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buffer: add swap16() and swap32() methods
Adds Buffer.prototype.swap16() and Buffer.prototype.swap32() methods that mutate the Buffer instance in-place by swapping the 16-bit and 32-bit byte-order. Example: ```js const buf = Buffer([0x1, 0x2, 0x3, 0x4]); buf.swap16(); console.log(buf); // prints Buffer(0x2, 0x1, 0x4, 0x3); buf.swap32(); console.log(buf); // prints Buffer(0x3, 0x4, 0x1, 0x2); ``` PR-URL: #5724 Reviewed-By: Trevor Norris <trev.norris@gmail.com>
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'use strict'; | ||
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const common = require('../common.js'); | ||
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const bench = common.createBenchmark(main, { | ||
method: ['swap16', 'swap32', 'htons', 'htonl'], | ||
len: [4, 64, 512, 768, 1024, 1536, 2056, 4096, 8192], | ||
n: [1e6] | ||
}); | ||
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// The htons and htonl methods below are used to benchmark the | ||
// performance difference between doing the byteswap in pure | ||
// javascript regardless of Buffer size as opposed to dropping | ||
// down to the native layer for larger Buffer sizes. | ||
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Buffer.prototype.htons = function htons() { | ||
if (this.length % 2 !== 0) | ||
throw new RangeError(); | ||
for (var i = 0, n = 0; i < this.length; i += 2) { | ||
n = this[i]; | ||
this[i] = this[i + 1]; | ||
this[i + 1] = n; | ||
} | ||
return this; | ||
}; | ||
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Buffer.prototype.htonl = function htonl() { | ||
if (this.length % 2 !== 0) | ||
throw new RangeError(); | ||
for (var i = 0, n = 0; i < this.length; i += 4) { | ||
n = this[i]; | ||
this[i] = this[i + 3]; | ||
this[i + 3] = n; | ||
n = this[i + 1]; | ||
this[i + 1] = this[i + 2]; | ||
this[i + 2] = n; | ||
} | ||
return this; | ||
}; | ||
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function createBuffer(len) { | ||
const buf = Buffer.allocUnsafe(len); | ||
for (var i = 1; i <= len; i++) | ||
buf[i - 1] = i; | ||
return buf; | ||
} | ||
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function bufferSwap(n, buf, method) { | ||
for (var i = 1; i <= n; i++) | ||
buf[method](); | ||
} | ||
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function main(conf) { | ||
const method = conf.method; | ||
const len = conf.len | 0; | ||
const n = conf.n | 0; | ||
const buf = createBuffer(len); | ||
bench.start(); | ||
bufferSwap(n, buf, method); | ||
bench.end(n); | ||
} |
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'use strict'; | ||
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require('../common'); | ||
const assert = require('assert'); | ||
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const buf = Buffer.from([0x1, 0x2, 0x3, 0x4]); | ||
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assert.strictEqual(buf, buf.swap16()); | ||
assert.deepStrictEqual(buf, Buffer.from([0x2, 0x1, 0x4, 0x3])); | ||
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assert.strictEqual(buf, buf.swap32()); | ||
assert.deepStrictEqual(buf, Buffer.from([0x3, 0x4, 0x1, 0x2])); | ||
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const buf_array = []; | ||
for (var i = 1; i < 33; i++) | ||
buf_array.push(i); | ||
const 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])); | ||
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const 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])); | ||
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buf3.slice(1, 5).swap16(); | ||
assert.deepStrictEqual(buf3, Buffer.from([0x1, 0x4, 0x5, 0x2, 0x3, 0x6, 0x7])); | ||
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// Force use of native code (Buffer size above threshold limit for js impl) | ||
const buf4 = Buffer.allocUnsafe(1024).fill([0x1, 0x2, 0x3, 0x4]); | ||
const buf5 = Buffer.allocUnsafe(1024).fill([0x2, 0x1, 0x4, 0x3]); | ||
const buf6 = Buffer.allocUnsafe(1024) | ||
.fill([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]); | ||
const buf7 = Buffer.allocUnsafe(1024) | ||
.fill([0x4, 0x3, 0x2, 0x1, 0x8, 0x7, 0x6, 0x5]); | ||
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buf4.swap16(); | ||
assert.deepStrictEqual(buf4, buf5); | ||
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buf6.swap32(); | ||
assert.deepStrictEqual(buf6, buf7); | ||
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const re16 = /Buffer size must be a multiple of 16-bits/; | ||
const re32 = /Buffer size must be a multiple of 32-bits/; | ||
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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); |