File content as of revision 76:84e6c4994e29:

#include "RomCommands.h"

using namespace OneWire;

enum OwRomCmd
{
    ReadRomCmd = 0x33,
    MatchRomCmd = 0x55,
    SearchRomCmd = 0xF0,
    SkipRomCmd = 0xCC,
    ResumeCmd = 0xA5,
    OverdriveSkipRomCmd = 0x3C,
    OverdriveMatchRomCmd = 0x69
};

OneWireMaster::CmdResult RomCommands::OWFirst(OneWireMaster & owMaster, SearchState & searchState)
{
    // Reset and begin a new search
    searchState.reset();
    return OWSearch(owMaster, searchState);
}

OneWireMaster::CmdResult RomCommands::OWNext(OneWireMaster & owMaster, SearchState & searchState)
{
    // Continue the previous search
    return OWSearch(owMaster, searchState);
}

OneWireMaster::CmdResult RomCommands::OWVerify(OneWireMaster & owMaster, const RomId & romId)
{
    OneWireMaster::CmdResult result;
    SearchState searchState;

    searchState.romId = romId;

    // set search to find the same device
    searchState.last_discrepancy = 64;
    searchState.last_device_flag = false;

    result = OWSearch(owMaster, searchState);
    if (result == OneWireMaster::Success)
    {
        // check if same device found
        if (romId != searchState.romId)
        {
            result = OneWireMaster::OperationFailure;
        }
    }

    return result;
}

void RomCommands::OWTargetSetup(SearchState & searchState)
{
    // set the search state to find SearchFamily type devices
    uint8_t familyCode = searchState.romId.familyCode();
    searchState.reset();
    searchState.romId.setFamilyCode(familyCode);
    searchState.last_discrepancy = 64;
}

void RomCommands::OWFamilySkipSetup(SearchState & searchState)
{
    // set the Last discrepancy to last family discrepancy
    searchState.last_discrepancy = searchState.last_family_discrepancy;

    // clear the last family discrpepancy
    searchState.last_family_discrepancy = 0;

    // check for end of list
    if (searchState.last_discrepancy == 0)
    {
        searchState.last_device_flag = true;
    }
}

OneWireMaster::CmdResult RomCommands::OWReadRom(OneWireMaster & owMaster, RomId & romId)
{
    OneWireMaster::CmdResult result;
    RomId readId;

    result = owMaster.OWReset();
    if (result == OneWireMaster::Success)
    {
        result = owMaster.OWWriteByte(ReadRomCmd);
    }

    // read the ROM
    if (result == OneWireMaster::Success)
    {
        result = owMaster.OWReadBlock(readId, RomId::byteLen);
    }

    // verify CRC8
    if (result == OneWireMaster::Success)
    {
        if (readId.crc8Valid())
        {
            romId = readId;
        }
        else
        {
            result = OneWireMaster::OperationFailure;
        }
    }

    return result;
}
  
OneWireMaster::CmdResult RomCommands::OWSkipRom(OneWireMaster & owMaster)
{
    OneWireMaster::CmdResult result;

    result = owMaster.OWReset();
    if (result == OneWireMaster::Success)
    {
        result = owMaster.OWWriteByte(SkipRomCmd);
    }

    return result;
}
  
OneWireMaster::CmdResult RomCommands::OWMatchRom(OneWireMaster & owMaster, const RomId & romId)
{
    OneWireMaster::CmdResult result;

    uint8_t buf[1 + RomId::byteLen];

    // use MatchROM
    result = owMaster.OWReset();
    if (result == OneWireMaster::Success)
    {
        buf[0] = MatchRomCmd;
        std::memcpy(&buf[1], romId, RomId::byteLen);
        // send command and rom
        result = owMaster.OWWriteBlock(buf, 1 + RomId::byteLen);
    }

    return result;
}
  
OneWireMaster::CmdResult RomCommands::OWOverdriveSkipRom(OneWireMaster & owMaster)
{
    OneWireMaster::CmdResult result = owMaster.OWSetSpeed(OneWireMaster::StandardSpeed);

    if (result == OneWireMaster::Success)
    {
        result = owMaster.OWReset();
    }

    if (result == OneWireMaster::Success)
    {
        result = owMaster.OWWriteByte(OverdriveSkipRomCmd);
    }

    if (result == OneWireMaster::Success)
    {
        result = owMaster.OWSetSpeed(OneWireMaster::OverdriveSpeed);
    }

    return result;
}
  
OneWireMaster::CmdResult RomCommands::OWOverdriveMatchRom(OneWireMaster & owMaster, const RomId & romId)
{
    OneWireMaster::CmdResult result;

    // use overdrive MatchROM
    owMaster.OWSetSpeed(OneWireMaster::StandardSpeed);

    result = owMaster.OWReset();
    if (result == OneWireMaster::Success)
    {
        result = owMaster.OWWriteByte(OverdriveMatchRomCmd);
        if (result == OneWireMaster::Success)
        {
            owMaster.OWSetSpeed(OneWireMaster::OverdriveSpeed);
            // send ROM
            result = owMaster.OWWriteBlock(romId, RomId::byteLen);
        }
    }
    return result;
}
   
OneWireMaster::CmdResult RomCommands::OWResume(OneWireMaster & owMaster)
{
    OneWireMaster::CmdResult result;

    result = owMaster.OWReset();
    if (result == OneWireMaster::Success)
    {
        result = owMaster.OWWriteByte(ResumeCmd);
    }

    return result;
}

OneWireMaster::CmdResult RomCommands::OWSearch(OneWireMaster & owMaster, SearchState & searchState)
{
    uint8_t id_bit_number;
    uint8_t last_zero, rom_byte_number;
    uint8_t id_bit, cmp_id_bit;
    uint8_t rom_byte_mask;
    bool search_result;
    uint8_t crc8 = 0;
    OneWireMaster::SearchDirection search_direction;

    // initialize for search
    id_bit_number = 1;
    last_zero = 0;
    rom_byte_number = 0;
    rom_byte_mask = 1;
    search_result = false;

    // if the last call was not the last one
    if (!searchState.last_device_flag)
    {
        // 1-Wire reset
        OneWireMaster::CmdResult result = owMaster.OWReset();
        if (result != OneWireMaster::Success)
        {
            // reset the search
            searchState.reset();
            return result;
        }

        // issue the search command 
        owMaster.OWWriteByte(SearchRomCmd);

        // loop to do the search
        do
        {
            // if this discrepancy if before the Last Discrepancy
            // on a previous next then pick the same as last time
            if (id_bit_number < searchState.last_discrepancy)
            {
                if ((searchState.romId[rom_byte_number] & rom_byte_mask) > 0)
                {
                    search_direction = OneWireMaster::WriteOne;
                }
                else
                {
                    search_direction = OneWireMaster::WriteZero;
                }
            }
            else
            {
                // if equal to last pick 1, if not then pick 0
                if (id_bit_number == searchState.last_discrepancy)
                {
                    search_direction = OneWireMaster::WriteOne;
                }
                else
                {
                    search_direction = OneWireMaster::WriteZero;
                }
            }

            // Peform a triple operation on the DS2465 which will perform 2 read bits and 1 write bit
            result = owMaster.OWTriplet(search_direction, id_bit, cmp_id_bit);
            if (result != OneWireMaster::Success)
            {
                return result;
            }

            // check for no devices on 1-wire
            if (id_bit && cmp_id_bit)
            {
                break;
            }
            else
            {
                if (!id_bit && !cmp_id_bit && (search_direction == OneWireMaster::WriteZero))
                {
                    last_zero = id_bit_number;

                    // check for Last discrepancy in family
                    if (last_zero < 9)
                    {
                        searchState.last_family_discrepancy = last_zero;
                    }
                }

                // set or clear the bit in the ROM byte rom_byte_number
                // with mask rom_byte_mask
                if (search_direction == OneWireMaster::WriteOne)
                {
                    searchState.romId[rom_byte_number] |= rom_byte_mask;
                }
                else
                {
                    searchState.romId[rom_byte_number] &= (uint8_t)~rom_byte_mask;
                }

                // increment the byte counter id_bit_number
                // and shift the mask rom_byte_mask
                id_bit_number++;
                rom_byte_mask <<= 1;

                // if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
                if (rom_byte_mask == 0)
                {
                    crc8 = RomId::calculateCrc8(crc8, searchState.romId[rom_byte_number]);  // accumulate the CRC
                    rom_byte_number++;
                    rom_byte_mask = 1;
                }
            }
        } while (rom_byte_number < RomId::byteLen);  // loop until through all ROM bytes 0-7

        // if the search was successful then
        if (!((id_bit_number <= (RomId::byteLen * 8)) || (crc8 != 0)))
        {
            // search successful so set m_last_discrepancy,m_last_device_flag,search_result
            searchState.last_discrepancy = last_zero;

            // check for last device
            if (searchState.last_discrepancy == 0)
            {
                searchState.last_device_flag = true;
            }

            search_result = true;
        }
    }

    // if no device found then reset counters so next 'search' will be like a first
    if (!search_result || (searchState.romId.familyCode() == 0))
    {
        searchState.reset();
        search_result = false;
    }

    return (search_result ? OneWireMaster::Success : OneWireMaster::OperationFailure);
}