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