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Added BCD operations with tests

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This commit is contained in:
n1474335 2017-07-19 15:29:37 +00:00
parent bcaef8ba54
commit c773edceb9
6 changed files with 382 additions and 1 deletions
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2
src/core/config/Categories.js
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@ -46,6 +46,8 @@ const Categories = [
"From Base58",
"To Base",
"From Base",
"To BCD",
"From BCD",
"To HTML Entity",
"From HTML Entity",
"URL Encode",

59
src/core/config/OperationConfig.js
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@ -2,6 +2,7 @@ import FlowControl from "../FlowControl.js";
import Base from "../operations/Base.js";
import Base58 from "../operations/Base58.js";
import Base64 from "../operations/Base64.js";
import BCD from "../operations/BCD.js";
import BitwiseOp from "../operations/BitwiseOp.js";
import ByteRepr from "../operations/ByteRepr.js";
import CharEnc from "../operations/CharEnc.js";
@ -3507,6 +3508,64 @@ const OperationConfig = {
}
]
},
"From BCD": {
description: "Binary-Coded Decimal (BCD) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. Special bit patterns are sometimes used for a sign.",
run: BCD.runFromBCD,
inputType: "string",
outputType: "number",
args: [
{
name: "Scheme",
type: "option",
value: BCD.ENCODING_SCHEME
},
{
name: "Packed",
type: "boolean",
value: true
},
{
name: "Signed",
type: "boolean",
value: false
},
{
name: "Input format",
type: "option",
value: BCD.FORMAT
}
]
},
"To BCD": {
description: "Binary-Coded Decimal (BCD) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. Special bit patterns are sometimes used for a sign",
run: BCD.runToBCD,
inputType: "number",
outputType: "string",
args: [
{
name: "Scheme",
type: "option",
value: BCD.ENCODING_SCHEME
},
{
name: "Packed",
type: "boolean",
value: true
},
{
name: "Signed",
type: "boolean",
value: false
},
{
name: "Output format",
type: "option",
value: BCD.FORMAT
}
]
},
};
export default OperationConfig;

214
src/core/operations/BCD.js Executable file
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@ -0,0 +1,214 @@
import Utils from "../Utils.js";
/**
* Binary-Coded Decimal operations.
*
* @author n1474335 [n1474335@gmail.com]
* @copyright Crown Copyright 2017
* @license Apache-2.0
*
* @namespace
*/
const BCD = {
/**
* @constant
* @default
*/
ENCODING_SCHEME: [
"8 4 2 1",
"7 4 2 1",
"4 2 2 1",
"2 4 2 1",
"8 4 -2 -1",
"Excess-3",
"IBM 8 4 2 1",
],
/**
* Lookup table for the binary value of each digit representation.
*
* I wrote a very nice algorithm to generate 8 4 2 1 encoding programatically,
* but unfortunately it's much easier (if less elegant) to use lookup tables
* when supporting multiple encoding schemes.
*
* "Practicality beats purity" - PEP 20
*
* In some schemes it is possible to represent the same value in multiple ways.
* For instance, in 4 2 2 1 encoding, 0100 and 0010 both represent 2. Support
* has not yet been added for this.
*
* @constant
*/
ENCODING_LOOKUP: {
"8 4 2 1": [0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
"7 4 2 1": [0, 1, 2, 3, 4, 5, 6, 8, 9, 10],
"4 2 2 1": [0, 1, 4, 5, 8, 9, 12, 13, 14, 15],
"2 4 2 1": [0, 1, 2, 3, 4, 11, 12, 13, 14, 15],
"8 4 -2 -1": [0, 7, 6, 5, 4, 11, 10, 9, 8, 15],
"Excess-3": [3, 4, 5, 6, 7, 8, 9, 10, 11, 12],
"IBM 8 4 2 1": [10, 1, 2, 3, 4, 5, 6, 7, 8, 9],
},
/**
* @default
* @constant
*/
FORMAT: ["Nibbles", "Bytes", "Raw"],
/**
* To BCD operation.
*
* @param {number} input
* @param {Object[]} args
* @returns {string}
*/
runToBCD: function(input, args) {
if (isNaN(input))
return "Invalid input";
if (Math.floor(input) !== input)
return "Fractional values are not supported by BCD";
const encoding = BCD.ENCODING_LOOKUP[args[0]],
packed = args[1],
signed = args[2],
outputFormat = args[3];
// Split input number up into separate digits
const digits = input.toString().split("");
if (digits[0] === "-" || digits[0] === "+") {
digits.shift();
}
let nibbles = [];
digits.forEach(d => {
const n = parseInt(d, 10);
nibbles.push(encoding[n]);
});
if (signed) {
if (packed && digits.length % 2 === 0) {
// If there are an even number of digits, we add a leading 0 so
// that the sign nibble doesn't sit in its own byte, leading to
// ambiguity around whether the number ends with a 0 or not.
nibbles.unshift(encoding[0]);
}
nibbles.push(input > 0 ? 12 : 13);
// 12 ("C") for + (credit)
// 13 ("D") for - (debit)
}
let bytes = [];
if (packed) {
let encoded = 0,
little = false;
nibbles.forEach(n => {
encoded ^= little ? n : (n << 4);
if (little) {
bytes.push(encoded);
encoded = 0;
}
little = !little;
});
if (little) bytes.push(encoded);
} else {
bytes = nibbles;
// Add null high nibbles
nibbles = nibbles.map(n => {
return [0, n];
}).reduce((a, b) => {
return a.concat(b);
});
}
// Output
switch (outputFormat) {
case "Nibbles":
return nibbles.map(n => {
return Utils.padLeft(n.toString(2), 4);
}).join(" ");
case "Bytes":
return bytes.map(b => {
return Utils.padLeft(b.toString(2), 8);
}).join(" ");
case "Raw":
default:
return Utils.byteArrayToChars(bytes);
}
},
/**
* From BCD operation.
*
* @param {string} input
* @param {Object[]} args
* @returns {number}
*/
runFromBCD: function(input, args) {
const encoding = BCD.ENCODING_LOOKUP[args[0]],
packed = args[1],
signed = args[2],
inputFormat = args[3];
let nibbles = [],
output = "",
byteArray;
// Normalise the input
switch (inputFormat) {
case "Nibbles":
case "Bytes":
input = input.replace(/\s/g, "");
for (let i = 0; i < input.length; i += 4) {
nibbles.push(parseInt(input.substr(i, 4), 2));
}
break;
case "Raw":
default:
byteArray = Utils.strToByteArray(input);
byteArray.forEach(b => {
nibbles.push(b >>> 4);
nibbles.push(b & 15);
});
break;
}
if (!packed) {
// Discard each high nibble
for (let i = 0; i < nibbles.length; i++) {
nibbles.splice(i, 1);
}
}
if (signed) {
const sign = nibbles.pop();
if (sign === 13 ||
sign === 11) {
// Negative
output += "-";
}
}
nibbles.forEach(n => {
if (isNaN(n)) throw "Invalid input";
let val = encoding.indexOf(n);
if (val < 0) throw `Value ${Utils.bin(n, 4)} not in encoding scheme`;
output += val.toString();
});
return parseInt(output, 10);
},
};
export default BCD;

4
src/web/html/index.html
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@ -35,7 +35,9 @@
"use strict";
// Load theme before the preloader is shown
document.querySelector(":root").className = JSON.parse(localStorage.getItem("options")).theme;
try {
document.querySelector(":root").className = JSON.parse(localStorage.getItem("options")).theme;
} catch (e) {}
// Define loading messages
const loadingMsgs = [

1
test/index.js
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@ -12,6 +12,7 @@ import "babel-polyfill";
import TestRegister from "./TestRegister.js";
import "./tests/operations/Base58.js";
import "./tests/operations/BCD.js";
import "./tests/operations/ByteRepr.js";
import "./tests/operations/CharEnc.js";
import "./tests/operations/Cipher.js";

103
test/tests/operations/BCD.js Normal file
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@ -0,0 +1,103 @@
/**
* BCD tests
*
* @author n1474335 [n1474335@gmail.com]
* @copyright Crown Copyright 2017
* @license Apache-2.0
*/
import TestRegister from "../../TestRegister.js";
TestRegister.addTests([
{
name: "To BCD: default 0",
input: "0",
expectedOutput: "0000",
recipeConfig: [
{
"op": "To BCD",
"args": ["8 4 2 1", true, false, "Nibbles"]
}
]
},
{
name: "To BCD: unpacked nibbles",
input: "1234567890",
expectedOutput: "0000 0001 0000 0010 0000 0011 0000 0100 0000 0101 0000 0110 0000 0111 0000 1000 0000 1001 0000 0000",
recipeConfig: [
{
"op": "To BCD",
"args": ["8 4 2 1", false, false, "Nibbles"]
}
]
},
{
name: "To BCD: packed, signed bytes",
input: "1234567890",
expectedOutput: "00000001 00100011 01000101 01100111 10001001 00001100",
recipeConfig: [
{
"op": "To BCD",
"args": ["8 4 2 1", true, true, "Bytes"]
}
]
},
{
name: "To BCD: packed, signed nibbles, 8 4 -2 -1",
input: "-1234567890",
expectedOutput: "0000 0111 0110 0101 0100 1011 1010 1001 1000 1111 0000 1101",
recipeConfig: [
{
"op": "To BCD",
"args": ["8 4 -2 -1", true, true, "Nibbles"]
}
]
},
{
name: "From BCD: default 0",
input: "0000",
expectedOutput: "0",
recipeConfig: [
{
"op": "From BCD",
"args": ["8 4 2 1", true, false, "Nibbles"]
}
]
},
{
name: "From BCD: packed, signed bytes",
input: "00000001 00100011 01000101 01100111 10001001 00001101",
expectedOutput: "-1234567890",
recipeConfig: [
{
"op": "From BCD",
"args": ["8 4 2 1", true, true, "Bytes"]
}
]
},
{
name: "From BCD: Excess-3, unpacked, unsigned",
input: "00000100 00000101 00000110 00000111 00001000 00001001 00001010 00001011 00001100 00000011",
expectedOutput: "1234567890",
recipeConfig: [
{
"op": "From BCD",
"args": ["Excess-3", false, false, "Nibbles"]
}
]
},
{
name: "BCD: raw 4 2 2 1, packed, signed",
input: "1234567890",
expectedOutput: "1234567890",
recipeConfig: [
{
"op": "To BCD",
"args": ["4 2 2 1", true, true, "Raw"]
},
{
"op": "From BCD",
"args": ["4 2 2 1", true, true, "Raw"]
}
]
},
]);