Method writeSector

arch/apple2/encoder.cc:73–186

     */

    void writeSector(
        std::vector<bool>& bits, unsigned& cursor, const Sector& sector) const
    {
        if ((sector.status == Sector::OK) or
            (sector.status == Sector::BAD_CHECKSUM))
        {
            auto write_bit = [&](bool val)
            {
                if (cursor <= bits.size())
                {
                    bits[cursor] = val;
                }
                cursor++;
            };

            auto write_bits = [&](uint32_t bits, int width)
            {
                for (int i = width; i--;)
                {
                    write_bit(bits & (1u << i));
                }
            };

            auto write_gcr44 = [&](uint8_t value)
            {
                write_bits((value << 7) | value | 0xaaaa, 16);
            };

            auto write_gcr6 = [&](uint8_t value)
            {
                write_bits(encode_data_gcr(value), 8);
            };

            // The special "FF40" sequence is used to synchronize the receiving
            // shift register. It's written as "1111 1111 00"; FF indicates the
            // 8 consecutive 1-bits, while "40" indicates the total number of
            // microseconds.
            auto write_ff40 = [&](int n = 1)
            {
                for (; n--;)
                {
                    write_bits(0xff << 2, 10);
                }
            };

            // There is data to encode to disk.
            if ((sector.data.size() != APPLE2_SECTOR_LENGTH))
                error("unsupported sector size {} --- you must pick 256",
                    sector.data.size());

            // Write address syncing leader : A sequence of "FF40"s; 5 of them
            // are said to suffice to synchronize the decoder.
            // "FF40" indicates that the actual data written is "1111
            // 1111 00" i.e., 8 1s and a total of 40 microseconds
            //
            // In standard formatting, the first logical sector apparently gets
            // extra padding.
            write_ff40(sector.logicalSector == 0 ? 32 : 8);