time-to-botec/js/node_modules/@stdlib/buffer/from-arraybuffer/lib/main.js

106 lines
3.6 KiB
JavaScript
Raw Normal View History

/**
* @license Apache-2.0
*
* Copyright (c) 2018 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
'use strict';
// MODULES //
var isArrayBuffer = require( '@stdlib/assert/is-arraybuffer' );
var isNonNegativeInteger = require( '@stdlib/assert/is-nonnegative-integer' ).isPrimitive;
var Buffer = require( './../../ctor' );
var version = require( './node_version.js' );
// MAIN //
/**
* Allocates a buffer from an `ArrayBuffer`.
*
* ## Notes
*
* The behavior of this function varies across Node.js versions due to changes in the underlying Node.js APIs:
*
* - `<6.0.0`: if provided an empty ArrayBuffer, the function returns an empty Buffer which is **not** an ArrayBuffer view.
* - otherwise, the function returns a view of an ArrayBuffer without copying the underlying memory.
*
*
* @param {ArrayBuffer} buf - ArrayBuffer instance
* @param {NonNegativeInteger} [byteOffset=0] - index specifying the location of the first buffer byte
* @param {NonNegativeInteger} [length=buf.byteLength] - number of buffer bytes
* @throws {TypeError} first argument must be an ArrayBuffer
* @throws {TypeError} second argument must be a nonnegative integer
* @throws {RangeError} second argument must not exceed number of bytes in input ArrayBuffer
* @throws {TypeError} last argument must be a nonnegative integer
* @throws {RangeError} last argument must not exceed number of bytes in input ArrayBuffer
* @returns {Buffer} new `Buffer` instance
*
* @example
* var ArrayBuffer = require( '@stdlib/array/buffer' );
* var ab = new ArrayBuffer( 10 );
*
* var buf = fromArrayBuffer( ab );
* // returns <Buffer>
*
* @example
* var ArrayBuffer = require( '@stdlib/array/buffer' );
* var ab = new ArrayBuffer( 10 );
*
* var buf = fromArrayBuffer( ab, 2, 4 );
* // returns <Buffer>
*/
function fromArrayBuffer( buf, byteOffset, length ) {
var offset;
var len;
if ( !isArrayBuffer( buf ) ) {
throw new TypeError( 'invalid argument. First argument must be an ArrayBuffer. Value: `' + buf + '`' );
}
if ( arguments.length > 1 ) {
if ( !isNonNegativeInteger( byteOffset ) ) {
throw new TypeError( 'invalid argument. Second argument must be a nonnegative integer. Value: `' + byteOffset + '`.' );
}
if ( byteOffset > buf.byteLength ) {
throw new RangeError( 'invalid argument. Second argument must not exceed the number of bytes in the input ArrayBuffer. Value: `' + byteOffset + '`.' );
}
offset = byteOffset;
if ( arguments.length > 2 ) {
if ( !isNonNegativeInteger( length ) ) {
throw new TypeError( 'invalid argument. Last argument must be a nonnegative integer. Value: `' + length + '`.' );
}
if ( length > buf.byteLength ) {
throw new RangeError( 'invalid argument. Last argument must not exceed the number of bytes in the input ArrayBuffer. Value: `' + length + '`.' );
}
len = length;
} else {
len = buf.byteLength - offset;
}
} else {
offset = 0;
len = buf.byteLength;
}
// Address Node v5.x where providing an empty ArrayBuffer throws an error:
if ( len === 0 && version < 6 ) {
return Buffer.from( [] );
}
return Buffer.from( buf, offset, len );
}
// EXPORTS //
module.exports = fromArrayBuffer;