From 88ff414a24987a8ef2de2caa1c638b65dcae374f Mon Sep 17 00:00:00 2001 From: Project Nayuki Date: Sat, 23 Jun 2018 16:16:04 +0000 Subject: [PATCH] Added TypeScript port of the library. --- Readme.markdown | 22 +- typescript/qrcodegen-demo.ts | 180 +++++ typescript/qrcodegen-js-demo.html | 121 ++++ typescript/qrcodegen.ts | 1013 +++++++++++++++++++++++++++++ 4 files changed, 1334 insertions(+), 2 deletions(-) create mode 100644 typescript/qrcodegen-demo.ts create mode 100644 typescript/qrcodegen-js-demo.html create mode 100644 typescript/qrcodegen.ts diff --git a/Readme.markdown b/Readme.markdown index 0450524..a0200c9 100644 --- a/Readme.markdown +++ b/Readme.markdown @@ -15,10 +15,10 @@ Features Core features: -* Available in 6 programming languages, all with nearly equal functionality: Java, JavaScript, Python, C++, C, Rust +* Available in 7 programming languages, all with nearly equal functionality: Java, JavaScript, TypeScript, Python, C++, C, Rust * Significantly shorter code but more documentation comments compared to competing libraries * Supports encoding all 40 versions (sizes) and all 4 error correction levels, as per the QR Code Model 2 standard -* Output formats: Raw modules/pixels of the QR symbol (all languages), SVG XML string (all languages except C), `BufferedImage` raster bitmap (Java only), HTML5 canvas (JavaScript only) +* Output formats: Raw modules/pixels of the QR symbol (all languages), SVG XML string (all languages except C), `BufferedImage` raster bitmap (Java only), HTML5 canvas (JavaScript and TypeScript only) * Encodes numeric and special-alphanumeric text in less space than general text * Open source code under the permissive MIT License @@ -79,6 +79,24 @@ JavaScript language: } } +TypeScript language: + + // Simple operation + let qr0: qrcodegen.QrCode = qrcodegen.QrCode.encodeText( + "Hello, world!", qrcodegen.QrCode_Ecc.MEDIUM); + let svg: string = qr0.toSvgString(4); + + // Manual operation + let segs: Array = + qrcodegen.QrSegment.makeSegments("3141592653589793238462643383"); + let qr1: qrcodegen.QrCode = qrcodegen.QrCode.encodeSegments( + segs, qrcodegen.QrCode_Ecc.HIGH, 5, 5, 2, false); + for (let y = 0; y < qr1.size; y++) { + for (let x = 0; x < qr1.size; x++) { + (... paint qr1.getModule(x, y) ...) + } + } + Python language: from qrcodegen import * diff --git a/typescript/qrcodegen-demo.ts b/typescript/qrcodegen-demo.ts new file mode 100644 index 0000000..35cdf87 --- /dev/null +++ b/typescript/qrcodegen-demo.ts @@ -0,0 +1,180 @@ +/* + * QR Code generator demo (TypeScript) + * + * Copyright (c) Project Nayuki. (MIT License) + * https://www.nayuki.io/page/qr-code-generator-library + * + * Permission is hereby granted, free of charge, to any person obtaining a copy of + * this software and associated documentation files (the "Software"), to deal in + * the Software without restriction, including without limitation the rights to + * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of + * the Software, and to permit persons to whom the Software is furnished to do so, + * subject to the following conditions: + * - The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * - The Software is provided "as is", without warranty of any kind, express or + * implied, including but not limited to the warranties of merchantability, + * fitness for a particular purpose and noninfringement. In no event shall the + * authors or copyright holders be liable for any claim, damages or other + * liability, whether in an action of contract, tort or otherwise, arising from, + * out of or in connection with the Software or the use or other dealings in the + * Software. + */ + +"use strict"; + + +{ + const myWindow = window as any; + + + /*---- Functions called from HTML code ----*/ + + myWindow.redrawQrCode = (): void => { + // Show/hide rows based on bitmap/vector image output + const bitmapOutput: boolean = getInput("output-format-bitmap").checked; + const scaleRow : HTMLElement = getElem("scale-row"); + const svgXmlRow: HTMLElement = getElem("svg-xml-row"); + if (bitmapOutput) { + scaleRow.style.removeProperty("display"); + svgXmlRow.style.display = "none"; + } else { + scaleRow.style.display = "none"; + svgXmlRow.style.removeProperty("display"); + } + const svgXml = getElem("svg-xml-output") as HTMLTextAreaElement; + svgXml.value = ""; + + // Reset output images in case of early termination + const canvas = getElem("qrcode-canvas") as HTMLCanvasElement; + const svg = (document.getElementById("qrcode-svg") as Element) as SVGElement; + canvas.style.display = "none"; + svg.style.display = "none"; + + // Returns a QrCode.Ecc object based on the radio buttons in the HTML form. + function getInputErrorCorrectionLevel(): qrcodegen.QrCode_Ecc { + if (getInput("errcorlvl-medium").checked) + return qrcodegen.QrCode_Ecc.MEDIUM; + else if (getInput("errcorlvl-quartile").checked) + return qrcodegen.QrCode_Ecc.QUARTILE; + else if (getInput("errcorlvl-high").checked) + return qrcodegen.QrCode_Ecc.HIGH; + else // In case no radio button is depressed + return qrcodegen.QrCode_Ecc.LOW; + } + + // Get form inputs and compute QR Code + const ecl: qrcodegen.QrCode_Ecc = getInputErrorCorrectionLevel(); + const text: string = (getElem("text-input") as HTMLTextAreaElement).value; + const segs: Array = qrcodegen.QrSegment.makeSegments(text); + const minVer: number = parseInt(getInput("version-min-input").value, 10); + const maxVer: number = parseInt(getInput("version-max-input").value, 10); + const mask: number = parseInt(getInput("mask-input").value, 10); + const boostEcc: boolean = getInput("boost-ecc-input").checked; + const qr: qrcodegen.QrCode = qrcodegen.QrCode.encodeSegments(segs, ecl, minVer, maxVer, mask, boostEcc); + + // Draw image output + const border: number = parseInt(getInput("border-input").value, 10); + if (border < 0 || border > 100) + return; + if (bitmapOutput) { + const scale: number = parseInt(getInput("scale-input").value, 10); + if (scale <= 0 || scale > 30) + return; + qr.drawCanvas(scale, border, canvas); + canvas.style.removeProperty("display"); + } else { + const code: string = qr.toSvgString(border); + const viewBox: string = (/ viewBox="([^"]*)"/.exec(code) as RegExpExecArray)[1]; + const pathD: string = (/ d="([^"]*)"/.exec(code) as RegExpExecArray)[1]; + svg.setAttribute("viewBox", viewBox); + (svg.querySelector("path") as Element).setAttribute("d", pathD); + svg.style.removeProperty("display"); + svgXml.value = qr.toSvgString(border); + } + + // Returns a string to describe the given list of segments. + function describeSegments(segs: Array): string { + if (segs.length == 0) + return "none"; + else if (segs.length == 1) { + const mode: qrcodegen.QrSegment_Mode = segs[0].mode; + const Mode = qrcodegen.QrSegment_Mode; + if (mode == Mode.NUMERIC ) return "numeric"; + if (mode == Mode.ALPHANUMERIC) return "alphanumeric"; + if (mode == Mode.BYTE ) return "byte"; + if (mode == Mode.KANJI ) return "kanji"; + return "unknown"; + } else + return "multiple"; + } + + // Returns the number of Unicode code points in the given UTF-16 string. + function countUnicodeChars(str: string): number { + let result: number = 0; + for (let i = 0; i < str.length; i++, result++) { + const c: number = str.charCodeAt(i); + if (c < 0xD800 || c >= 0xE000) + continue; + else if (0xD800 <= c && c < 0xDC00 && i + 1 < str.length) { // High surrogate + i++; + const d: number = str.charCodeAt(i); + if (0xDC00 <= d && d < 0xE000) // Low surrogate + continue; + } + throw "Invalid UTF-16 string"; + } + return result; + } + + // Show the QR Code symbol's statistics as a string + getElem("statistics-output").textContent = `QR Code version = ${qr.version}, ` + + `mask pattern = ${qr.mask}, ` + + `character count = ${countUnicodeChars(text)},\n` + + `encoding mode = ${describeSegments(segs)}, ` + + `error correction = level ${"LMQH".charAt(qr.errorCorrectionLevel.ordinal)}, ` + + `data bits = ${qrcodegen.QrSegment.getTotalBits(segs, qr.version) as number}.`; + } + + + myWindow.handleVersionMinMax = (which: "min"|"max"): void => { + const minElem: HTMLInputElement = getInput("version-min-input"); + const maxElem: HTMLInputElement = getInput("version-max-input"); + let minVal: number = parseInt(minElem.value, 10); + let maxVal: number = parseInt(maxElem.value, 10); + minVal = Math.max(Math.min(minVal, qrcodegen.QrCode.MAX_VERSION), qrcodegen.QrCode.MIN_VERSION); + maxVal = Math.max(Math.min(maxVal, qrcodegen.QrCode.MAX_VERSION), qrcodegen.QrCode.MIN_VERSION); + if (which == "min" && minVal > maxVal) + maxVal = minVal; + else if (which == "max" && maxVal < minVal) + minVal = maxVal; + minElem.value = minVal.toString(); + maxElem.value = maxVal.toString(); + myWindow.redrawQrCode(); + } + + + + /*---- Private helper functions ----*/ + + function getElem(id: string): HTMLElement { + const result: HTMLElement|null = document.getElementById(id); + if (result instanceof HTMLElement) + return result; + throw "Assertion error"; + } + + + function getInput(id: string): HTMLInputElement { + const result: HTMLElement = getElem(id); + if (result instanceof HTMLInputElement) + return result; + throw "Assertion error"; + } + + + + /*---- Initialization ----*/ + + myWindow.redrawQrCode(); +} diff --git a/typescript/qrcodegen-js-demo.html b/typescript/qrcodegen-js-demo.html new file mode 100644 index 0000000..e18b094 --- /dev/null +++ b/typescript/qrcodegen-js-demo.html @@ -0,0 +1,121 @@ + + + + + + QR Code generator library demo (TypeScript) + + + + +

QR Code generator demo library (TypeScript)

+
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Text string:
QR Code: + + + + + +
Error correction: + + + + +
Output format: + + +
Border: modules
Scale: pixels per module
Version range:Minimum = , maximum =
Mask pattern: (−1 for automatic, 0 to 7 for manual)
Boost ECC:
Statistics:
SVG XML code: + +
+
+ + + +
+

Copyright © Project Nayuki – https://www.nayuki.io/page/qr-code-generator-library

+ + diff --git a/typescript/qrcodegen.ts b/typescript/qrcodegen.ts new file mode 100644 index 0000000..8702e73 --- /dev/null +++ b/typescript/qrcodegen.ts @@ -0,0 +1,1013 @@ +/* + * QR Code generator library (TypeScript) + * + * Copyright (c) Project Nayuki. (MIT License) + * https://www.nayuki.io/page/qr-code-generator-library + * + * Permission is hereby granted, free of charge, to any person obtaining a copy of + * this software and associated documentation files (the "Software"), to deal in + * the Software without restriction, including without limitation the rights to + * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of + * the Software, and to permit persons to whom the Software is furnished to do so, + * subject to the following conditions: + * - The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * - The Software is provided "as is", without warranty of any kind, express or + * implied, including but not limited to the warranties of merchantability, + * fitness for a particular purpose and noninfringement. In no event shall the + * authors or copyright holders be liable for any claim, damages or other + * liability, whether in an action of contract, tort or otherwise, arising from, + * out of or in connection with the Software or the use or other dealings in the + * Software. + */ + +"use strict"; + + +namespace qrcodegen { + + type bit = number; + type byte = number; + type int = number; + + + /*---- QR Code symbol class ----*/ + + /* + * A class that represents an immutable square grid of black and white cells for a QR Code symbol, + * with associated static functions to create a QR Code from user-supplied textual or binary data. + * This class covers the QR Code model 2 specification, supporting all versions (sizes) + * from 1 to 40, all 4 error correction levels. + * This constructor creates a new QR Code symbol with the given version number, error correction level, binary data array, + * and mask number. mask = -1 is for automatic choice, or 0 to 7 for fixed choice. This is a cumbersome low-level constructor + * that should not be invoked directly by the user. To go one level up, see the QrCode.encodeSegments() function. + */ + export class QrCode { + + /*-- Public static factory functions --*/ + + // Returns a QR Code symbol representing the specified Unicode text string at the specified error correction level. + // As a conservative upper bound, this function is guaranteed to succeed for strings that have 738 or fewer + // Unicode code points (not UTF-16 code units) if the low error correction level is used. The smallest possible + // QR Code version is automatically chosen for the output. The ECC level of the result may be higher than the + // ecl argument if it can be done without increasing the version. + public static encodeText(text: string, ecl: QrCode_Ecc): QrCode { + let segs: Array = qrcodegen.QrSegment.makeSegments(text); + return QrCode.encodeSegments(segs, ecl); + } + + + // Returns a QR Code symbol representing the given binary data string at the given error correction level. + // This function always encodes using the binary segment mode, not any text mode. The maximum number of + // bytes allowed is 2953. The smallest possible QR Code version is automatically chosen for the output. + // The ECC level of the result may be higher than the ecl argument if it can be done without increasing the version. + public static encodeBinary(data: Array, ecl: QrCode_Ecc): QrCode { + let seg: QrSegment = qrcodegen.QrSegment.makeBytes(data); + return QrCode.encodeSegments([seg], ecl); + } + + + // Returns a QR Code symbol representing the given data segments with the given encoding parameters. + // The smallest possible QR Code version within the given range is automatically chosen for the output. + // This function allows the user to create a custom sequence of segments that switches + // between modes (such as alphanumeric and binary) to encode text more efficiently. + // This function is considered to be lower level than simply encoding text or binary data. + public static encodeSegments(segs: Array, ecl: QrCode_Ecc, + minVersion: int = 1, maxVersion: int = 1, + mask: int = -1, boostEcl: boolean = true): QrCode { + + if (!(QrCode.MIN_VERSION <= minVersion && minVersion <= maxVersion && maxVersion <= QrCode.MAX_VERSION) + || mask < -1 || mask > 7) + throw "Invalid value"; + + // Find the minimal version number to use + let version: int; + let dataUsedBits: int; + for (version = minVersion; ; version++) { + let dataCapacityBits: int = QrCode.getNumDataCodewords(version, ecl) * 8; // Number of data bits available + let usedBits: number|null = QrSegment.getTotalBits(segs, version); + if (usedBits != null && usedBits <= dataCapacityBits) { + dataUsedBits = usedBits; + break; // This version number is found to be suitable + } + if (version >= maxVersion) // All versions in the range could not fit the given data + throw "Data too long"; + } + + // Increase the error correction level while the data still fits in the current version number + [QrCode_Ecc.MEDIUM, QrCode_Ecc.QUARTILE, QrCode_Ecc.HIGH].forEach((newEcl: QrCode_Ecc) => { + if (boostEcl && dataUsedBits <= QrCode.getNumDataCodewords(version, newEcl) * 8) + ecl = newEcl; + }); + + // Create the data bit string by concatenating all segments + let dataCapacityBits: int = QrCode.getNumDataCodewords(version, ecl) * 8; + let bb = new BitBuffer(); + segs.forEach((seg: QrSegment) => { + bb.appendBits(seg.mode.modeBits, 4); + bb.appendBits(seg.numChars, seg.mode.numCharCountBits(version)); + seg.getBits().forEach( + (b: bit) => bb.push(b)); + }); + + // Add terminator and pad up to a byte if applicable + bb.appendBits(0, Math.min(4, dataCapacityBits - bb.length)); + bb.appendBits(0, (8 - bb.length % 8) % 8); + + // Pad with alternate bytes until data capacity is reached + for (let padByte = 0xEC; bb.length < dataCapacityBits; padByte ^= 0xEC ^ 0x11) + bb.appendBits(padByte, 8); + if (bb.length % 8 != 0) + throw "Assertion error"; + + // Create the QR Code symbol + return new QrCode(bb.getBytes(), mask, version, ecl); + } + + + /*-- Fields --*/ + + // This QR Code symbol's version number, which is always between 1 and 40 (inclusive). + public readonly version: int; + + // The width and height of this QR Code symbol, measured in modules. + // Always equal to version * 4 + 17, in the range 21 to 177. + public readonly size: int; + + // The error correction level used in this QR Code symbol. + public readonly errorCorrectionLevel: QrCode_Ecc; + + // The mask pattern used in this QR Code symbol, in the range 0 to 7 (i.e. unsigned 3-bit integer). + // Note that even if the constructor was called with automatic masking requested + // (mask = -1), the resulting object will still have a mask value between 0 and 7. + public readonly mask: int; + + // The modules of this QR Code symbol (false = white, true = black). + private readonly modules: Array> = []; + + // Indicates function modules that are not subjected to masking. + private readonly isFunction: Array> = []; + + + public constructor(datacodewords: Array, mask: int, version: int, errCorLvl: QrCode_Ecc) { + // Check arguments and handle simple scalar fields + if (mask < -1 || mask > 7) + throw "Mask value out of range"; + if (version < QrCode.MIN_VERSION || version > QrCode.MAX_VERSION) + throw "Version value out of range"; + this.version = version; + this.size = version * 4 + 17; + this.errorCorrectionLevel = errCorLvl; + + // Initialize both grids to be size*size arrays of Boolean false + let row: Array = []; + for (let i = 0; i < this.size; i++) + row.push(false); + for (let i = 0; i < this.size; i++) { + this.modules.push(row.slice()); + this.isFunction.push(row.slice()); + } + + // Handle grid fields, draw function patterns, draw all codewords + this.drawFunctionPatterns(); + let allCodewords: Array = this.appendErrorCorrection(datacodewords); + this.drawCodewords(allCodewords); + + // Handle masking + if (mask == -1) { // Automatically choose best mask + let minPenalty: int = 1000000000; + for (let i = 0; i < 8; i++) { + this.drawFormatBits(i); + this.applyMask(i); + let penalty: int = this.getPenaltyScore(); + if (penalty < minPenalty) { + mask = i; + minPenalty = penalty; + } + this.applyMask(i); // Undoes the mask due to XOR + } + } + if (mask < 0 || mask > 7) + throw "Assertion error"; + this.mask = mask; + this.drawFormatBits(mask); // Overwrite old format bits + this.applyMask(mask); // Apply the final choice of mask + } + + + /*-- Accessor methods --*/ + + // Returns the color of the module (pixel) at the given coordinates, which is either + // false for white or true for black. The top left corner has the coordinates (x=0, y=0). + // If the given coordinates are out of bounds, then false (white) is returned. + public getModule(x: int, y: int): boolean { + return 0 <= x && x < this.size && 0 <= y && y < this.size && this.modules[y][x]; + } + + + /*-- Public instance methods --*/ + + // Draws this QR Code symbol with the given module scale and number of modules onto the given HTML canvas element. + // The canvas will be resized to a width and height of (this.size + border * 2) * scale. The painted image will be purely + // black and white with no transparent regions. The scale must be a positive integer, and the border must be a non-negative integer. + public drawCanvas(scale: int, border: int, canvas: HTMLCanvasElement): void { + if (scale <= 0 || border < 0) + throw "Value out of range"; + let width: int = (this.size + border * 2) * scale; + canvas.width = width; + canvas.height = width; + let ctx = canvas.getContext("2d") as CanvasRenderingContext2D; + for (let y = -border; y < this.size + border; y++) { + for (let x = -border; x < this.size + border; x++) { + ctx.fillStyle = this.getModule(x, y) ? "#000000" : "#FFFFFF"; + ctx.fillRect((x + border) * scale, (y + border) * scale, scale, scale); + } + } + } + + + // Based on the given number of border modules to add as padding, this returns a + // string whose contents represents an SVG XML file that depicts this QR Code symbol. + // Note that Unix newlines (\n) are always used, regardless of the platform. + public toSvgString(border: int): string { + if (border < 0) + throw "Border must be non-negative"; + let parts: Array = []; + for (let y = -border; y < this.size + border; y++) { + for (let x = -border; x < this.size + border; x++) { + if (this.getModule(x, y)) + parts.push(`M${x + border},${y + border}h1v1h-1z`); + } + } + return ` + + + + + +` + } + + + /*-- Private helper methods for constructor: Drawing function modules --*/ + + private drawFunctionPatterns(): void { + // Draw horizontal and vertical timing patterns + for (let i = 0; i < this.size; i++) { + this.setFunctionModule(6, i, i % 2 == 0); + this.setFunctionModule(i, 6, i % 2 == 0); + } + + // Draw 3 finder patterns (all corners except bottom right; overwrites some timing modules) + this.drawFinderPattern(3, 3); + this.drawFinderPattern(this.size - 4, 3); + this.drawFinderPattern(3, this.size - 4); + + // Draw numerous alignment patterns + let alignPatPos: Array = QrCode.getAlignmentPatternPositions(this.version); + let numAlign: int = alignPatPos.length; + for (let i = 0; i < numAlign; i++) { + for (let j = 0; j < numAlign; j++) { + if (i == 0 && j == 0 || i == 0 && j == numAlign - 1 || i == numAlign - 1 && j == 0) + continue; // Skip the three finder corners + else + this.drawAlignmentPattern(alignPatPos[i], alignPatPos[j]); + } + } + + // Draw configuration data + this.drawFormatBits(0); // Dummy mask value; overwritten later in the constructor + this.drawVersion(); + } + + + // Draws two copies of the format bits (with its own error correction code) + // based on the given mask and this object's error correction level field. + private drawFormatBits(mask: int): void { + // Calculate error correction code and pack bits + let data: int = this.errorCorrectionLevel.formatBits << 3 | mask; // errCorrLvl is uint2, mask is uint3 + let rem: int = data; + for (let i = 0; i < 10; i++) + rem = (rem << 1) ^ ((rem >>> 9) * 0x537); + data = data << 10 | rem; + data ^= 0x5412; // uint15 + if (data >>> 15 != 0) + throw "Assertion error"; + + // Draw first copy + for (let i = 0; i <= 5; i++) + this.setFunctionModule(8, i, getBit(data, i)); + this.setFunctionModule(8, 7, getBit(data, 6)); + this.setFunctionModule(8, 8, getBit(data, 7)); + this.setFunctionModule(7, 8, getBit(data, 8)); + for (let i = 9; i < 15; i++) + this.setFunctionModule(14 - i, 8, getBit(data, i)); + + // Draw second copy + for (let i = 0; i <= 7; i++) + this.setFunctionModule(this.size - 1 - i, 8, getBit(data, i)); + for (let i = 8; i < 15; i++) + this.setFunctionModule(8, this.size - 15 + i, getBit(data, i)); + this.setFunctionModule(8, this.size - 8, true); + } + + + // Draws two copies of the version bits (with its own error correction code), + // based on this object's version field (which only has an effect for 7 <= version <= 40). + private drawVersion(): void { + if (this.version < 7) + return; + + // Calculate error correction code and pack bits + let rem: int = this.version; // version is uint6, in the range [7, 40] + for (let i = 0; i < 12; i++) + rem = (rem << 1) ^ ((rem >>> 11) * 0x1F25); + let data: int = this.version << 12 | rem; // uint18 + if (data >>> 18 != 0) + throw "Assertion error"; + + // Draw two copies + for (let i = 0; i < 18; i++) { + let bt: boolean = getBit(data, i); + let a: int = this.size - 11 + i % 3; + let b: int = Math.floor(i / 3); + this.setFunctionModule(a, b, bt); + this.setFunctionModule(b, a, bt); + } + } + + + // Draws a 9*9 finder pattern including the border separator, with the center module at (x, y). + private drawFinderPattern(x: int, y: int): void { + for (let i = -4; i <= 4; i++) { + for (let j = -4; j <= 4; j++) { + let dist: int = Math.max(Math.abs(i), Math.abs(j)); // Chebyshev/infinity norm + let xx: int = x + j; + let yy: int = y + i; + if (0 <= xx && xx < this.size && 0 <= yy && yy < this.size) + this.setFunctionModule(xx, yy, dist != 2 && dist != 4); + } + } + } + + + // Draws a 5*5 alignment pattern, with the center module at (x, y). + private drawAlignmentPattern(x: int, y: int): void { + for (let i = -2; i <= 2; i++) { + for (let j = -2; j <= 2; j++) + this.setFunctionModule(x + j, y + i, Math.max(Math.abs(i), Math.abs(j)) != 1); + } + } + + + // Sets the color of a module and marks it as a function module. + // Only used by the constructor. Coordinates must be in range. + private setFunctionModule(x: int, y: int, isBlack: boolean): void { + this.modules[y][x] = isBlack; + this.isFunction[y][x] = true; + } + + + /*-- Private helper methods for constructor: Codewords and masking --*/ + + // Returns a new byte string representing the given data with the appropriate error correction + // codewords appended to it, based on this object's version and error correction level. + private appendErrorCorrection(data: Array): Array { + const ver: int = this.version; + const ecl: QrCode_Ecc = this.errorCorrectionLevel; + if (data.length != QrCode.getNumDataCodewords(ver, ecl)) + throw "Invalid argument"; + + // Calculate parameter numbers + let numBlocks: int = QrCode_NUM_ERROR_CORRECTION_BLOCKS[ecl.ordinal][ver]; + let blockEccLen: int = QrCode_ECC_CODEWORDS_PER_BLOCK[ecl.ordinal][ver]; + let rawCodewords: int = Math.floor(QrCode.getNumRawDataModules(ver) / 8); + let numShortBlocks: int = numBlocks - rawCodewords % numBlocks; + let shortBlockLen: int = Math.floor(rawCodewords / numBlocks); + + // Split data into blocks and append ECC to each block + let blocks: Array> = []; + let rs = new ReedSolomonGenerator(blockEccLen); + for (let i = 0, k = 0; i < numBlocks; i++) { + let dat: Array = data.slice(k, k + shortBlockLen - blockEccLen + (i < numShortBlocks ? 0 : 1)); + k += dat.length; + let ecc: Array = rs.getRemainder(dat); + if (i < numShortBlocks) + dat.push(0); + ecc.forEach( + (b: byte) => dat.push(b)); + blocks.push(dat); + } + + // Interleave (not concatenate) the bytes from every block into a single sequence + let result: Array = []; + for (let i = 0; i < blocks[0].length; i++) { + for (let j = 0; j < blocks.length; j++) { + // Skip the padding byte in short blocks + if (i != shortBlockLen - blockEccLen || j >= numShortBlocks) + result.push(blocks[j][i]); + } + } + if (result.length != rawCodewords) + throw "Assertion error"; + return result; + } + + + // Draws the given sequence of 8-bit codewords (data and error correction) onto the entire + // data area of this QR Code symbol. Function modules need to be marked off before this is called. + private drawCodewords(data: Array): void { + if (data.length != Math.floor(QrCode.getNumRawDataModules(this.version) / 8)) + throw "Invalid argument"; + let i: int = 0; // Bit index into the data + // Do the funny zigzag scan + for (let right = this.size - 1; right >= 1; right -= 2) { // Index of right column in each column pair + if (right == 6) + right = 5; + for (let vert = 0; vert < this.size; vert++) { // Vertical counter + for (let j = 0; j < 2; j++) { + let x: int = right - j; // Actual x coordinate + let upward: boolean = ((right + 1) & 2) == 0; + let y: int = upward ? this.size - 1 - vert : vert; // Actual y coordinate + if (!this.isFunction[y][x] && i < data.length * 8) { + this.modules[y][x] = getBit(data[i >>> 3], 7 - (i & 7)); + i++; + } + // If there are any remainder bits (0 to 7), they are already + // set to 0/false/white when the grid of modules was initialized + } + } + } + if (i != data.length * 8) + throw "Assertion error"; + } + + + // XORs the data modules in this QR Code with the given mask pattern. Due to XOR's mathematical + // properties, calling applyMask(m) twice with the same value is equivalent to no change at all. + // This means it is possible to apply a mask, undo it, and try another mask. Note that a final + // well-formed QR Code symbol needs exactly one mask applied (not zero, not two, etc.). + private applyMask(mask: int): void { + if (mask < 0 || mask > 7) + throw "Mask value out of range"; + for (let y = 0; y < this.size; y++) { + for (let x = 0; x < this.size; x++) { + let invert: boolean; + switch (mask) { + case 0: invert = (x + y) % 2 == 0; break; + case 1: invert = y % 2 == 0; break; + case 2: invert = x % 3 == 0; break; + case 3: invert = (x + y) % 3 == 0; break; + case 4: invert = (Math.floor(x / 3) + Math.floor(y / 2)) % 2 == 0; break; + case 5: invert = x * y % 2 + x * y % 3 == 0; break; + case 6: invert = (x * y % 2 + x * y % 3) % 2 == 0; break; + case 7: invert = ((x + y) % 2 + x * y % 3) % 2 == 0; break; + default: throw "Assertion error"; + } + if (invert && !this.isFunction[y][x]) + this.modules[y][x] = !this.modules[y][x]; + } + } + } + + + // Calculates and returns the penalty score based on state of this QR Code's current modules. + // This is used by the automatic mask choice algorithm to find the mask pattern that yields the lowest score. + private getPenaltyScore(): int { + let result: int = 0; + + // Adjacent modules in row having same color + for (let y = 0; y < this.size; y++) { + for (let x = 0, runX = 0, colorX = false; x < this.size; x++) { + if (x == 0 || this.modules[y][x] != colorX) { + colorX = this.modules[y][x]; + runX = 1; + } else { + runX++; + if (runX == 5) + result += QrCode.PENALTY_N1; + else if (runX > 5) + result++; + } + } + } + // Adjacent modules in column having same color + for (let x = 0; x < this.size; x++) { + for (let y = 0, runY = 0, colorY = false; y < this.size; y++) { + if (y == 0 || this.modules[y][x] != colorY) { + colorY = this.modules[y][x]; + runY = 1; + } else { + runY++; + if (runY == 5) + result += QrCode.PENALTY_N1; + else if (runY > 5) + result++; + } + } + } + + // 2*2 blocks of modules having same color + for (let y = 0; y < this.size - 1; y++) { + for (let x = 0; x < this.size - 1; x++) { + let color: boolean = this.modules[y][x]; + if ( color == this.modules[y][x + 1] && + color == this.modules[y + 1][x] && + color == this.modules[y + 1][x + 1]) + result += QrCode.PENALTY_N2; + } + } + + // Finder-like pattern in rows + for (let y = 0; y < this.size; y++) { + for (let x = 0, bits = 0; x < this.size; x++) { + bits = ((bits << 1) & 0x7FF) | (this.modules[y][x] ? 1 : 0); + if (x >= 10 && (bits == 0x05D || bits == 0x5D0)) // Needs 11 bits accumulated + result += QrCode.PENALTY_N3; + } + } + // Finder-like pattern in columns + for (let x = 0; x < this.size; x++) { + for (let y = 0, bits = 0; y < this.size; y++) { + bits = ((bits << 1) & 0x7FF) | (this.modules[y][x] ? 1 : 0); + if (y >= 10 && (bits == 0x05D || bits == 0x5D0)) // Needs 11 bits accumulated + result += QrCode.PENALTY_N3; + } + } + + // Balance of black and white modules + let black: int = 0; + this.modules.forEach((row: Array) => { + row.forEach((color: boolean) => { + if (color) + black++; + }); + }); + let total: int = this.size * this.size; + // Find smallest k such that (45-5k)% <= dark/total <= (55+5k)% + for (let k = 0; black*20 < (9-k)*total || black*20 > (11+k)*total; k++) + result += QrCode.PENALTY_N4; + return result; + } + + + /*-- Private static helper functions QrCode --*/ + + // Returns a sequence of positions of the alignment patterns in ascending order. These positions are + // used on both the x and y axes. Each value in the resulting sequence is in the range [0, 177). + // This stateless pure function could be implemented as table of 40 variable-length lists of integers. + private static getAlignmentPatternPositions(ver: int): Array { + if (ver < QrCode.MIN_VERSION || ver > QrCode.MAX_VERSION) + throw "Version number out of range"; + else if (ver == 1) + return []; + else { + let size: int = ver * 4 + 17; + let numAlign: int = Math.floor(ver / 7) + 2; + let step: int; + if (ver != 32) + step = Math.ceil((size - 13) / (2 * numAlign - 2)) * 2; + else // C-C-C-Combo breaker! + step = 26; + + let result: Array = [6]; + for (let i = 0, pos = size - 7; i < numAlign - 1; i++, pos -= step) + result.splice(1, 0, pos); + return result; + } + } + + + // Returns the number of data bits that can be stored in a QR Code of the given version number, after + // all function modules are excluded. This includes remainder bits, so it might not be a multiple of 8. + // The result is in the range [208, 29648]. This could be implemented as a 40-entry lookup table. + private static getNumRawDataModules(ver: int): int { + if (ver < QrCode.MIN_VERSION || ver > QrCode.MAX_VERSION) + throw "Version number out of range"; + let result: int = (16 * ver + 128) * ver + 64; + if (ver >= 2) { + let numAlign: int = Math.floor(ver / 7) + 2; + result -= (25 * numAlign - 10) * numAlign - 55; + if (ver >= 7) + result -= 18 * 2; // Subtract version information + } + return result; + } + + + // Returns the number of 8-bit data (i.e. not error correction) codewords contained in any + // QR Code of the given version number and error correction level, with remainder bits discarded. + // This stateless pure function could be implemented as a (40*4)-cell lookup table. + private static getNumDataCodewords(ver: int, ecl: QrCode_Ecc): int { + if (ver < QrCode.MIN_VERSION || ver > QrCode.MAX_VERSION) + throw "Version number out of range"; + return Math.floor(QrCode.getNumRawDataModules(ver) / 8) - + QrCode_ECC_CODEWORDS_PER_BLOCK[ecl.ordinal][ver] * + QrCode_NUM_ERROR_CORRECTION_BLOCKS[ecl.ordinal][ver]; + } + + + /*-- Constants --*/ + + public static get MIN_VERSION(): int { return 1; } + public static get MAX_VERSION(): int { return 40; } + + + // For use in getPenaltyScore(), when evaluating which mask is best. + private static get PENALTY_N1(): int { return 3; } + private static get PENALTY_N2(): int { return 3; } + private static get PENALTY_N3(): int { return 40; } + private static get PENALTY_N4(): int { return 10; } + + } + + /*-- Private tables of constants --*/ + + const QrCode_ECC_CODEWORDS_PER_BLOCK: Array> = [ + // Version: (note that index 0 is for padding, and is set to an illegal value) + // 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 Error correction level + [ -1, 7, 10, 15, 20, 26, 18, 20, 24, 30, 18, 20, 24, 26, 30, 22, 24, 28, 30, 28, 28, 28, 28, 30, 30, 26, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30], // Low + [ -1, 10, 16, 26, 18, 24, 16, 18, 22, 22, 26, 30, 22, 22, 24, 24, 28, 28, 26, 26, 26, 26, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28], // Medium + [ -1, 13, 22, 18, 26, 18, 24, 18, 22, 20, 24, 28, 26, 24, 20, 30, 24, 28, 28, 26, 30, 28, 30, 30, 30, 30, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30], // Quartile + [ -1, 17, 28, 22, 16, 22, 28, 26, 26, 24, 28, 24, 28, 22, 24, 24, 30, 28, 28, 26, 28, 30, 24, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30], // High + ]; + + const QrCode_NUM_ERROR_CORRECTION_BLOCKS: Array> = [ + // Version: (note that index 0 is for padding, and is set to an illegal value) + // 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 Error correction level + [ -1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 4, 4, 4, 4, 4, 6, 6, 6, 6, 7, 8, 8, 9, 9, 10, 12, 12, 12, 13, 14, 15, 16, 17, 18, 19, 19, 20, 21, 22, 24, 25], // Low + [ -1, 1, 1, 1, 2, 2, 4, 4, 4, 5, 5, 5, 8, 9, 9, 10, 10, 11, 13, 14, 16, 17, 17, 18, 20, 21, 23, 25, 26, 28, 29, 31, 33, 35, 37, 38, 40, 43, 45, 47, 49], // Medium + [ -1, 1, 1, 2, 2, 4, 4, 6, 6, 8, 8, 8, 10, 12, 16, 12, 17, 16, 18, 21, 20, 23, 23, 25, 27, 29, 34, 34, 35, 38, 40, 43, 45, 48, 51, 53, 56, 59, 62, 65, 68], // Quartile + [ -1, 1, 1, 2, 4, 4, 4, 5, 6, 8, 8, 11, 11, 16, 16, 18, 16, 19, 21, 25, 25, 25, 34, 30, 32, 35, 37, 40, 42, 45, 48, 51, 54, 57, 60, 63, 66, 70, 74, 77, 81], // High + ]; + + + // Returns true iff the i'th bit of x is set to 1. + function getBit(x: int, i: int): boolean { + return ((x >>> i) & 1) != 0; + } + + + + /*---- Public helper enumeration ----*/ + + /* + * Represents the error correction level used in a QR Code symbol. + */ + export class QrCode_Ecc { + + /*-- Constants --*/ + + public static get LOW () { return new QrCode_Ecc(0, 1); } + public static get MEDIUM () { return new QrCode_Ecc(1, 0); } + public static get QUARTILE() { return new QrCode_Ecc(2, 3); } + public static get HIGH () { return new QrCode_Ecc(3, 2); } + + + /*-- Fields --*/ + + // In the range 0 to 3 (unsigned 2-bit integer). + public readonly ordinal: int; + + // (Package-private) In the range 0 to 3 (unsigned 2-bit integer). + public readonly formatBits: int; + + + /*-- Constructor --*/ + + private constructor(ord: int, fb: int) { + this.ordinal = ord; + this.formatBits = fb; + } + + } + + + + /*---- Data segment class ----*/ + + /* + * A public class that represents a character string to be encoded in a QR Code symbol. + * Each segment has a mode, and a sequence of characters that is already encoded as + * a sequence of bits. Instances of this class are immutable. + * This segment class imposes no length restrictions, but QR Codes have restrictions. + * Even in the most favorable conditions, a QR Code can only hold 7089 characters of data. + * Any segment longer than this is meaningless for the purpose of generating QR Codes. + */ + export class QrSegment { + + /*-- Static factory functions --*/ + + // Returns a segment representing the given binary data encoded in byte mode. + public static makeBytes(data: Array): QrSegment { + let bb = new BitBuffer(); + data.forEach( + (b: byte) => bb.appendBits(b, 8)); + return new QrSegment(QrSegment_Mode.BYTE, data.length, bb); + } + + + // Returns a segment representing the given string of decimal digits encoded in numeric mode. + public static makeNumeric(digits: string): QrSegment { + if (!this.NUMERIC_REGEX.test(digits)) + throw "String contains non-numeric characters"; + let bb = new BitBuffer(); + let i: int; + for (i = 0; i + 3 <= digits.length; i += 3) // Process groups of 3 + bb.appendBits(parseInt(digits.substr(i, 3), 10), 10); + let rem: int = digits.length - i; + if (rem > 0) // 1 or 2 digits remaining + bb.appendBits(parseInt(digits.substring(i), 10), rem * 3 + 1); + return new QrSegment(QrSegment_Mode.NUMERIC, digits.length, bb); + } + + + // Returns a segment representing the given text string encoded in alphanumeric mode. + // The characters allowed are: 0 to 9, A to Z (uppercase only), space, + // dollar, percent, asterisk, plus, hyphen, period, slash, colon. + public static makeAlphanumeric(text: string): QrSegment { + if (!this.ALPHANUMERIC_REGEX.test(text)) + throw "String contains unencodable characters in alphanumeric mode"; + let bb = new BitBuffer(); + let i: int; + for (i = 0; i + 2 <= text.length; i += 2) { // Process groups of 2 + let temp: int = QrSegment.ALPHANUMERIC_CHARSET.indexOf(text.charAt(i)) * 45; + temp += QrSegment.ALPHANUMERIC_CHARSET.indexOf(text.charAt(i + 1)); + bb.appendBits(temp, 11); + } + if (i < text.length) // 1 character remaining + bb.appendBits(QrSegment.ALPHANUMERIC_CHARSET.indexOf(text.charAt(i)), 6); + return new QrSegment(QrSegment_Mode.ALPHANUMERIC, text.length, bb); + } + + + // Returns a new mutable list of zero or more segments to represent the given Unicode text string. + // The result may use various segment modes and switch modes to optimize the length of the bit stream. + public static makeSegments(text: string): Array { + // Select the most efficient segment encoding automatically + if (text == "") + return []; + else if (this.NUMERIC_REGEX.test(text)) + return [QrSegment.makeNumeric(text)]; + else if (this.ALPHANUMERIC_REGEX.test(text)) + return [QrSegment.makeAlphanumeric(text)]; + else + return [QrSegment.makeBytes(QrSegment.toUtf8ByteArray(text))]; + } + + + // Returns a segment representing an Extended Channel Interpretation + // (ECI) designator with the given assignment value. + public static makeEci(assignVal: int): QrSegment { + let bb = new BitBuffer(); + if (0 <= assignVal && assignVal < (1 << 7)) + bb.appendBits(assignVal, 8); + else if ((1 << 7) <= assignVal && assignVal < (1 << 14)) { + bb.appendBits(2, 2); + bb.appendBits(assignVal, 14); + } else if ((1 << 14) <= assignVal && assignVal < 1000000) { + bb.appendBits(6, 3); + bb.appendBits(assignVal, 21); + } else + throw "ECI assignment value out of range"; + return new QrSegment(QrSegment_Mode.ECI, 0, bb); + } + + + /*-- Fields --*/ + + // The mode indicator for this segment. + public readonly mode: QrSegment_Mode; + + // The length of this segment's unencoded data, measured in characters. Always zero or positive. + public readonly numChars: int; + + private readonly bitData: Array; + + + /*-- Constructor --*/ + + public constructor(mode: QrSegment_Mode, numChars: int, bitData: Array) { + if (numChars < 0) + throw "Invalid argument"; + this.mode = mode; + this.numChars = numChars; + this.bitData = bitData.slice(); // Make defensive copy + } + + + /*-- Methods --*/ + + // Returns a copy of all bits, which is an array of 0s and 1s. + public getBits(): Array { + return this.bitData.slice(); // Make defensive copy + } + + + // Package-private helper function. + public static getTotalBits(segs: Array, version: int): int|null { + if (version < QrCode.MIN_VERSION || version > QrCode.MAX_VERSION) + throw "Version number out of range"; + let result: int = 0; + for (let i = 0; i < segs.length; i++) { + let seg: QrSegment = segs[i]; + let ccbits: int = seg.mode.numCharCountBits(version); + // Fail if segment length value doesn't fit in the length field's bit-width + if (seg.numChars >= (1 << ccbits)) + return null; + result += 4 + ccbits + seg.getBits().length; + } + return result; + } + + + // Returns a new array of bytes representing the given string encoded in UTF-8. + private static toUtf8ByteArray(str: string): Array { + str = encodeURI(str); + let result: Array = []; + for (let i = 0; i < str.length; i++) { + if (str.charAt(i) != "%") + result.push(str.charCodeAt(i)); + else { + result.push(parseInt(str.substr(i + 1, 2), 16)); + i += 2; + } + } + return result; + } + + + /*-- Constants --*/ + + // Can test whether a string is encodable in numeric mode (such as by using QrSegment.makeNumeric()). + public static get NUMERIC_REGEX(): RegExp { + return /^[0-9]*$/; + } + + // Can test whether a string is encodable in alphanumeric mode (such as by using QrSegment.makeAlphanumeric()). + public static get ALPHANUMERIC_REGEX(): RegExp { + return /^[A-Z0-9 $%*+.\/:-]*$/; + } + + // The set of all legal characters in alphanumeric mode, where each character value maps to the index in the string. + private static get ALPHANUMERIC_CHARSET(): string { + return "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:"; + } + + } + + + + /*---- Public helper enumeration ----*/ + + /* + * Represents the mode field of a segment. Immutable. + */ + export class QrSegment_Mode { + + /*-- Constants --*/ + + public static get NUMERIC () { return new QrSegment_Mode(0x1, [10, 12, 14]); } + public static get ALPHANUMERIC() { return new QrSegment_Mode(0x2, [ 9, 11, 13]); } + public static get BYTE () { return new QrSegment_Mode(0x4, [ 8, 16, 16]); } + public static get KANJI () { return new QrSegment_Mode(0x8, [ 8, 10, 12]); } + public static get ECI () { return new QrSegment_Mode(0x7, [ 0, 0, 0]); } + + + /*-- Fields --*/ + + // An unsigned 4-bit integer value (range 0 to 15) representing the mode indicator bits for this mode object. + public readonly modeBits: int; + + private readonly numBitsCharCount: [int,int,int]; + + + /*-- Constructor --*/ + + private constructor(mode: int, ccbits: [int,int,int]) { + this.modeBits = mode; + this.numBitsCharCount = ccbits; + } + + + /*-- Method --*/ + + // (Package-private) Returns the bit width of the segment character count field for this mode object at the given version number. + public numCharCountBits(ver: int): int { + if ( 1 <= ver && ver <= 9) return this.numBitsCharCount[0]; + else if (10 <= ver && ver <= 26) return this.numBitsCharCount[1]; + else if (27 <= ver && ver <= 40) return this.numBitsCharCount[2]; + else throw "Version number out of range"; + } + + } + + + + /*---- Private helper classes ----*/ + + /* + * Computes the Reed-Solomon error correction codewords for a sequence of data codewords + * at a given degree. Objects are immutable, and the state only depends on the degree. + * This class exists because each data block in a QR Code shares the same the divisor polynomial. + */ + class ReedSolomonGenerator { + + // Coefficients of the divisor polynomial, stored from highest to lowest power, excluding the leading term which + // is always 1. For example the polynomial x^3 + 255x^2 + 8x + 93 is stored as the uint8 array {255, 8, 93}. + private readonly coefficients: Array = []; + + + // Creates a Reed-Solomon ECC generator for the given degree. This could be implemented + // as a lookup table over all possible parameter values, instead of as an algorithm. + public constructor(degree: int) { + if (degree < 1 || degree > 255) + throw "Degree out of range"; + let coefs = this.coefficients; + + // Start with the monomial x^0 + for (let i = 0; i < degree - 1; i++) + coefs.push(0); + coefs.push(1); + + // Compute the product polynomial (x - r^0) * (x - r^1) * (x - r^2) * ... * (x - r^{degree-1}), + // drop the highest term, and store the rest of the coefficients in order of descending powers. + // Note that r = 0x02, which is a generator element of this field GF(2^8/0x11D). + let root = 1; + for (let i = 0; i < degree; i++) { + // Multiply the current product by (x - r^i) + for (let j = 0; j < coefs.length; j++) { + coefs[j] = ReedSolomonGenerator.multiply(coefs[j], root); + if (j + 1 < coefs.length) + coefs[j] ^= coefs[j + 1]; + } + root = ReedSolomonGenerator.multiply(root, 0x02); + } + } + + + // Computes and returns the Reed-Solomon error correction codewords for the given + // sequence of data codewords. The returned object is always a new byte array. + // This method does not alter this object's state (because it is immutable). + public getRemainder(data: Array): Array { + // Compute the remainder by performing polynomial division + let result: Array = this.coefficients.map(_ => 0); + data.forEach((b: byte) => { + let factor: byte = b ^ (result.shift() as int); + result.push(0); + for (let i = 0; i < result.length; i++) + result[i] ^= ReedSolomonGenerator.multiply(this.coefficients[i], factor); + }); + return result; + } + + + // Returns the product of the two given field elements modulo GF(2^8/0x11D). The arguments and result + // are unsigned 8-bit integers. This could be implemented as a lookup table of 256*256 entries of uint8. + private static multiply(x: byte, y: byte): byte { + if (x >>> 8 != 0 || y >>> 8 != 0) + throw "Byte out of range"; + // Russian peasant multiplication + let z: int = 0; + for (let i = 7; i >= 0; i--) { + z = (z << 1) ^ ((z >>> 7) * 0x11D); + z ^= ((y >>> i) & 1) * x; + } + if (z >>> 8 != 0) + throw "Assertion error"; + return z as byte; + } + + } + + + + /* + * An appendable sequence of bits. The implicit constructor creates an empty bit buffer (length 0). + */ + class BitBuffer extends Array { + + // Packs this buffer's bits into bytes in big endian, + // padding with '0' bit values, and returns the new array. + public getBytes(): Array { + let result: Array = []; + while (result.length * 8 < this.length) + result.push(0); + this.forEach((b: bit, i: int) => + result[i >>> 3] |= b << (7 - (i & 7))); + return result; + } + + + // Appends the given number of low bits of the given + // value to this sequence. Requires 0 <= val < 2^len. + public appendBits(val: int, len: int): void { + if (len < 0 || len > 31 || val >>> len != 0) + throw "Value out of range"; + for (let i = len - 1; i >= 0; i--) // Append bit by bit + this.push((val >>> i) & 1); + } + + } + +}