Add QR Code display support

Add a component to support QR Code display required for
different types of provisioning.

docs/en/COPYRIGHT.rst

@@ -67,6 +67,8 @@ These third party libraries can be included into the application (firmware) prod
 
 * :component_file:` TLSF allocator <heap/heap_tlsf.c>` Two Level Segregated Fit memory allocator, Copyright (c) 2006-2016, Matthew Conte, and licensed under the BSD license.
 
+* `qrcode`_ QR Code generator library Copyright (c) Project Nayuki, is licensed under MIT license.
+
 Build Tools
 -----------
 
@@ -179,3 +181,4 @@ Copyright (C) 2011, ChaN, all right reserved.
 .. _sphinx_idf_theme: https://github.com/espressif/sphinx_idf_theme
 .. _sphinx_rtd_theme: https://github.com/readthedocs/sphinx_rtd_theme
 .. _cryptoauthlib: https://github.com/MicrochipTech/cryptoauthlib
+.. _qrcode: https://github.com/nayuki/QR-Code-generator

examples/common_components/qrcode/CMakeLists.txt

@@ -0,0 +1,5 @@
+idf_component_register(SRCS "esp_qrcode_main.c" "esp_qrcode_wrapper.c" "qrcodegen.c"
+                       INCLUDE_DIRS "include"
+                       REQUIRES
+                       PRIV_REQUIRES )
+

examples/common_components/qrcode/esp_qrcode_main.c

@@ -0,0 +1,114 @@
+// Copyright 2019 Espressif Systems (Shanghai) PTE LTD
+//
+// 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.
+
+#include <stdio.h>
+#include <esp_err.h>
+
+#include "qrcodegen.h"
+#include "qrcode.h"
+
+static const char *lt[] = {
+    /* 0 */ "  ",
+    /* 1 */ "\u2580 ",
+    /* 2 */ " \u2580",
+    /* 3 */ "\u2580\u2580",
+    /* 4 */ "\u2584 ",
+    /* 5 */ "\u2588 ",
+    /* 6 */ "\u2584\u2580",
+    /* 7 */ "\u2588\u2580",
+    /* 8 */ " \u2584",
+    /* 9 */ "\u2580\u2584",
+    /* 10 */ " \u2588",
+    /* 11 */ "\u2580\u2588",
+    /* 12 */ "\u2584\u2584",
+    /* 13 */ "\u2588\u2584",
+    /* 14 */ "\u2584\u2588",
+    /* 15 */ "\u2588\u2588",
+};
+
+void esp_qrcode_print_console(esp_qrcode_handle_t qrcode)
+{
+    int size = qrcodegen_getSize(qrcode);
+    int border = 2;
+    unsigned char num = 0;
+
+    for (int y = -border; y < size + border; y+=2) {
+        for (int x = -border; x < size + border; x+=2) {
+            num = 0;
+            if (qrcodegen_getModule(qrcode, x, y)) {
+                num |= 1 << 0;
+            }
+            if ((x < size + border) && qrcodegen_getModule(qrcode, x+1, y)) {
+                num |= 1 << 1;
+            }
+            if ((y < size + border) && qrcodegen_getModule(qrcode, x, y+1)) {
+                num |= 1 << 2;
+            }
+            if ((x < size + border) && (y < size + border) && qrcodegen_getModule(qrcode, x+1, y+1)) {
+                num |= 1 << 3;
+            }
+            printf("%s", lt[num]);
+        }
+        printf("\n");
+    }
+    printf("\n");
+}
+
+esp_err_t esp_qrcode_generate(esp_qrcode_config_t *cfg, const char *text)
+{
+	enum qrcodegen_Ecc ecc_lvl;
+    uint8_t *qrcode, *tempbuf;
+    esp_err_t err = ESP_FAIL;
+
+    qrcode = calloc(1, qrcodegen_BUFFER_LEN_FOR_VERSION(cfg->max_qrcode_version));
+    if (!qrcode)
+        return ESP_ERR_NO_MEM;
+
+    tempbuf = calloc(1, qrcodegen_BUFFER_LEN_FOR_VERSION(cfg->max_qrcode_version));
+    if (!tempbuf) {
+        free(qrcode);
+        return ESP_ERR_NO_MEM;
+    }
+
+    switch(cfg->qrcode_ecc_level) {
+        case ESP_QRCODE_ECC_LOW:
+            ecc_lvl = qrcodegen_Ecc_LOW;
+            break;
+        case ESP_QRCODE_ECC_MED:
+            ecc_lvl = qrcodegen_Ecc_MEDIUM;
+            break;
+        case ESP_QRCODE_ECC_QUART:
+            ecc_lvl = qrcodegen_Ecc_QUARTILE;
+            break;
+        case ESP_QRCODE_ECC_HIGH:
+            ecc_lvl = qrcodegen_Ecc_HIGH;
+            break;
+        default:
+            ecc_lvl = qrcodegen_Ecc_LOW;
+            break;
+    }
+
+	// Make and print the QR Code symbol
+	bool ok = qrcodegen_encodeText(text, tempbuf, qrcode, ecc_lvl,
+		                           qrcodegen_VERSION_MIN, cfg->max_qrcode_version,
+                                   qrcodegen_Mask_AUTO, true);
+	if (ok && cfg->display_func) {
+		cfg->display_func((esp_qrcode_handle_t)qrcode);
+        err = ESP_OK;
+    }
+
+    free(qrcode);
+    free(tempbuf);
+    return err;
+}

examples/common_components/qrcode/esp_qrcode_wrapper.c

@@ -0,0 +1,29 @@
+// Copyright 2019 Espressif Systems (Shanghai) PTE LTD
+//
+// 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.
+
+#include <stdio.h>
+#include <esp_err.h>
+
+#include "qrcodegen.h"
+#include "qrcode.h"
+
+int esp_qrcode_get_size(esp_qrcode_handle_t qrcode)
+{
+    return qrcodegen_getSize(qrcode);
+}
+
+bool esp_qrcode_get_module(esp_qrcode_handle_t qrcode, int x, int y)
+{
+    return qrcodegen_getModule(qrcode, x, y);
+}

examples/common_components/qrcode/include/qrcode.h

@@ -0,0 +1,104 @@
+// Copyright 2019 Espressif Systems (Shanghai) PTE LTD
+//
+// 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.
+#pragma once
+
+#include <esp_err.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+  * @brief  QR Code handle used by the display function
+  */
+typedef const uint8_t * esp_qrcode_handle_t;
+
+/**
+  * @brief  QR Code configuration options
+  */
+typedef struct {
+    void (*display_func)(esp_qrcode_handle_t qrcode);   /**< Function called for displaying the QR Code after encoding is complete */
+    int max_qrcode_version;                             /**< Max QR Code Version to be used. Range: 2 - 40 */
+    int qrcode_ecc_level;                               /**< Error Correction Level for QR Code */
+} esp_qrcode_config_t;
+
+/**
+  * @brief  Error Correction Level in a QR Code Symbol
+  */
+enum {
+    ESP_QRCODE_ECC_LOW,     /**< QR Code Error Tolerance of 7% */
+    ESP_QRCODE_ECC_MED,     /**< QR Code Error Tolerance of 15% */
+    ESP_QRCODE_ECC_QUART,   /**< QR Code Error Tolerance of 25% */
+    ESP_QRCODE_ECC_HIGH     /**< QR Code Error Tolerance of 30% */
+};
+
+/**
+  * @brief  Encodes the given string into a QR Code and calls the display function
+  *
+  * @attention 1. Can successfully encode a UTF-8 string of up to 2953 bytes or an alphanumeric
+  *               string of up to 4296 characters or any digit string of up to 7089 characters
+  *
+  * @param  cfg   Configuration used for QR Code encoding.
+  * @param  text  String to encode into a QR Code.
+  *
+  * @return
+  *    - ESP_OK: succeed
+  *    - ESP_FAIL: Failed to encode string into a QR Code
+  *    - ESP_ERR_NO_MEM: Failed to allocate buffer for given max_qrcode_version
+  */
+esp_err_t esp_qrcode_generate(esp_qrcode_config_t *cfg, const char *text);
+
+/**
+  * @brief  Displays QR Code on the console
+  *
+  * @param  qrcode  QR Code handle used by the display function.
+  */
+void esp_qrcode_print_console(esp_qrcode_handle_t qrcode);
+
+/**
+  * @brief  Returns the side length of the given QR Code
+  *
+  * @param  qrcode  QR Code handle used by the display function.
+  *
+  * @return
+  *    - val[21, 177]: Side length of QR Code
+  */
+int esp_qrcode_get_size(esp_qrcode_handle_t qrcode);
+
+/**
+  * @brief  Returns the Pixel value for the given coordinates
+  *         False indicates White and True indicates Black
+  *
+  * @attention 1. Coordinates for top left corner are (x=0, y=0)
+  * @attention 2. For out of bound coordinates false (White) is returned
+  *
+  * @param  qrcode  QR Code handle used by the display function.
+  * @param  x  X-Coordinate of QR Code module
+  * @param  y  Y-Coordinate of QR Code module
+  *
+  * @return
+  *    - true: (x, y) Pixel is Black
+  *    - false: (x, y) Pixel is White
+  */
+bool esp_qrcode_get_module(esp_qrcode_handle_t qrcode, int x, int y);
+
+#define ESP_QRCODE_CONFIG_DEFAULT() (esp_qrcode_config_t) { \
+    .display_func = esp_qrcode_print_console, \
+    .qrcode_ecc_level = ESP_QRCODE_ECC_LOW, \
+    .max_qrcode_version = 10, \
+} \
+
+#ifdef __cplusplus
+}
+#endif

examples/common_components/qrcode/qrcodegen.c

@@ -0,0 +1,1022 @@
+/*
+ * QR Code generator library (C)
+ *
+ * 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.
+ */
+
+#include <assert.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+#include "qrcodegen.h"
+
+#ifndef QRCODEGEN_TEST
+	#define testable static  // Keep functions private
+#else
+	#define testable  // Expose private functions
+#endif
+
+
+/*---- Forward declarations for private functions ----*/
+
+// Regarding all public and private functions defined in this source file:
+// - They require all pointer/array arguments to be not null unless the array length is zero.
+// - They only read input scalar/array arguments, write to output pointer/array
+//   arguments, and return scalar values; they are "pure" functions.
+// - They don't read mutable global variables or write to any global variables.
+// - They don't perform I/O, read the clock, print to console, etc.
+// - They allocate a small and constant amount of stack memory.
+// - They don't allocate or free any memory on the heap.
+// - They don't recurse or mutually recurse. All the code
+//   could be inlined into the top-level public functions.
+// - They run in at most quadratic time with respect to input arguments.
+//   Most functions run in linear time, and some in constant time.
+//   There are no unbounded loops or non-obvious termination conditions.
+// - They are completely thread-safe if the caller does not give the
+//   same writable buffer to concurrent calls to these functions.
+
+testable void appendBitsToBuffer(unsigned int val, int numBits, uint8_t buffer[], int *bitLen);
+
+testable void addEccAndInterleave(uint8_t data[], int version, enum qrcodegen_Ecc ecl, uint8_t result[]);
+testable int getNumDataCodewords(int version, enum qrcodegen_Ecc ecl);
+testable int getNumRawDataModules(int ver);
+
+testable void reedSolomonComputeDivisor(int degree, uint8_t result[]);
+testable void reedSolomonComputeRemainder(const uint8_t data[], int dataLen,
+	const uint8_t generator[], int degree, uint8_t result[]);
+testable uint8_t reedSolomonMultiply(uint8_t x, uint8_t y);
+
+testable void initializeFunctionModules(int version, uint8_t qrcode[]);
+static void drawWhiteFunctionModules(uint8_t qrcode[], int version);
+static void drawFormatBits(enum qrcodegen_Ecc ecl, enum qrcodegen_Mask mask, uint8_t qrcode[]);
+testable int getAlignmentPatternPositions(int version, uint8_t result[7]);
+static void fillRectangle(int left, int top, int width, int height, uint8_t qrcode[]);
+
+static void drawCodewords(const uint8_t data[], int dataLen, uint8_t qrcode[]);
+static void applyMask(const uint8_t functionModules[], uint8_t qrcode[], enum qrcodegen_Mask mask);
+static long getPenaltyScore(const uint8_t qrcode[]);
+static int finderPenaltyCountPatterns(const int runHistory[7], int qrsize);
+static int finderPenaltyTerminateAndCount(bool currentRunColor, int currentRunLength, int runHistory[7], int qrsize);
+static void finderPenaltyAddHistory(int currentRunLength, int runHistory[7]);
+
+testable bool getModule(const uint8_t qrcode[], int x, int y);
+testable void setModule(uint8_t qrcode[], int x, int y, bool isBlack);
+testable void setModuleBounded(uint8_t qrcode[], int x, int y, bool isBlack);
+static bool getBit(int x, int i);
+
+testable int calcSegmentBitLength(enum qrcodegen_Mode mode, size_t numChars);
+testable int getTotalBits(const struct qrcodegen_Segment segs[], size_t len, int version);
+static int numCharCountBits(enum qrcodegen_Mode mode, int version);
+
+
+
+/*---- Private tables of constants ----*/
+
+// The set of all legal characters in alphanumeric mode, where each character
+// value maps to the index in the string. For checking text and encoding segments.
+static const char *ALPHANUMERIC_CHARSET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:";
+
+// For generating error correction codes.
+testable const int8_t ECC_CODEWORDS_PER_BLOCK[4][41] = {
+	// 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
+};
+
+#define qrcodegen_REED_SOLOMON_DEGREE_MAX 30  // Based on the table above
+
+// For generating error correction codes.
+testable const int8_t NUM_ERROR_CORRECTION_BLOCKS[4][41] = {
+	// 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
+};
+
+// For automatic mask pattern selection.
+static const int PENALTY_N1 =  3;
+static const int PENALTY_N2 =  3;
+static const int PENALTY_N3 = 40;
+static const int PENALTY_N4 = 10;
+
+
+
+/*---- High-level QR Code encoding functions ----*/
+
+// Public function - see documentation comment in header file.
+bool qrcodegen_encodeText(const char *text, uint8_t tempBuffer[], uint8_t qrcode[],
+		enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl) {
+
+	size_t textLen = strlen(text);
+	if (textLen == 0)
+		return qrcodegen_encodeSegmentsAdvanced(NULL, 0, ecl, minVersion, maxVersion, mask, boostEcl, tempBuffer, qrcode);
+	size_t bufLen = (size_t)qrcodegen_BUFFER_LEN_FOR_VERSION(maxVersion);
+
+	struct qrcodegen_Segment seg;
+	if (qrcodegen_isNumeric(text)) {
+		if (qrcodegen_calcSegmentBufferSize(qrcodegen_Mode_NUMERIC, textLen) > bufLen)
+			goto fail;
+		seg = qrcodegen_makeNumeric(text, tempBuffer);
+	} else if (qrcodegen_isAlphanumeric(text)) {
+		if (qrcodegen_calcSegmentBufferSize(qrcodegen_Mode_ALPHANUMERIC, textLen) > bufLen)
+			goto fail;
+		seg = qrcodegen_makeAlphanumeric(text, tempBuffer);
+	} else {
+		if (textLen > bufLen)
+			goto fail;
+		for (size_t i = 0; i < textLen; i++)
+			tempBuffer[i] = (uint8_t)text[i];
+		seg.mode = qrcodegen_Mode_BYTE;
+		seg.bitLength = calcSegmentBitLength(seg.mode, textLen);
+		if (seg.bitLength == -1)
+			goto fail;
+		seg.numChars = (int)textLen;
+		seg.data = tempBuffer;
+	}
+	return qrcodegen_encodeSegmentsAdvanced(&seg, 1, ecl, minVersion, maxVersion, mask, boostEcl, tempBuffer, qrcode);
+
+fail:
+	qrcode[0] = 0;  // Set size to invalid value for safety
+	return false;
+}
+
+
+// Public function - see documentation comment in header file.
+bool qrcodegen_encodeBinary(uint8_t dataAndTemp[], size_t dataLen, uint8_t qrcode[],
+		enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl) {
+
+	struct qrcodegen_Segment seg;
+	seg.mode = qrcodegen_Mode_BYTE;
+	seg.bitLength = calcSegmentBitLength(seg.mode, dataLen);
+	if (seg.bitLength == -1) {
+		qrcode[0] = 0;  // Set size to invalid value for safety
+		return false;
+	}
+	seg.numChars = (int)dataLen;
+	seg.data = dataAndTemp;
+	return qrcodegen_encodeSegmentsAdvanced(&seg, 1, ecl, minVersion, maxVersion, mask, boostEcl, dataAndTemp, qrcode);
+}
+
+
+// Appends the given number of low-order bits of the given value to the given byte-based
+// bit buffer, increasing the bit length. Requires 0 <= numBits <= 16 and val < 2^numBits.
+testable void appendBitsToBuffer(unsigned int val, int numBits, uint8_t buffer[], int *bitLen) {
+	assert(0 <= numBits && numBits <= 16 && (unsigned long)val >> numBits == 0);
+	for (int i = numBits - 1; i >= 0; i--, (*bitLen)++)
+		buffer[*bitLen >> 3] |= ((val >> i) & 1) << (7 - (*bitLen & 7));
+}
+
+
+
+/*---- Low-level QR Code encoding functions ----*/
+
+// Public function - see documentation comment in header file.
+bool qrcodegen_encodeSegments(const struct qrcodegen_Segment segs[], size_t len,
+		enum qrcodegen_Ecc ecl, uint8_t tempBuffer[], uint8_t qrcode[]) {
+	return qrcodegen_encodeSegmentsAdvanced(segs, len, ecl,
+		qrcodegen_VERSION_MIN, qrcodegen_VERSION_MAX, qrcodegen_Mask_AUTO, true, tempBuffer, qrcode);
+}
+
+
+// Public function - see documentation comment in header file.
+bool qrcodegen_encodeSegmentsAdvanced(const struct qrcodegen_Segment segs[], size_t len, enum qrcodegen_Ecc ecl,
+		int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl, uint8_t tempBuffer[], uint8_t qrcode[]) {
+	assert(segs != NULL || len == 0);
+	assert(qrcodegen_VERSION_MIN <= minVersion && minVersion <= maxVersion && maxVersion <= qrcodegen_VERSION_MAX);
+	assert(0 <= (int)ecl && (int)ecl <= 3 && -1 <= (int)mask && (int)mask <= 7);
+
+	// Find the minimal version number to use
+	int version, dataUsedBits;
+	for (version = minVersion; ; version++) {
+		int dataCapacityBits = getNumDataCodewords(version, ecl) * 8;  // Number of data bits available
+		dataUsedBits = getTotalBits(segs, len, version);
+		if (dataUsedBits != -1 && dataUsedBits <= dataCapacityBits)
+			break;  // This version number is found to be suitable
+		if (version >= maxVersion) {  // All versions in the range could not fit the given data
+			qrcode[0] = 0;  // Set size to invalid value for safety
+			return false;
+		}
+	}
+	assert(dataUsedBits != -1);
+
+	// Increase the error correction level while the data still fits in the current version number
+	for (int i = (int)qrcodegen_Ecc_MEDIUM; i <= (int)qrcodegen_Ecc_HIGH; i++) {  // From low to high
+		if (boostEcl && dataUsedBits <= getNumDataCodewords(version, (enum qrcodegen_Ecc)i) * 8)
+			ecl = (enum qrcodegen_Ecc)i;
+	}
+
+	// Concatenate all segments to create the data bit string
+	memset(qrcode, 0, (size_t)qrcodegen_BUFFER_LEN_FOR_VERSION(version) * sizeof(qrcode[0]));
+	int bitLen = 0;
+	for (size_t i = 0; i < len; i++) {
+		const struct qrcodegen_Segment *seg = &segs[i];
+		appendBitsToBuffer((unsigned int)seg->mode, 4, qrcode, &bitLen);
+		appendBitsToBuffer((unsigned int)seg->numChars, numCharCountBits(seg->mode, version), qrcode, &bitLen);
+		for (int j = 0; j < seg->bitLength; j++) {
+			int bit = (seg->data[j >> 3] >> (7 - (j & 7))) & 1;
+			appendBitsToBuffer((unsigned int)bit, 1, qrcode, &bitLen);
+		}
+	}
+	assert(bitLen == dataUsedBits);
+
+	// Add terminator and pad up to a byte if applicable
+	int dataCapacityBits = getNumDataCodewords(version, ecl) * 8;
+	assert(bitLen <= dataCapacityBits);
+	int terminatorBits = dataCapacityBits - bitLen;
+	if (terminatorBits > 4)
+		terminatorBits = 4;
+	appendBitsToBuffer(0, terminatorBits, qrcode, &bitLen);
+	appendBitsToBuffer(0, (8 - bitLen % 8) % 8, qrcode, &bitLen);
+	assert(bitLen % 8 == 0);
+
+	// Pad with alternating bytes until data capacity is reached
+	for (uint8_t padByte = 0xEC; bitLen < dataCapacityBits; padByte ^= 0xEC ^ 0x11)
+		appendBitsToBuffer(padByte, 8, qrcode, &bitLen);
+
+	// Draw function and data codeword modules
+	addEccAndInterleave(qrcode, version, ecl, tempBuffer);
+	initializeFunctionModules(version, qrcode);
+	drawCodewords(tempBuffer, getNumRawDataModules(version) / 8, qrcode);
+	drawWhiteFunctionModules(qrcode, version);
+	initializeFunctionModules(version, tempBuffer);
+
+	// Handle masking
+	if (mask == qrcodegen_Mask_AUTO) {  // Automatically choose best mask
+		long minPenalty = LONG_MAX;
+		for (int i = 0; i < 8; i++) {
+			enum qrcodegen_Mask msk = (enum qrcodegen_Mask)i;
+			applyMask(tempBuffer, qrcode, msk);
+			drawFormatBits(ecl, msk, qrcode);
+			long penalty = getPenaltyScore(qrcode);
+			if (penalty < minPenalty) {
+				mask = msk;
+				minPenalty = penalty;
+			}
+			applyMask(tempBuffer, qrcode, msk);  // Undoes the mask due to XOR
+		}
+	}
+	assert(0 <= (int)mask && (int)mask <= 7);
+	applyMask(tempBuffer, qrcode, mask);
+	drawFormatBits(ecl, mask, qrcode);
+	return true;
+}
+
+
+
+/*---- Error correction code generation functions ----*/
+
+// Appends error correction bytes to each block of the given data array, then interleaves
+// bytes from the blocks and stores them in the result array. data[0 : dataLen] contains
+// the input data. data[dataLen : rawCodewords] is used as a temporary work area and will
+// be clobbered by this function. The final answer is stored in result[0 : rawCodewords].
+testable void addEccAndInterleave(uint8_t data[], int version, enum qrcodegen_Ecc ecl, uint8_t result[]) {
+	// Calculate parameter numbers
+	assert(0 <= (int)ecl && (int)ecl < 4 && qrcodegen_VERSION_MIN <= version && version <= qrcodegen_VERSION_MAX);
+	int numBlocks = NUM_ERROR_CORRECTION_BLOCKS[(int)ecl][version];
+	int blockEccLen = ECC_CODEWORDS_PER_BLOCK  [(int)ecl][version];
+	int rawCodewords = getNumRawDataModules(version) / 8;
+	int dataLen = getNumDataCodewords(version, ecl);
+	int numShortBlocks = numBlocks - rawCodewords % numBlocks;
+	int shortBlockDataLen = rawCodewords / numBlocks - blockEccLen;
+
+	// Split data into blocks, calculate ECC, and interleave
+	// (not concatenate) the bytes into a single sequence
+	uint8_t rsdiv[qrcodegen_REED_SOLOMON_DEGREE_MAX];
+	reedSolomonComputeDivisor(blockEccLen, rsdiv);
+	const uint8_t *dat = data;
+	for (int i = 0; i < numBlocks; i++) {
+		int datLen = shortBlockDataLen + (i < numShortBlocks ? 0 : 1);
+		uint8_t *ecc = &data[dataLen];  // Temporary storage
+		reedSolomonComputeRemainder(dat, datLen, rsdiv, blockEccLen, ecc);
+		for (int j = 0, k = i; j < datLen; j++, k += numBlocks) {  // Copy data
+			if (j == shortBlockDataLen)
+				k -= numShortBlocks;
+			result[k] = dat[j];
+		}
+		for (int j = 0, k = dataLen + i; j < blockEccLen; j++, k += numBlocks)  // Copy ECC
+			result[k] = ecc[j];
+		dat += datLen;
+	}
+}
+
+
+// Returns the number of 8-bit codewords that can be used for storing data (not ECC),
+// for the given version number and error correction level. The result is in the range [9, 2956].
+testable int getNumDataCodewords(int version, enum qrcodegen_Ecc ecl) {
+	int v = version, e = (int)ecl;
+	assert(0 <= e && e < 4);
+	return getNumRawDataModules(v) / 8
+		- ECC_CODEWORDS_PER_BLOCK    [e][v]
+		* NUM_ERROR_CORRECTION_BLOCKS[e][v];
+}
+
+
+// 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.
+testable int getNumRawDataModules(int ver) {
+	assert(qrcodegen_VERSION_MIN <= ver && ver <= qrcodegen_VERSION_MAX);
+	int result = (16 * ver + 128) * ver + 64;
+	if (ver >= 2) {
+		int numAlign = ver / 7 + 2;
+		result -= (25 * numAlign - 10) * numAlign - 55;
+		if (ver >= 7)
+			result -= 36;
+	}
+	assert(208 <= result && result <= 29648);
+	return result;
+}
+
+
+
+/*---- Reed-Solomon ECC generator functions ----*/
+
+// Computes a Reed-Solomon ECC generator polynomial for the given degree, storing in result[0 : degree].
+// This could be implemented as a lookup table over all possible parameter values, instead of as an algorithm.
+testable void reedSolomonComputeDivisor(int degree, uint8_t result[]) {
+	assert(1 <= degree && degree <= qrcodegen_REED_SOLOMON_DEGREE_MAX);
+	// Polynomial coefficients are 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}.
+	memset(result, 0, (size_t)degree * sizeof(result[0]));
+	result[degree - 1] = 1;  // Start off with the monomial x^0
+
+	// Compute the product polynomial (x - r^0) * (x - r^1) * (x - r^2) * ... * (x - r^{degree-1}),
+	// drop the highest monomial term which is always 1x^degree.
+	// Note that r = 0x02, which is a generator element of this field GF(2^8/0x11D).
+	uint8_t root = 1;
+	for (int i = 0; i < degree; i++) {
+		// Multiply the current product by (x - r^i)
+		for (int j = 0; j < degree; j++) {
+			result[j] = reedSolomonMultiply(result[j], root);
+			if (j + 1 < degree)
+				result[j] ^= result[j + 1];
+		}
+		root = reedSolomonMultiply(root, 0x02);
+	}
+}
+
+
+// Computes the Reed-Solomon error correction codeword for the given data and divisor polynomials.
+// The remainder when data[0 : dataLen] is divided by divisor[0 : degree] is stored in result[0 : degree].
+// All polynomials are in big endian, and the generator has an implicit leading 1 term.
+testable void reedSolomonComputeRemainder(const uint8_t data[], int dataLen,
+		const uint8_t generator[], int degree, uint8_t result[]) {
+	assert(1 <= degree && degree <= qrcodegen_REED_SOLOMON_DEGREE_MAX);
+	memset(result, 0, (size_t)degree * sizeof(result[0]));
+	for (int i = 0; i < dataLen; i++) {  // Polynomial division
+		uint8_t factor = data[i] ^ result[0];
+		memmove(&result[0], &result[1], (size_t)(degree - 1) * sizeof(result[0]));
+		result[degree - 1] = 0;
+		for (int j = 0; j < degree; j++)
+			result[j] ^= reedSolomonMultiply(generator[j], factor);
+	}
+}
+
+#undef qrcodegen_REED_SOLOMON_DEGREE_MAX
+
+
+// Returns the product of the two given field elements modulo GF(2^8/0x11D).
+// All inputs are valid. This could be implemented as a 256*256 lookup table.
+testable uint8_t reedSolomonMultiply(uint8_t x, uint8_t y) {
+	// Russian peasant multiplication
+	uint8_t z = 0;
+	for (int i = 7; i >= 0; i--) {
+		z = (uint8_t)((z << 1) ^ ((z >> 7) * 0x11D));
+		z ^= ((y >> i) & 1) * x;
+	}
+	return z;
+}
+
+
+
+/*---- Drawing function modules ----*/
+
+// Clears the given QR Code grid with white modules for the given
+// version's size, then marks every function module as black.
+testable void initializeFunctionModules(int version, uint8_t qrcode[]) {
+	// Initialize QR Code
+	int qrsize = version * 4 + 17;
+	memset(qrcode, 0, (size_t)((qrsize * qrsize + 7) / 8 + 1) * sizeof(qrcode[0]));
+	qrcode[0] = (uint8_t)qrsize;
+
+	// Fill horizontal and vertical timing patterns
+	fillRectangle(6, 0, 1, qrsize, qrcode);
+	fillRectangle(0, 6, qrsize, 1, qrcode);
+
+	// Fill 3 finder patterns (all corners except bottom right) and format bits
+	fillRectangle(0, 0, 9, 9, qrcode);
+	fillRectangle(qrsize - 8, 0, 8, 9, qrcode);
+	fillRectangle(0, qrsize - 8, 9, 8, qrcode);
+
+	// Fill numerous alignment patterns
+	uint8_t alignPatPos[7];
+	int numAlign = getAlignmentPatternPositions(version, alignPatPos);
+	for (int i = 0; i < numAlign; i++) {
+		for (int j = 0; j < numAlign; j++) {
+			// Don't draw on the three finder corners
+			if (!((i == 0 && j == 0) || (i == 0 && j == numAlign - 1) || (i == numAlign - 1 && j == 0)))
+				fillRectangle(alignPatPos[i] - 2, alignPatPos[j] - 2, 5, 5, qrcode);
+		}
+	}
+
+	// Fill version blocks
+	if (version >= 7) {
+		fillRectangle(qrsize - 11, 0, 3, 6, qrcode);
+		fillRectangle(0, qrsize - 11, 6, 3, qrcode);
+	}
+}
+
+
+// Draws white function modules and possibly some black modules onto the given QR Code, without changing
+// non-function modules. This does not draw the format bits. This requires all function modules to be previously
+// marked black (namely by initializeFunctionModules()), because this may skip redrawing black function modules.
+static void drawWhiteFunctionModules(uint8_t qrcode[], int version) {
+	// Draw horizontal and vertical timing patterns
+	int qrsize = qrcodegen_getSize(qrcode);
+	for (int i = 7; i < qrsize - 7; i += 2) {
+		setModule(qrcode, 6, i, false);
+		setModule(qrcode, i, 6, false);
+	}
+
+	// Draw 3 finder patterns (all corners except bottom right; overwrites some timing modules)
+	for (int dy = -4; dy <= 4; dy++) {
+		for (int dx = -4; dx <= 4; dx++) {
+			int dist = abs(dx);
+			if (abs(dy) > dist)
+				dist = abs(dy);
+			if (dist == 2 || dist == 4) {
+				setModuleBounded(qrcode, 3 + dx, 3 + dy, false);
+				setModuleBounded(qrcode, qrsize - 4 + dx, 3 + dy, false);
+				setModuleBounded(qrcode, 3 + dx, qrsize - 4 + dy, false);
+			}
+		}
+	}
+
+	// Draw numerous alignment patterns
+	uint8_t alignPatPos[7];
+	int numAlign = getAlignmentPatternPositions(version, alignPatPos);
+	for (int i = 0; i < numAlign; i++) {
+		for (int j = 0; j < numAlign; j++) {
+			if ((i == 0 && j == 0) || (i == 0 && j == numAlign - 1) || (i == numAlign - 1 && j == 0))
+				continue;  // Don't draw on the three finder corners
+			for (int dy = -1; dy <= 1; dy++) {
+				for (int dx = -1; dx <= 1; dx++)
+					setModule(qrcode, alignPatPos[i] + dx, alignPatPos[j] + dy, dx == 0 && dy == 0);
+			}
+		}
+	}
+
+	// Draw version blocks
+	if (version >= 7) {
+		// Calculate error correction code and pack bits
+		int rem = version;  // version is uint6, in the range [7, 40]
+		for (int i = 0; i < 12; i++)
+			rem = (rem << 1) ^ ((rem >> 11) * 0x1F25);
+		long bits = (long)version << 12 | rem;  // uint18
+		assert(bits >> 18 == 0);
+
+		// Draw two copies
+		for (int i = 0; i < 6; i++) {
+			for (int j = 0; j < 3; j++) {
+				int k = qrsize - 11 + j;
+				setModule(qrcode, k, i, (bits & 1) != 0);
+				setModule(qrcode, i, k, (bits & 1) != 0);
+				bits >>= 1;
+			}
+		}
+	}
+}
+
+
+// Draws two copies of the format bits (with its own error correction code) based
+// on the given mask and error correction level. This always draws all modules of
+// the format bits, unlike drawWhiteFunctionModules() which might skip black modules.
+static void drawFormatBits(enum qrcodegen_Ecc ecl, enum qrcodegen_Mask mask, uint8_t qrcode[]) {
+	// Calculate error correction code and pack bits
+	assert(0 <= (int)mask && (int)mask <= 7);
+	static const int table[] = {1, 0, 3, 2};
+	int data = table[(int)ecl] << 3 | (int)mask;  // errCorrLvl is uint2, mask is uint3
+	int rem = data;
+	for (int i = 0; i < 10; i++)
+		rem = (rem << 1) ^ ((rem >> 9) * 0x537);
+	int bits = (data << 10 | rem) ^ 0x5412;  // uint15
+	assert(bits >> 15 == 0);
+
+	// Draw first copy
+	for (int i = 0; i <= 5; i++)
+		setModule(qrcode, 8, i, getBit(bits, i));
+	setModule(qrcode, 8, 7, getBit(bits, 6));
+	setModule(qrcode, 8, 8, getBit(bits, 7));
+	setModule(qrcode, 7, 8, getBit(bits, 8));
+	for (int i = 9; i < 15; i++)
+		setModule(qrcode, 14 - i, 8, getBit(bits, i));
+
+	// Draw second copy
+	int qrsize = qrcodegen_getSize(qrcode);
+	for (int i = 0; i < 8; i++)
+		setModule(qrcode, qrsize - 1 - i, 8, getBit(bits, i));
+	for (int i = 8; i < 15; i++)
+		setModule(qrcode, 8, qrsize - 15 + i, getBit(bits, i));
+	setModule(qrcode, 8, qrsize - 8, true);  // Always black
+}
+
+
+// Calculates and stores an ascending list of positions of alignment patterns
+// for this version number, returning the length of the list (in the range [0,7]).
+// Each position is in the range [0,177), and are used on both the x and y axes.
+// This could be implemented as lookup table of 40 variable-length lists of unsigned bytes.
+testable int getAlignmentPatternPositions(int version, uint8_t result[7]) {
+	if (version == 1)
+		return 0;
+	int numAlign = version / 7 + 2;
+	int step = (version == 32) ? 26 :
+		(version*4 + numAlign*2 + 1) / (numAlign*2 - 2) * 2;
+	for (int i = numAlign - 1, pos = version * 4 + 10; i >= 1; i--, pos -= step)
+		result[i] = (uint8_t)pos;
+	result[0] = 6;
+	return numAlign;
+}
+
+
+// Sets every pixel in the range [left : left + width] * [top : top + height] to black.
+static void fillRectangle(int left, int top, int width, int height, uint8_t qrcode[]) {
+	for (int dy = 0; dy < height; dy++) {
+		for (int dx = 0; dx < width; dx++)
+			setModule(qrcode, left + dx, top + dy, true);
+	}
+}
+
+
+
+/*---- Drawing data modules and masking ----*/
+
+// Draws the raw codewords (including data and ECC) onto the given QR Code. This requires the initial state of
+// the QR Code to be black at function modules and white at codeword modules (including unused remainder bits).
+static void drawCodewords(const uint8_t data[], int dataLen, uint8_t qrcode[]) {
+	int qrsize = qrcodegen_getSize(qrcode);
+	int i = 0;  // Bit index into the data
+	// Do the funny zigzag scan
+	for (int right = qrsize - 1; right >= 1; right -= 2) {  // Index of right column in each column pair
+		if (right == 6)
+			right = 5;
+		for (int vert = 0; vert < qrsize; vert++) {  // Vertical counter
+			for (int j = 0; j < 2; j++) {
+				int x = right - j;  // Actual x coordinate
+				bool upward = ((right + 1) & 2) == 0;
+				int y = upward ? qrsize - 1 - vert : vert;  // Actual y coordinate
+				if (!getModule(qrcode, x, y) && i < dataLen * 8) {
+					bool black = getBit(data[i >> 3], 7 - (i & 7));
+					setModule(qrcode, x, y, black);
+					i++;
+				}
+				// If this QR Code has any remainder bits (0 to 7), they were assigned as
+				// 0/false/white by the constructor and are left unchanged by this method
+			}
+		}
+	}
+	assert(i == dataLen * 8);
+}
+
+
+// XORs the codeword modules in this QR Code with the given mask pattern.
+// The function modules must be marked and the codeword bits must be drawn
+// before masking. Due to the arithmetic of XOR, calling applyMask() with
+// the same mask value a second time will undo the mask. A final well-formed
+// QR Code needs exactly one (not zero, two, etc.) mask applied.
+static void applyMask(const uint8_t functionModules[], uint8_t qrcode[], enum qrcodegen_Mask mask) {
+	assert(0 <= (int)mask && (int)mask <= 7);  // Disallows qrcodegen_Mask_AUTO
+	int qrsize = qrcodegen_getSize(qrcode);
+	for (int y = 0; y < qrsize; y++) {
+		for (int x = 0; x < qrsize; x++) {
+			if (getModule(functionModules, x, y))
+				continue;
+			bool invert;
+			switch ((int)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 = (x / 3 + 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:  assert(false);  return;
+			}
+			bool val = getModule(qrcode, x, y);
+			setModule(qrcode, x, y, val ^ invert);
+		}
+	}
+}
+
+
+// Calculates and returns the penalty score based on state of the given QR Code's current modules.
+// This is used by the automatic mask choice algorithm to find the mask pattern that yields the lowest score.
+static long getPenaltyScore(const uint8_t qrcode[]) {
+	int qrsize = qrcodegen_getSize(qrcode);
+	long result = 0;
+
+	// Adjacent modules in row having same color, and finder-like patterns
+	for (int y = 0; y < qrsize; y++) {
+		bool runColor = false;
+		int runX = 0;
+		int runHistory[7] = {0};
+		int padRun = qrsize;  // Add white border to initial run
+		for (int x = 0; x < qrsize; x++) {
+			if (getModule(qrcode, x, y) == runColor) {
+				runX++;
+				if (runX == 5)
+					result += PENALTY_N1;
+				else if (runX > 5)
+					result++;
+			} else {
+				finderPenaltyAddHistory(runX + padRun, runHistory);
+				padRun = 0;
+				if (!runColor)
+					result += finderPenaltyCountPatterns(runHistory, qrsize) * PENALTY_N3;
+				runColor = getModule(qrcode, x, y);
+				runX = 1;
+			}
+		}
+		result += finderPenaltyTerminateAndCount(runColor, runX + padRun, runHistory, qrsize) * PENALTY_N3;
+	}
+	// Adjacent modules in column having same color, and finder-like patterns
+	for (int x = 0; x < qrsize; x++) {
+		bool runColor = false;
+		int runY = 0;
+		int runHistory[7] = {0};
+		int padRun = qrsize;  // Add white border to initial run
+		for (int y = 0; y < qrsize; y++) {
+			if (getModule(qrcode, x, y) == runColor) {
+				runY++;
+				if (runY == 5)
+					result += PENALTY_N1;
+				else if (runY > 5)
+					result++;
+			} else {
+				finderPenaltyAddHistory(runY + padRun, runHistory);
+				padRun = 0;
+				if (!runColor)
+					result += finderPenaltyCountPatterns(runHistory, qrsize) * PENALTY_N3;
+				runColor = getModule(qrcode, x, y);
+				runY = 1;
+			}
+		}
+		result += finderPenaltyTerminateAndCount(runColor, runY + padRun, runHistory, qrsize) * PENALTY_N3;
+	}
+
+	// 2*2 blocks of modules having same color
+	for (int y = 0; y < qrsize - 1; y++) {
+		for (int x = 0; x < qrsize - 1; x++) {
+			bool  color = getModule(qrcode, x, y);
+			if (  color == getModule(qrcode, x + 1, y) &&
+			      color == getModule(qrcode, x, y + 1) &&
+			      color == getModule(qrcode, x + 1, y + 1))
+				result += PENALTY_N2;
+		}
+	}
+
+	// Balance of black and white modules
+	int black = 0;
+	for (int y = 0; y < qrsize; y++) {
+		for (int x = 0; x < qrsize; x++) {
+			if (getModule(qrcode, x, y))
+				black++;
+		}
+	}
+	int total = qrsize * qrsize;  // Note that size is odd, so black/total != 1/2
+	// Compute the smallest integer k >= 0 such that (45-5k)% <= black/total <= (55+5k)%
+	int k = (int)((labs(black * 20L - total * 10L) + total - 1) / total) - 1;
+	result += k * PENALTY_N4;
+	return result;
+}
+
+
+// Can only be called immediately after a white run is added, and
+// returns either 0, 1, or 2. A helper function for getPenaltyScore().
+static int finderPenaltyCountPatterns(const int runHistory[7], int qrsize) {
+	int n = runHistory[1];
+	assert(n <= qrsize * 3);
+	bool core = n > 0 && runHistory[2] == n && runHistory[3] == n * 3 && runHistory[4] == n && runHistory[5] == n;
+	// The maximum QR Code size is 177, hence the black run length n <= 177.
+	// Arithmetic is promoted to int, so n*4 will not overflow.
+	return (core && runHistory[0] >= n * 4 && runHistory[6] >= n ? 1 : 0)
+	     + (core && runHistory[6] >= n * 4 && runHistory[0] >= n ? 1 : 0);
+}
+
+
+// Must be called at the end of a line (row or column) of modules. A helper function for getPenaltyScore().
+static int finderPenaltyTerminateAndCount(bool currentRunColor, int currentRunLength, int runHistory[7], int qrsize) {
+	if (currentRunColor) {  // Terminate black run
+		finderPenaltyAddHistory(currentRunLength, runHistory);
+		currentRunLength = 0;
+	}
+	currentRunLength += qrsize;  // Add white border to final run
+	finderPenaltyAddHistory(currentRunLength, runHistory);
+	return finderPenaltyCountPatterns(runHistory, qrsize);
+}
+
+
+// Pushes the given value to the front and drops the last value. A helper function for getPenaltyScore().
+static void finderPenaltyAddHistory(int currentRunLength, int runHistory[7]) {
+	memmove(&runHistory[1], &runHistory[0], 6 * sizeof(runHistory[0]));
+	runHistory[0] = currentRunLength;
+}
+
+
+
+/*---- Basic QR Code information ----*/
+
+// Public function - see documentation comment in header file.
+int qrcodegen_getSize(const uint8_t qrcode[]) {
+	assert(qrcode != NULL);
+	int result = qrcode[0];
+	assert((qrcodegen_VERSION_MIN * 4 + 17) <= result
+		&& result <= (qrcodegen_VERSION_MAX * 4 + 17));
+	return result;
+}
+
+
+// Public function - see documentation comment in header file.
+bool qrcodegen_getModule(const uint8_t qrcode[], int x, int y) {
+	assert(qrcode != NULL);
+	int qrsize = qrcode[0];
+	return (0 <= x && x < qrsize && 0 <= y && y < qrsize) && getModule(qrcode, x, y);
+}
+
+
+// Gets the module at the given coordinates, which must be in bounds.
+testable bool getModule(const uint8_t qrcode[], int x, int y) {
+	int qrsize = qrcode[0];
+	assert(21 <= qrsize && qrsize <= 177 && 0 <= x && x < qrsize && 0 <= y && y < qrsize);
+	int index = y * qrsize + x;
+	return getBit(qrcode[(index >> 3) + 1], index & 7);
+}
+
+
+// Sets the module at the given coordinates, which must be in bounds.
+testable void setModule(uint8_t qrcode[], int x, int y, bool isBlack) {
+	int qrsize = qrcode[0];
+	assert(21 <= qrsize && qrsize <= 177 && 0 <= x && x < qrsize && 0 <= y && y < qrsize);
+	int index = y * qrsize + x;
+	int bitIndex = index & 7;
+	int byteIndex = (index >> 3) + 1;
+	if (isBlack)
+		qrcode[byteIndex] |= 1 << bitIndex;
+	else
+		qrcode[byteIndex] &= (1 << bitIndex) ^ 0xFF;
+}
+
+
+// Sets the module at the given coordinates, doing nothing if out of bounds.
+testable void setModuleBounded(uint8_t qrcode[], int x, int y, bool isBlack) {
+	int qrsize = qrcode[0];
+	if (0 <= x && x < qrsize && 0 <= y && y < qrsize)
+		setModule(qrcode, x, y, isBlack);
+}
+
+
+// Returns true iff the i'th bit of x is set to 1. Requires x >= 0 and 0 <= i <= 14.
+static bool getBit(int x, int i) {
+	return ((x >> i) & 1) != 0;
+}
+
+
+
+/*---- Segment handling ----*/
+
+// Public function - see documentation comment in header file.
+bool qrcodegen_isAlphanumeric(const char *text) {
+	assert(text != NULL);
+	for (; *text != '\0'; text++) {
+		if (strchr(ALPHANUMERIC_CHARSET, *text) == NULL)
+			return false;
+	}
+	return true;
+}
+
+
+// Public function - see documentation comment in header file.
+bool qrcodegen_isNumeric(const char *text) {
+	assert(text != NULL);
+	for (; *text != '\0'; text++) {
+		if (*text < '0' || *text > '9')
+			return false;
+	}
+	return true;
+}
+
+
+// Public function - see documentation comment in header file.
+size_t qrcodegen_calcSegmentBufferSize(enum qrcodegen_Mode mode, size_t numChars) {
+	int temp = calcSegmentBitLength(mode, numChars);
+	if (temp == -1)
+		return SIZE_MAX;
+	assert(0 <= temp && temp <= INT16_MAX);
+	return ((size_t)temp + 7) / 8;
+}
+
+
+// Returns the number of data bits needed to represent a segment
+// containing the given number of characters using the given mode. Notes:
+// - Returns -1 on failure, i.e. numChars > INT16_MAX or
+//   the number of needed bits exceeds INT16_MAX (i.e. 32767).
+// - Otherwise, all valid results are in the range [0, INT16_MAX].
+// - For byte mode, numChars measures the number of bytes, not Unicode code points.
+// - For ECI mode, numChars must be 0, and the worst-case number of bits is returned.
+//   An actual ECI segment can have shorter data. For non-ECI modes, the result is exact.
+testable int calcSegmentBitLength(enum qrcodegen_Mode mode, size_t numChars) {
+	// All calculations are designed to avoid overflow on all platforms
+	if (numChars > (unsigned int)INT16_MAX)
+		return -1;
+	long result = (long)numChars;
+	if (mode == qrcodegen_Mode_NUMERIC)
+		result = (result * 10 + 2) / 3;  // ceil(10/3 * n)
+	else if (mode == qrcodegen_Mode_ALPHANUMERIC)
+		result = (result * 11 + 1) / 2;  // ceil(11/2 * n)
+	else if (mode == qrcodegen_Mode_BYTE)
+		result *= 8;
+	else if (mode == qrcodegen_Mode_KANJI)
+		result *= 13;
+	else if (mode == qrcodegen_Mode_ECI && numChars == 0)
+		result = 3 * 8;
+	else {  // Invalid argument
+		assert(false);
+		return -1;
+	}
+	assert(result >= 0);
+	if (result > INT16_MAX)
+		return -1;
+	return (int)result;
+}
+
+
+// Public function - see documentation comment in header file.
+struct qrcodegen_Segment qrcodegen_makeBytes(const uint8_t data[], size_t len, uint8_t buf[]) {
+	assert(data != NULL || len == 0);
+	struct qrcodegen_Segment result;
+	result.mode = qrcodegen_Mode_BYTE;
+	result.bitLength = calcSegmentBitLength(result.mode, len);
+	assert(result.bitLength != -1);
+	result.numChars = (int)len;
+	if (len > 0)
+		memcpy(buf, data, len * sizeof(buf[0]));
+	result.data = buf;
+	return result;
+}
+
+
+// Public function - see documentation comment in header file.
+struct qrcodegen_Segment qrcodegen_makeNumeric(const char *digits, uint8_t buf[]) {
+	assert(digits != NULL);
+	struct qrcodegen_Segment result;
+	size_t len = strlen(digits);
+	result.mode = qrcodegen_Mode_NUMERIC;
+	int bitLen = calcSegmentBitLength(result.mode, len);
+	assert(bitLen != -1);
+	result.numChars = (int)len;
+	if (bitLen > 0)
+		memset(buf, 0, ((size_t)bitLen + 7) / 8 * sizeof(buf[0]));
+	result.bitLength = 0;
+
+	unsigned int accumData = 0;
+	int accumCount = 0;
+	for (; *digits != '\0'; digits++) {
+		char c = *digits;
+		assert('0' <= c && c <= '9');
+		accumData = accumData * 10 + (unsigned int)(c - '0');
+		accumCount++;
+		if (accumCount == 3) {
+			appendBitsToBuffer(accumData, 10, buf, &result.bitLength);
+			accumData = 0;
+			accumCount = 0;
+		}
+	}
+	if (accumCount > 0)  // 1 or 2 digits remaining
+		appendBitsToBuffer(accumData, accumCount * 3 + 1, buf, &result.bitLength);
+	assert(result.bitLength == bitLen);
+	result.data = buf;
+	return result;
+}
+
+
+// Public function - see documentation comment in header file.
+struct qrcodegen_Segment qrcodegen_makeAlphanumeric(const char *text, uint8_t buf[]) {
+	assert(text != NULL);
+	struct qrcodegen_Segment result;
+	size_t len = strlen(text);
+	result.mode = qrcodegen_Mode_ALPHANUMERIC;
+	int bitLen = calcSegmentBitLength(result.mode, len);
+	assert(bitLen != -1);
+	result.numChars = (int)len;
+	if (bitLen > 0)
+		memset(buf, 0, ((size_t)bitLen + 7) / 8 * sizeof(buf[0]));
+	result.bitLength = 0;
+
+	unsigned int accumData = 0;
+	int accumCount = 0;
+	for (; *text != '\0'; text++) {
+		const char *temp = strchr(ALPHANUMERIC_CHARSET, *text);
+		assert(temp != NULL);
+		accumData = accumData * 45 + (unsigned int)(temp - ALPHANUMERIC_CHARSET);
+		accumCount++;
+		if (accumCount == 2) {
+			appendBitsToBuffer(accumData, 11, buf, &result.bitLength);
+			accumData = 0;
+			accumCount = 0;
+		}
+	}
+	if (accumCount > 0)  // 1 character remaining
+		appendBitsToBuffer(accumData, 6, buf, &result.bitLength);
+	assert(result.bitLength == bitLen);
+	result.data = buf;
+	return result;
+}
+
+
+// Public function - see documentation comment in header file.
+struct qrcodegen_Segment qrcodegen_makeEci(long assignVal, uint8_t buf[]) {
+	struct qrcodegen_Segment result;
+	result.mode = qrcodegen_Mode_ECI;
+	result.numChars = 0;
+	result.bitLength = 0;
+	if (assignVal < 0)
+		assert(false);
+	else if (assignVal < (1 << 7)) {
+		memset(buf, 0, 1 * sizeof(buf[0]));
+		appendBitsToBuffer((unsigned int)assignVal, 8, buf, &result.bitLength);
+	} else if (assignVal < (1 << 14)) {
+		memset(buf, 0, 2 * sizeof(buf[0]));
+		appendBitsToBuffer(2, 2, buf, &result.bitLength);
+		appendBitsToBuffer((unsigned int)assignVal, 14, buf, &result.bitLength);
+	} else if (assignVal < 1000000L) {
+		memset(buf, 0, 3 * sizeof(buf[0]));
+		appendBitsToBuffer(6, 3, buf, &result.bitLength);
+		appendBitsToBuffer((unsigned int)(assignVal >> 10), 11, buf, &result.bitLength);
+		appendBitsToBuffer((unsigned int)(assignVal & 0x3FF), 10, buf, &result.bitLength);
+	} else
+		assert(false);
+	result.data = buf;
+	return result;
+}
+
+
+// Calculates the number of bits needed to encode the given segments at the given version.
+// Returns a non-negative number if successful. Otherwise returns -1 if a segment has too
+// many characters to fit its length field, or the total bits exceeds INT16_MAX.
+testable int getTotalBits(const struct qrcodegen_Segment segs[], size_t len, int version) {
+	assert(segs != NULL || len == 0);
+	long result = 0;
+	for (size_t i = 0; i < len; i++) {
+		int numChars  = segs[i].numChars;
+		int bitLength = segs[i].bitLength;
+		assert(0 <= numChars  && numChars  <= INT16_MAX);
+		assert(0 <= bitLength && bitLength <= INT16_MAX);
+		int ccbits = numCharCountBits(segs[i].mode, version);
+		assert(0 <= ccbits && ccbits <= 16);
+		if (numChars >= (1L << ccbits))
+			return -1;  // The segment's length doesn't fit the field's bit width
+		result += 4L + ccbits + bitLength;
+		if (result > INT16_MAX)
+			return -1;  // The sum might overflow an int type
+	}
+	assert(0 <= result && result <= INT16_MAX);
+	return (int)result;
+}
+
+
+// Returns the bit width of the character count field for a segment in the given mode
+// in a QR Code at the given version number. The result is in the range [0, 16].
+static int numCharCountBits(enum qrcodegen_Mode mode, int version) {
+	assert(qrcodegen_VERSION_MIN <= version && version <= qrcodegen_VERSION_MAX);
+	int i = (version + 7) / 17;
+	switch (mode) {
+		case qrcodegen_Mode_NUMERIC     : { static const int temp[] = {10, 12, 14}; return temp[i]; }
+		case qrcodegen_Mode_ALPHANUMERIC: { static const int temp[] = { 9, 11, 13}; return temp[i]; }
+		case qrcodegen_Mode_BYTE        : { static const int temp[] = { 8, 16, 16}; return temp[i]; }
+		case qrcodegen_Mode_KANJI       : { static const int temp[] = { 8, 10, 12}; return temp[i]; }
+		case qrcodegen_Mode_ECI         : return 0;
+		default:  assert(false);  return -1;  // Dummy value
+	}
+}

examples/common_components/qrcode/qrcodegen.h

@@ -0,0 +1,311 @@
+/*
+ * QR Code generator library (C)
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/*
+ * This library creates QR Code symbols, which is a type of two-dimension barcode.
+ * Invented by Denso Wave and described in the ISO/IEC 18004 standard.
+ * A QR Code structure is an immutable square grid of black and white cells.
+ * The library provides functions to create a QR Code from text or binary data.
+ * The library covers the QR Code Model 2 specification, supporting all versions (sizes)
+ * from 1 to 40, all 4 error correction levels, and 4 character encoding modes.
+ *
+ * Ways to create a QR Code object:
+ * - High level: Take the payload data and call qrcodegen_encodeText() or qrcodegen_encodeBinary().
+ * - Low level: Custom-make the list of segments and call
+ *   qrcodegen_encodeSegments() or qrcodegen_encodeSegmentsAdvanced().
+ * (Note that all ways require supplying the desired error correction level and various byte buffers.)
+ */
+
+
+/*---- Enum and struct types----*/
+
+/*
+ * The error correction level in a QR Code symbol.
+ */
+enum qrcodegen_Ecc {
+	// Must be declared in ascending order of error protection
+	// so that an internal qrcodegen function works properly
+	qrcodegen_Ecc_LOW = 0 ,  // The QR Code can tolerate about  7% erroneous codewords
+	qrcodegen_Ecc_MEDIUM  ,  // The QR Code can tolerate about 15% erroneous codewords
+	qrcodegen_Ecc_QUARTILE,  // The QR Code can tolerate about 25% erroneous codewords
+	qrcodegen_Ecc_HIGH    ,  // The QR Code can tolerate about 30% erroneous codewords
+};
+
+
+/*
+ * The mask pattern used in a QR Code symbol.
+ */
+enum qrcodegen_Mask {
+	// A special value to tell the QR Code encoder to
+	// automatically select an appropriate mask pattern
+	qrcodegen_Mask_AUTO = -1,
+	// The eight actual mask patterns
+	qrcodegen_Mask_0 = 0,
+	qrcodegen_Mask_1,
+	qrcodegen_Mask_2,
+	qrcodegen_Mask_3,
+	qrcodegen_Mask_4,
+	qrcodegen_Mask_5,
+	qrcodegen_Mask_6,
+	qrcodegen_Mask_7,
+};
+
+
+/*
+ * Describes how a segment's data bits are interpreted.
+ */
+enum qrcodegen_Mode {
+	qrcodegen_Mode_NUMERIC      = 0x1,
+	qrcodegen_Mode_ALPHANUMERIC = 0x2,
+	qrcodegen_Mode_BYTE         = 0x4,
+	qrcodegen_Mode_KANJI        = 0x8,
+	qrcodegen_Mode_ECI          = 0x7,
+};
+
+
+/*
+ * A segment of character/binary/control data in a QR Code symbol.
+ * The mid-level way to create a segment is to take the payload data
+ * and call a factory function such as qrcodegen_makeNumeric().
+ * The low-level way to create a segment is to custom-make the bit buffer
+ * and initialize a qrcodegen_Segment struct with appropriate values.
+ * 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.
+ * Moreover, the maximum allowed bit length is 32767 because
+ * the largest QR Code (version 40) has 31329 modules.
+ */
+struct qrcodegen_Segment {
+	// The mode indicator of this segment.
+	enum qrcodegen_Mode mode;
+
+	// The length of this segment's unencoded data. Measured in characters for
+	// numeric/alphanumeric/kanji mode, bytes for byte mode, and 0 for ECI mode.
+	// Always zero or positive. Not the same as the data's bit length.
+	int numChars;
+
+	// The data bits of this segment, packed in bitwise big endian.
+	// Can be null if the bit length is zero.
+	uint8_t *data;
+
+	// The number of valid data bits used in the buffer. Requires
+	// 0 <= bitLength <= 32767, and bitLength <= (capacity of data array) * 8.
+	// The character count (numChars) must agree with the mode and the bit buffer length.
+	int bitLength;
+};
+
+
+
+/*---- Macro constants and functions ----*/
+
+#define qrcodegen_VERSION_MIN   1  // The minimum version number supported in the QR Code Model 2 standard
+#define qrcodegen_VERSION_MAX  40  // The maximum version number supported in the QR Code Model 2 standard
+
+// Calculates the number of bytes needed to store any QR Code up to and including the given version number,
+// as a compile-time constant. For example, 'uint8_t buffer[qrcodegen_BUFFER_LEN_FOR_VERSION(25)];'
+// can store any single QR Code from version 1 to 25 (inclusive). The result fits in an int (or int16).
+// Requires qrcodegen_VERSION_MIN <= n <= qrcodegen_VERSION_MAX.
+#define qrcodegen_BUFFER_LEN_FOR_VERSION(n)  ((((n) * 4 + 17) * ((n) * 4 + 17) + 7) / 8 + 1)
+
+// The worst-case number of bytes needed to store one QR Code, up to and including
+// version 40. This value equals 3918, which is just under 4 kilobytes.
+// Use this more convenient value to avoid calculating tighter memory bounds for buffers.
+#define qrcodegen_BUFFER_LEN_MAX  qrcodegen_BUFFER_LEN_FOR_VERSION(qrcodegen_VERSION_MAX)
+
+
+
+/*---- Functions (high level) to generate QR Codes ----*/
+
+/*
+ * Encodes the given text string to a QR Code, returning true if encoding succeeded.
+ * If the data is too long to fit in any version in the given range
+ * at the given ECC level, then false is returned.
+ * - The input text must be encoded in UTF-8 and contain no NULs.
+ * - The variables ecl and mask must correspond to enum constant values.
+ * - Requires 1 <= minVersion <= maxVersion <= 40.
+ * - The arrays tempBuffer and qrcode must each have a length
+ *   of at least qrcodegen_BUFFER_LEN_FOR_VERSION(maxVersion).
+ * - After the function returns, tempBuffer contains no useful data.
+ * - If successful, the resulting QR Code may use numeric,
+ *   alphanumeric, or byte mode to encode the text.
+ * - In the most optimistic case, a QR Code at version 40 with low ECC
+ *   can hold any UTF-8 string up to 2953 bytes, or any alphanumeric string
+ *   up to 4296 characters, or any digit string up to 7089 characters.
+ *   These numbers represent the hard upper limit of the QR Code standard.
+ * - Please consult the QR Code specification for information on
+ *   data capacities per version, ECC level, and text encoding mode.
+ */
+bool qrcodegen_encodeText(const char *text, uint8_t tempBuffer[], uint8_t qrcode[],
+	enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl);
+
+
+/*
+ * Encodes the given binary data to a QR Code, returning true if encoding succeeded.
+ * If the data is too long to fit in any version in the given range
+ * at the given ECC level, then false is returned.
+ * - The input array range dataAndTemp[0 : dataLen] should normally be
+ *   valid UTF-8 text, but is not required by the QR Code standard.
+ * - The variables ecl and mask must correspond to enum constant values.
+ * - Requires 1 <= minVersion <= maxVersion <= 40.
+ * - The arrays dataAndTemp and qrcode must each have a length
+ *   of at least qrcodegen_BUFFER_LEN_FOR_VERSION(maxVersion).
+ * - After the function returns, the contents of dataAndTemp may have changed,
+ *   and does not represent useful data anymore.
+ * - If successful, the resulting QR Code will use byte mode to encode the data.
+ * - In the most optimistic case, a QR Code at version 40 with low ECC can hold any byte
+ *   sequence up to length 2953. This is the hard upper limit of the QR Code standard.
+ * - Please consult the QR Code specification for information on
+ *   data capacities per version, ECC level, and text encoding mode.
+ */
+bool qrcodegen_encodeBinary(uint8_t dataAndTemp[], size_t dataLen, uint8_t qrcode[],
+	enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl);
+
+
+/*---- Functions (low level) to generate QR Codes ----*/
+
+/*
+ * Renders a QR Code representing the given segments at the given error correction level.
+ * The smallest possible QR Code version is automatically chosen for the output. Returns true if
+ * QR Code creation succeeded, or false if the data is too long to fit in any version. The ECC level
+ * of the result may be higher than the ecl argument if it can be done without increasing the version.
+ * This function allows the user to create a custom sequence of segments that switches
+ * between modes (such as alphanumeric and byte) to encode text in less space.
+ * This is a low-level API; the high-level API is qrcodegen_encodeText() and qrcodegen_encodeBinary().
+ * To save memory, the segments' data buffers can alias/overlap tempBuffer, and will
+ * result in them being clobbered, but the QR Code output will still be correct.
+ * But the qrcode array must not overlap tempBuffer or any segment's data buffer.
+ */
+bool qrcodegen_encodeSegments(const struct qrcodegen_Segment segs[], size_t len,
+	enum qrcodegen_Ecc ecl, uint8_t tempBuffer[], uint8_t qrcode[]);
+
+
+/*
+ * Renders a QR Code representing the given segments with the given encoding parameters.
+ * Returns true if QR Code creation succeeded, or false if the data is too long to fit in the range of versions.
+ * The smallest possible QR Code version within the given range is automatically
+ * chosen for the output. Iff boostEcl is true, then the ECC level of the result
+ * may be higher than the ecl argument if it can be done without increasing the
+ * version. The mask is either between qrcodegen_Mask_0 to 7 to force that mask, or
+ * qrcodegen_Mask_AUTO to automatically choose an appropriate mask (which may be slow).
+ * This function allows the user to create a custom sequence of segments that switches
+ * between modes (such as alphanumeric and byte) to encode text in less space.
+ * This is a low-level API; the high-level API is qrcodegen_encodeText() and qrcodegen_encodeBinary().
+ * To save memory, the segments' data buffers can alias/overlap tempBuffer, and will
+ * result in them being clobbered, but the QR Code output will still be correct.
+ * But the qrcode array must not overlap tempBuffer or any segment's data buffer.
+ */
+bool qrcodegen_encodeSegmentsAdvanced(const struct qrcodegen_Segment segs[], size_t len, enum qrcodegen_Ecc ecl,
+	int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl, uint8_t tempBuffer[], uint8_t qrcode[]);
+
+
+/*
+ * Tests whether the given string can be encoded as a segment in alphanumeric mode.
+ * A string is encodable iff each character is in the following set: 0 to 9, A to Z
+ * (uppercase only), space, dollar, percent, asterisk, plus, hyphen, period, slash, colon.
+ */
+bool qrcodegen_isAlphanumeric(const char *text);
+
+
+/*
+ * Tests whether the given string can be encoded as a segment in numeric mode.
+ * A string is encodable iff each character is in the range 0 to 9.
+ */
+bool qrcodegen_isNumeric(const char *text);
+
+
+/*
+ * Returns the number of bytes (uint8_t) needed for the data buffer of a segment
+ * containing the given number of characters using the given mode. Notes:
+ * - Returns SIZE_MAX on failure, i.e. numChars > INT16_MAX or
+ *   the number of needed bits exceeds INT16_MAX (i.e. 32767).
+ * - Otherwise, all valid results are in the range [0, ceil(INT16_MAX / 8)], i.e. at most 4096.
+ * - It is okay for the user to allocate more bytes for the buffer than needed.
+ * - For byte mode, numChars measures the number of bytes, not Unicode code points.
+ * - For ECI mode, numChars must be 0, and the worst-case number of bytes is returned.
+ *   An actual ECI segment can have shorter data. For non-ECI modes, the result is exact.
+ */
+size_t qrcodegen_calcSegmentBufferSize(enum qrcodegen_Mode mode, size_t numChars);
+
+
+/*
+ * Returns a segment representing the given binary data encoded in
+ * byte mode. All input byte arrays are acceptable. Any text string
+ * can be converted to UTF-8 bytes and encoded as a byte mode segment.
+ */
+struct qrcodegen_Segment qrcodegen_makeBytes(const uint8_t data[], size_t len, uint8_t buf[]);
+
+
+/*
+ * Returns a segment representing the given string of decimal digits encoded in numeric mode.
+ */
+struct qrcodegen_Segment qrcodegen_makeNumeric(const char *digits, uint8_t buf[]);
+
+
+/*
+ * 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.
+ */
+struct qrcodegen_Segment qrcodegen_makeAlphanumeric(const char *text, uint8_t buf[]);
+
+
+/*
+ * Returns a segment representing an Extended Channel Interpretation
+ * (ECI) designator with the given assignment value.
+ */
+struct qrcodegen_Segment qrcodegen_makeEci(long assignVal, uint8_t buf[]);
+
+
+/*---- Functions to extract raw data from QR Codes ----*/
+
+/*
+ * Returns the side length of the given QR Code, assuming that encoding succeeded.
+ * The result is in the range [21, 177]. Note that the length of the array buffer
+ * is related to the side length - every 'uint8_t qrcode[]' must have length at least
+ * qrcodegen_BUFFER_LEN_FOR_VERSION(version), which equals ceil(size^2 / 8 + 1).
+ */
+int qrcodegen_getSize(const uint8_t qrcode[]);
+
+
+/*
+ * Returns the color of the module (pixel) at the given coordinates, which is 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.
+ */
+bool qrcodegen_getModule(const uint8_t qrcode[], int x, int y);
+
+
+#ifdef __cplusplus
+}
+#endif