diff --git a/c/qrcodegen.h b/c/qrcodegen.h index 7d925ad..f4c4f9f 100644 --- a/c/qrcodegen.h +++ b/c/qrcodegen.h @@ -27,7 +27,7 @@ #include -/*---- Enumeration types and constants ----*/ +/*---- Enumeration types and values ----*/ /* * Represents the error correction level used in a QR Code symbol. @@ -59,7 +59,7 @@ enum qrcodegen_Mask { /*---- Macro constants and functions ----*/ -// The minimum and maximum defined QR Code version numbers. +// The minimum and maximum defined QR Code version numbers for Model 2. #define qrcodegen_VERSION_MIN 1 #define qrcodegen_VERSION_MAX 40 @@ -69,7 +69,7 @@ enum qrcodegen_Mask { #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 3917, which is just under 4 kilobytes. +// version 40. This value equals 3918, which is just under 4 kilobytes. #define qrcodegen_BUFFER_LEN_MAX qrcodegen_BUFFER_LEN_FOR_VERSION(qrcodegen_VERSION_MAX) @@ -77,22 +77,45 @@ enum qrcodegen_Mask { /*---- Top-level QR Code functions ----*/ /* - * Encodes the given text data to a QR Code symbol, returning whether 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. Both dataAndTemp and qrcode each must have length at least - * qrcodegen_BUFFER_LEN_FOR_VERSION(maxVersion). The text must be encoded in UTF-8. - * The resulting QR Code may use numeric, alphanumeric, or byte mode to encode the text. + * Encodes the given text string to a QR Code symbol, 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 standard document 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 symbol, returning whether 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. dataAndTemp[0 : dataLen] represents the input data, and the function - * may overwrite the array's contents as a temporary work area. Both dataAndTemp and qrcode - * must have length at least qrcodegen_BUFFER_LEN_FOR_VERSION(maxVersion). + * Encodes the given binary data to a QR Code symbol, 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 standard document 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); @@ -102,17 +125,17 @@ bool qrcodegen_encodeBinary(uint8_t dataAndTemp[], size_t dataLen, uint8_t qrcod /*---- Low-level QR Code functions ----*/ /* - * Returns the side length of the given QR Code, assuming that the buffer is valid. + * Returns the side length of the given QR Code, assuming that encoding succeeded. * The result is in the range [21, 177]. Note that every 'uint8_t qrcode[]' buffer - * must have a length of at least ceil(size^2 / 8 + 1), which also equals - * qrcodegen_BUFFER_LEN_FOR_VERSION(version). + * must have a length of 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 either - * true for white or false for black. The top left corner has the coordinates (x=0, y=0). + * 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);