79 lines
2.1 KiB
JavaScript
79 lines
2.1 KiB
JavaScript
//
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// Utility functions.
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//
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// Copyright (c) 2016 Samuel Groß
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//
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// Return the hexadecimal representation of the given byte.
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function hex(b) {
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return ('0' + b.toString(16)).substr(-2);
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}
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// Return the hexadecimal representation of the given byte array.
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function hexlify(bytes) {
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var res = [];
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for (var i = 0; i < bytes.length; i++)
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res.push(hex(bytes[i]));
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return res.join('');
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}
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// Return the binary data represented by the given hexdecimal string.
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function unhexlify(hexstr) {
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if (hexstr.length % 2 == 1)
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throw new TypeError("Invalid hex string");
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var bytes = new Uint8Array(hexstr.length / 2);
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for (var i = 0; i < hexstr.length; i += 2)
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bytes[i/2] = parseInt(hexstr.substr(i, 2), 16);
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return bytes;
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}
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function hexdump(data) {
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if (typeof data.BYTES_PER_ELEMENT !== 'undefined')
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data = Array.from(data);
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var lines = [];
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for (var i = 0; i < data.length; i += 16) {
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var chunk = data.slice(i, i+16);
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var parts = chunk.map(hex);
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if (parts.length > 8)
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parts.splice(8, 0, ' ');
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lines.push(parts.join(' '));
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}
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return lines.join('\n');
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}
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// Simplified version of the similarly named python module.
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var Struct = (function() {
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// Allocate these once to avoid unecessary heap allocations during pack/unpack operations.
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var buffer = new ArrayBuffer(8);
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var byteView = new Uint8Array(buffer);
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var uint32View = new Uint32Array(buffer);
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var float64View = new Float64Array(buffer);
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return {
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pack: function(type, value) {
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var view = type; // See below
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view[0] = value;
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return new Uint8Array(buffer, 0, type.BYTES_PER_ELEMENT);
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},
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unpack: function(type, bytes) {
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if (bytes.length !== type.BYTES_PER_ELEMENT)
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throw Error("Invalid bytearray");
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var view = type; // See below
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byteView.set(bytes);
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return view[0];
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},
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// Available types.
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int8: byteView,
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int32: uint32View,
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float64: float64View
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};
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})();
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