#107 QR code error correction capacity optimization bug

[Daniel Gredler]

This is another one I'm not 100% sure is a bug, but looks suspicious. The following block of code in qr.c seems to compare bit length to codeword count:

/* Ensure maxium error correction capacity */
if (est_binlen <= qr_data_codewords_M[version - 1]) {
    ecc_level = LEVEL_M;
}
if (est_binlen <= qr_data_codewords_Q[version - 1]) {
    ecc_level = LEVEL_Q;
}
if (est_binlen <= qr_data_codewords_H[version - 1]) {
    ecc_level = LEVEL_H;
}

Similar code elsewhere in this file multiplies the codeword counts by 8 so that we're comparing bit lengths.

The equivalent Okapi code also multiplies the codeword count by 8:

    /* Ensure maximum error correction capacity */
    if (est_binlen <= (QR_DATA_CODEWORDS_M[version - 1] * 8)) {
        ecc_level = EccMode.M;
    }
    if (est_binlen <= (QR_DATA_CODEWORDS_Q[version - 1] * 8)) {
        ecc_level = EccMode.Q;
    }
    if (est_binlen <= (QR_DATA_CODEWORDS_H[version - 1] * 8)) {
        ecc_level = EccMode.H;

}

[Robin Stuart]

Thanks Daniel,

Well spotted! The Okapi code is correct. I have now corrected Zint.

Robin.