flipperzero-firmware/applications/accessor/helpers/wiegand.cpp

#include "wiegand.h"
#include <furi.h>
#include <furi-hal.h>

volatile unsigned long WIEGAND::_cardTempHigh = 0;
volatile unsigned long WIEGAND::_cardTemp = 0;
volatile unsigned long WIEGAND::_lastWiegand = 0;
unsigned long WIEGAND::_code = 0;
unsigned long WIEGAND::_codeHigh = 0;
volatile int WIEGAND::_bitCount = 0;
int WIEGAND::_wiegandType = 0;

constexpr uint32_t clocks_in_ms = 64 * 1000;

WIEGAND::WIEGAND() {
}

unsigned long WIEGAND::getCode() {
    return _code;
}

unsigned long WIEGAND::getCodeHigh() {
    return _codeHigh;
}

int WIEGAND::getWiegandType() {
    return _wiegandType;
}

bool WIEGAND::available() {
    bool ret;
    __disable_irq();
    ret = DoWiegandConversion();
    __enable_irq();
    return ret;
}

static void input_isr_d0(void* _ctx) {
    WIEGAND* _this = static_cast<WIEGAND*>(_ctx);
    _this->ReadD0();
}

static void input_isr_d1(void* _ctx) {
    WIEGAND* _this = static_cast<WIEGAND*>(_ctx);
    _this->ReadD1();
}

void WIEGAND::begin() {
    _lastWiegand = 0;
    _cardTempHigh = 0;
    _cardTemp = 0;
    _code = 0;
    _wiegandType = 0;
    _bitCount = 0;

    const GpioPin* pinD0 = &gpio_ext_pa6;
    const GpioPin* pinD1 = &gpio_ext_pa7;

    hal_gpio_init_simple(pinD0, GpioModeInterruptFall); // Set D0 pin as input
    hal_gpio_init_simple(pinD1, GpioModeInterruptFall); // Set D1 pin as input

    hal_gpio_add_int_callback(pinD0, input_isr_d0, this);
    hal_gpio_add_int_callback(pinD1, input_isr_d1, this);
}

void WIEGAND::end() {
    hal_gpio_remove_int_callback(&gpio_ext_pa6);
    hal_gpio_remove_int_callback(&gpio_ext_pa7);

    hal_gpio_init_simple(&gpio_ext_pa6, GpioModeAnalog);
    hal_gpio_init_simple(&gpio_ext_pa7, GpioModeAnalog);
}

void WIEGAND::ReadD0() {
    _bitCount++; // Increament bit count for Interrupt connected to D0
    if(_bitCount > 31) // If bit count more than 31, process high bits
    {
        _cardTempHigh |= ((0x80000000 & _cardTemp) >> 31); //	shift value to high bits
        _cardTempHigh <<= 1;
        _cardTemp <<= 1;
    } else {
        _cardTemp <<= 1; // D0 represent binary 0, so just left shift card data
    }
    _lastWiegand = DWT->CYCCNT; // Keep track of last wiegand bit received
}

void WIEGAND::ReadD1() {
    _bitCount++; // Increment bit count for Interrupt connected to D1
    if(_bitCount > 31) // If bit count more than 31, process high bits
    {
        _cardTempHigh |= ((0x80000000 & _cardTemp) >> 31); // shift value to high bits
        _cardTempHigh <<= 1;
        _cardTemp |= 1;
        _cardTemp <<= 1;
    } else {
        _cardTemp |= 1; // D1 represent binary 1, so OR card data with 1 then
        _cardTemp <<= 1; // left shift card data
    }
    _lastWiegand = DWT->CYCCNT; // Keep track of last wiegand bit received
}

unsigned long WIEGAND::GetCardId(
    volatile unsigned long* codehigh,
    volatile unsigned long* codelow,
    char bitlength) {
    if(bitlength == 26) // EM tag
        return (*codelow & 0x1FFFFFE) >> 1;

    if(bitlength == 24) return (*codelow & 0x7FFFFE) >> 1;

    if(bitlength == 34) // Mifare
    {
        *codehigh = *codehigh & 0x03; // only need the 2 LSB of the codehigh
        *codehigh <<= 30; // shift 2 LSB to MSB
        *codelow >>= 1;
        return *codehigh | *codelow;
    }

    if(bitlength == 32) {
        return (*codelow & 0x7FFFFFFE) >> 1;
    }

    return *codelow; // EM tag or Mifare without parity bits
}

char translateEnterEscapeKeyPress(char originalKeyPress) {
    switch(originalKeyPress) {
    case 0x0b: // 11 or * key
        return 0x0d; // 13 or ASCII ENTER

    case 0x0a: // 10 or # key
        return 0x1b; // 27 or ASCII ESCAPE

    default:
        return originalKeyPress;
    }
}

bool WIEGAND::DoWiegandConversion() {
    unsigned long cardID;
    unsigned long sysTick = DWT->CYCCNT;

    if((sysTick - _lastWiegand) >
       (25 * clocks_in_ms)) // if no more signal coming through after 25ms
    {
        if((_bitCount == 24) || (_bitCount == 26) || (_bitCount == 32) || (_bitCount == 34) ||
           (_bitCount == 37) || (_bitCount == 40) || (_bitCount == 8) ||
           (_bitCount ==
            4)) // bitCount for keypress=4 or 8, Wiegand 26=24 or 26, Wiegand 34=32 or 34
        {
            _codeHigh = 0;
            // shift right 1 bit to get back the real value - interrupt done 1 left shift in advance
            _cardTemp >>= 1;
            // bit count more than 32 bits, shift high bits right to make adjustment
            if(_bitCount > 32) _cardTempHigh >>= 1;

            if(_bitCount == 8) // keypress wiegand with integrity
            {
                // 8-bit Wiegand keyboard data, high nibble is the "NOT" of low nibble
                // eg if key 1 pressed, data=E1 in binary 11100001 , high nibble=1110 , low nibble = 0001
                char highNibble = (_cardTemp & 0xf0) >> 4;
                char lowNibble = (_cardTemp & 0x0f);
                _wiegandType = _bitCount;
                _bitCount = 0;
                _cardTemp = 0;
                _cardTempHigh = 0;

                if(lowNibble ==
                   (~highNibble & 0x0f)) // check if low nibble matches the "NOT" of high nibble.
                {
                    _code = (int)translateEnterEscapeKeyPress(lowNibble);
                    return true;
                } else {
                    _lastWiegand = sysTick;
                    _bitCount = 0;
                    _cardTemp = 0;
                    _cardTempHigh = 0;
                    return false;
                }

                // TODO: Handle validation failure case!
            } else if(4 == _bitCount) {
                // 4-bit Wiegand codes have no data integrity check so we just
                // read the LOW nibble.
                _code = (int)translateEnterEscapeKeyPress(_cardTemp & 0x0000000F);

                _wiegandType = _bitCount;
                _bitCount = 0;
                _cardTemp = 0;
                _cardTempHigh = 0;

                return true;
            } else if(40 == _bitCount) {
                _cardTempHigh >>= 1;

                _code = _cardTemp;
                _codeHigh = _cardTempHigh;

                _wiegandType = _bitCount;
                _bitCount = 0;
                _cardTemp = 0;
                _cardTempHigh = 0;

                return true;
            } else {
                // wiegand 26 or wiegand 34
                cardID = GetCardId(&_cardTempHigh, &_cardTemp, _bitCount);
                _wiegandType = _bitCount;
                _bitCount = 0;
                _cardTemp = 0;
                _cardTempHigh = 0;
                _code = cardID;
                return true;
            }
        } else {
            // well time over 25 ms and bitCount !=8 , !=26, !=34 , must be noise or nothing then.
            _lastWiegand = sysTick;
            _bitCount = 0;
            _cardTemp = 0;
            _cardTempHigh = 0;
            return false;
        }
    } else
        return false;
}