Tooltron

#include <string.h>

#include <stdint.h>

#include <util/delay.h>

#include "rfid.h"

#include "serial.h"

#define MF_SELECT_CMD 0x83

static uint8_t select_cmd[] = {0xFF, 0, 1, MF_SELECT_CMD, MF_SELECT_CMD + 1};

#define FRAME_SIZE(data_size) ((data_size)+4)

#define RFID_DATA_SIZE (RFID_SERNO_SIZE+2)

#define MAX_FRAME_SIZE FRAME_SIZE(RFID_DATA_SIZE)

#define RESP_START    0

#define RESP_RESERVED 1

#define RESP_LENGTH   2

#define RESP_CMD      3

#define RESP_DATA     4

static uint8_t response[MAX_FRAME_SIZE];

static uint8_t resp_idx;

static uint8_t serno[RFID_SERNO_SIZE];

static void zero_serno() {

  int i;

  for (i = 0; i < RFID_SERNO_SIZE; i++) {

    serno[i] = 0;

  }

}

void rfid_init() {

  serial_init();

}

void rfid_start_read() {

  resp_idx = 0;

  serial_flush();

  serial_write(select_cmd, sizeof(select_cmd));

}

char parse_response() {

  uint8_t sum;

  int resp_csum, i;

  if (response[RESP_CMD] != MF_SELECT_CMD) {

    // invalid response, ignore

    zero_serno();

    return 0;

  }

  if (response[RESP_LENGTH] != RFID_DATA_SIZE) {

    // wrong response length, assume there's no card

    zero_serno();

    return 1;

  }

  resp_csum = response[RESP_LENGTH] + RESP_CMD;

  sum = 0;

  for (i = RESP_LENGTH; i < resp_csum; i++) {

    sum += response[i];

  }

  if (response[resp_csum] != sum) {

    zero_serno();

    return 0;

  }

  memcpy(serno, &response[RESP_DATA+1], RFID_SERNO_SIZE);

  return 1;

}

char rfid_poll() {

  int c;

  while ((c = serial_read()) >= 0) {

    if (resp_idx < sizeof(response)) {

      response[resp_idx] = c;

    }

    resp_idx++;

    if (resp_idx == 1) {

      // restart if the frame start is invalid

      if (response[RESP_START] != 0xFF) {

        resp_idx = 0;

      }

    } else if (resp_idx > RESP_LENGTH) {

      // check if we're done with current packet

      if (resp_idx >= FRAME_SIZE(response[RESP_LENGTH])) {

        rfid_start_read();

        if (parse_response()) {

          return 1;

        }

      }

    }

  }

  return 0;

}

void rfid_get_serno(uint8_t *buf) {

  memcpy(buf, serno, sizeof(serno));

}