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QR-Code-generator
mirror of https://github.com/nayuki/QR-Code-generator
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Continued implementing C library by adding main QR Code encoding function for text, including support for alphanumeric and numeric mode segments.

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pull/11/head
Project Nayuki 8 years ago
parent 53359d7ef2
commit 47fc47938a
2 changed files with 147 additions and 0 deletions
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137
c/qrcodegen.c
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@ -57,6 +57,8 @@ static uint8_t finiteFieldMultiply(uint8_t x, uint8_t y);
/*---- Private tables of constants ----*/
static const char *ALPHANUMERIC_CHARSET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:";
static const int16_t NUM_ERROR_CORRECTION_CODEWORDS[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
@ -84,6 +86,141 @@ static const int PENALTY_N4 = 10;
/*---- Function implementations ----*/
// Public function - see documentation comment in header file.
int qrcodegen_encodeText(const char *text, uint8_t tempBuffer[], uint8_t qrcode[],
enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask) {
assert(1 <= minVersion && minVersion <= maxVersion && maxVersion <= 40);
assert(0 <= (int)ecl && (int)ecl <= 3 && -1 <= (int)mask && (int)mask <= 7);
// Get text properties
int textLen = 0;
bool isNumeric = true;
bool isAlphanumeric = true;
for (const char *p = text; *p != '\0'; p++, textLen++) {
if (textLen == INT16_MAX) // Note: INT16_MAX < INT_MAX && INT16_MAX < SIZE_MAX
return 0;
char c = *p;
if (c < '0' || c > '9') {
isNumeric = false;
isAlphanumeric &= strchr(ALPHANUMERIC_CHARSET, c) != NULL;
}
}
int textBits;
if (isNumeric) { // textBits = textLen * 3 + ceil(textLen / 3)
if (textLen > INT_MAX / 3)
return 0;
textBits = textLen * 3;
if (textLen > INT_MAX - 2 || textLen > INT_MAX - textBits)
return 0;
textBits += (textLen + 2) / 3;
} else if (isAlphanumeric) { // textBits = textLen * 5 + ceil(textLen / 2)
if (textLen > INT_MAX / 5)
return 0;
textBits = textLen * 5;
if (textLen > INT_MAX - 1 || textLen > INT_MAX - textBits)
return 0;
textBits += (textLen + 1) / 2;
} else { // Use binary mode
if (textLen > qrcodegen_BUFFER_LEN_FOR_VERSION(maxVersion))
return 0;
for (int i = 0; i < textLen; i++)
tempBuffer[i] = (uint8_t)text[i];
return qrcodegen_encodeBinary(tempBuffer, (size_t)textLen, qrcode, ecl, minVersion, maxVersion, mask);
}
int version;
int dataUsedBits = -1;
int dataCapacityBits = -1;
int lengthBits = -1;
for (version = minVersion; ; version++) {
if (version <= 9)
lengthBits = isNumeric ? 10 : 9;
else if (version <= 26)
lengthBits = isNumeric ? 12 : 11;
else
lengthBits = isNumeric ? 14 : 13;
if (textLen < (1 << lengthBits)) {
dataCapacityBits = getNumDataCodewords(version, ecl) * 8; // Number of data bits available
dataUsedBits = 4 + lengthBits;
if (textBits > INT_MAX - dataUsedBits)
continue;
dataUsedBits += textBits;
if (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
return 0;
}
assert(dataUsedBits >= 0 && dataCapacityBits >= 0);
memset(qrcode, 0, qrcodegen_BUFFER_LEN_FOR_VERSION(version) * sizeof(qrcode[0]));
int bitLen = 0;
appendBitsToBuffer(isNumeric ? 1 : 2, 4, qrcode, &bitLen);
appendBitsToBuffer((uint16_t)textLen, lengthBits, qrcode, &bitLen);
if (isNumeric) {
int accumData = 0;
int accumCount = 0;
for (const char *p = text; *p != '\0'; p++) {
accumData = accumData * 10 + (*p - '0');
accumCount++;
if (accumCount == 3) {
appendBitsToBuffer(accumData, 10, qrcode, &bitLen);
accumData = 0;
accumCount = 0;
}
}
if (accumCount > 0) // 1 or 2 digits remaining
appendBitsToBuffer(accumData, accumCount * 3 + 1, qrcode, &bitLen);
} else { // isAlphanumeric
int accumData = 0;
int accumCount = 0;
for (const char *p = text; *p != '\0'; p++) {
accumData = accumData * 45 + (strchr(ALPHANUMERIC_CHARSET, *p) - ALPHANUMERIC_CHARSET);
accumCount++;
if (accumCount == 2) {
appendBitsToBuffer(accumData, 11, qrcode, &bitLen);
accumData = 0;
accumCount = 0;
}
}
if (accumCount > 0) // 1 character remaining
appendBitsToBuffer(accumData, 6, qrcode, &bitLen);
}
int terminatorBits = dataCapacityBits - bitLen;
if (terminatorBits > 4)
terminatorBits = 4;
appendBitsToBuffer(0, terminatorBits, qrcode, &bitLen);
appendBitsToBuffer(0, (8 - bitLen % 8) % 8, qrcode, &bitLen);
for (uint8_t padByte = 0xEC; bitLen < dataCapacityBits; padByte ^= 0xEC ^ 0x11)
appendBitsToBuffer(padByte, 8, qrcode, &bitLen);
assert(bitLen % 8 == 0);
appendErrorCorrection(qrcode, version, ecl, tempBuffer);
initializeFunctionalModules(version, qrcode);
drawCodewords(tempBuffer, getNumRawDataModules(version) / 8, qrcode, version);
drawWhiteFunctionModules(qrcode, version);
initializeFunctionalModules(version, tempBuffer);
if (mask == qrcodegen_Mask_AUTO) { // Automatically choose best mask
long minPenalty = LONG_MAX;
for (int i = 0; i < 8; i++) {
drawFormatBits(ecl, i, qrcode, qrcodegen_getSize(version));
applyMask(tempBuffer, qrcode, qrcodegen_getSize(version), i);
long penalty = getPenaltyScore(qrcode, qrcodegen_getSize(version));
if (penalty < minPenalty) {
mask = (enum qrcodegen_Mask)i;
minPenalty = penalty;
}
applyMask(tempBuffer, qrcode, qrcodegen_getSize(version), i); // Undoes the mask due to XOR
}
}
assert(0 <= (int)mask && (int)mask <= 7);
applyMask(tempBuffer, qrcode, qrcodegen_getSize(version), (int)mask);
drawFormatBits(ecl, (int)mask, qrcode, qrcodegen_getSize(version));
return version;
}
// Public function - see documentation comment in header file.
int qrcodegen_encodeBinary(uint8_t dataAndTemp[], size_t dataLen, uint8_t qrcode[],
enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask) {

10
c/qrcodegen.h
Unescape View File

@ -64,6 +64,16 @@ enum qrcodegen_Mask {
#define qrcodegen_BUFFER_LEN_MAX qrcodegen_BUFFER_LEN_FOR_VERSION(40)
/*
* Encodes the given text data to a QR Code symbol, returning the actual version number used.
* If the data is too long to fit in any version in the given range at the given ECC level,
* then 0 is returned. Both dataAndTemp and qrcode each must have length at least
* qrcodegen_BUFFER_LEN_FOR_VERSION(maxVersion).
*/
int qrcodegen_encodeText(const char *text, uint8_t tempBuffer[], uint8_t qrcode[],
enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask);
/*
* Encodes the given binary data to a QR Code symbol, return the actual version number used.
* If the data is too long to fit in any version in the given range at the given ECC level,

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