.from([0x03, 0x04, 0x01, 0x02, 0x07, 0x08, 0x05, 0x06, 0x0b,
-                 0x0c, 0x09, 0x0a, 0x0f, 0x10, 0x0d, 0x0e, 0x13, 0x14,
-                 0x11, 0x12, 0x17, 0x18, 0x15, 0x16, 0x1b, 0x1c, 0x19,
-                 0x1a, 0x1f, 0x20, 0x1d, 0x1e]));
+assert.deepStrictEqual(buf, Buffer.from([0x04, 0x03, 0x02, 0x01, 0x08, 0x07,
+                                         0x06, 0x05, 0x0c, 0x0b, 0x0a, 0x09,
+                                         0x10, 0x0f, 0x0e, 0x0d]));
+buf.swap32(); // restore
 
+assert.strictEqual(buf, buf.swap64());
+assert.deepStrictEqual(buf, Buffer.from([0x08, 0x07, 0x06, 0x05, 0x04, 0x03,
+                                         0x02, 0x01, 0x10, 0x0f, 0x0e, 0x0d,
+                                         0x0c, 0x0b, 0x0a, 0x09]));
+
+// Operates in-place
 var buf3 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7]);
 buf3.slice(1, 5).swap32();
 assert.deepStrictEqual(buf3, Buffer.from([0x1, 0x5, 0x4, 0x3, 0x2, 0x6, 0x7]));
 
 buf3.slice(1, 5).swap16();
 assert.deepStrictEqual(buf3, Buffer.from([0x1, 0x4, 0x5, 0x2, 0x3, 0x6, 0x7]));
 
+const buf3_64 = Buffer.from([0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+                             0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10,
+                             0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+                             0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10]);
+buf3_64.slice(2, 18).swap64();
+assert.deepStrictEqual(buf3_64, Buffer.from([0x01, 0x02, 0x0a, 0x09, 0x08, 0x07,
+                                             0x06, 0x05, 0x04, 0x03, 0x02, 0x01,
+                                             0x10, 0x0f, 0x0e, 0x0d, 0x0c, 0x0b,
+                                             0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+                                             0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e,
+                                             0x0f, 0x10]));
+
 // Force use of native code (Buffer size above threshold limit for js impl)
-var buf4 = Buffer.allocUnsafe(1024).fill([0x1, 0x2, 0x3, 0x4]);
-var buf5 = Buffer.allocUnsafe(1024).fill([0x2, 0x1, 0x4, 0x3]);
-var buf6 = Buffer.allocUnsafe(1024)
-                   .fill([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);
-var buf7 = Buffer.allocUnsafe(1024)
-                   .fill([0x4, 0x3, 0x2, 0x1, 0x8, 0x7, 0x6, 0x5]);
+var buf4A = new Uint32Array(256).fill(0x04030201);
+var buf4 = Buffer.from(buf4A.buffer, buf4A.byteOffset);
+var buf5A = new Uint32Array(256).fill(0x03040102);
+var buf5 = Buffer.from(buf5A.buffer, buf5A.byteOffset);
 
 buf4.swap16();
 assert.deepStrictEqual(buf4, buf5);
 
+var buf6A = new Uint32Array(256).fill(0x04030201);
+var buf6 = Buffer.from(buf6A.buffer);
+var bu7A = new Uint32Array(256).fill(0x01020304);
+var buf7 = Buffer.from(bu7A.buffer, bu7A.byteOffset);
+
 buf6.swap32();
 assert.deepStrictEqual(buf6, buf7);
 
 
-var re16 = /Buffer size must be a multiple of 16-bits/;
-var re32 = /Buffer size must be a multiple of 32-bits/;
+var buf8A = new Uint8Array(256 * 8);
+var buf9A = new Uint8Array(256 * 8);
+for (let i = 0; i < buf8A.length; i++) {
+  buf8A[i] = i % 8;
+  buf9A[buf9A.length - i - 1] = i % 8;
+}
+var buf8 = Buffer.from(buf8A.buffer, buf8A.byteOffset);
+var buf9 = Buffer.from(buf9A.buffer, buf9A.byteOffset);
+
+buf8.swap64();
+assert.deepStrictEqual(buf8, buf9);
+
+// Test native code with buffers that are not memory-aligned
+var buf10A = new Uint8Array(256 * 8);
+var buf11A = new Uint8Array(256 * 8 - 2);
+for (let i = 0; i < buf10A.length; i++) {
+  buf10A[i] = i % 2;
+}
+for (let i = 1; i < buf11A.length; i++) {
+  buf11A[buf11A.length - i] = (i + 1) % 2;
+}
+var buf10 = Buffer.from(buf10A.buffer, buf10A.byteOffset);
+// 0|1 0|1 0|1...
+var buf11 = Buffer.from(buf11A.buffer, buf11A.byteOffset);
+// 0|0 1|0 1|0...
+
+buf10.slice(1, buf10.length - 1).swap16();
+assert.deepStrictEqual(buf10.slice(0, buf11.length), buf11);
+
+
+var buf12A = new Uint8Array(256 * 8);
+var buf13A = new Uint8Array(256 * 8 - 4);
+for (let i = 0; i < buf12A.length; i++) {
+  buf12A[i] = i % 4;
+}
+for (let i = 1; i < buf13A.length; i++) {
+  buf13A[buf13A.length - i] = (i + 1) % 4;
+}
+var buf12 = Buffer.from(buf12A.buffer, buf12A.byteOffset);
+// 0|1 2 3 0|1 2 3...
+var buf13 = Buffer.from(buf13A.buffer, buf13A.byteOffset);
+// 0|0 3 2 1|0 3 2...
+
+buf12.slice(1, buf12.length - 3).swap32();
+assert.deepStrictEqual(buf12.slice(0, buf13.length), buf13);
+
+
+var buf14A = new Uint8Array(256 * 8);
+var buf15A = new Uint8Array(256 * 8 - 8);
+for (let i = 0; i < buf14A.length; i++) {
+  buf14A[i] = i % 8;
+}
+for (let i = 1; i < buf15A.length; i++) {
+  buf15A[buf15A.length - i] = (i + 1) % 8;
+}
+var buf14 = Buffer.from(buf14A.buffer, buf14A.byteOffset);
+// 0|1 2 3 4 5 6 7 0|1 2 3 4...
+var buf15 = Buffer.from(buf15A.buffer, buf15A.byteOffset);
+// 0|0 7 6 5 4 3 2 1|0 7 6 5...
+
+buf14.slice(1, buf14.length - 7).swap64();
+assert.deepStrictEqual(buf14.slice(0, buf15.length), buf15);
+
+// Length assertions
+const re16 = /Buffer size must be a multiple of 16-bits/;
+const re32 = /Buffer size must be a multiple of 32-bits/;
+const re64 = /Buffer size must be a multiple of 64-bits/;
 
 assert.throws(() => Buffer.from(buf3).swap16(), re16);
 assert.throws(() => Buffer.alloc(1025).swap16(), re16);
 assert.throws(() => Buffer.from(buf3).swap32(), re32);
 assert.throws(() => buf3.slice(1, 3).swap32(), re32);
 assert.throws(() => Buffer.alloc(1025).swap32(), re32);
-
+assert.throws(() => buf3.slice(1, 3).swap64(), re64);
+assert.throws(() => Buffer.alloc(1025).swap64(), re64);