Binary string isn't converting to decimal properly on my Arduino - c++

Question

I want to convert a binary string I store from my two interrupts (ISR_INT1, ISR_INT0) into a decimal. I've tested this using gcc on my Mac and it works well, giving me the correct decimal. Testing on my Arduino I get a totally different decimal. I know the Arduino only goes up to 16-bit ints so I used a long instead see below. Any help or suggestions are greatly appreciated.
Here is my Arduino sketch:
#define MAX_BITS 100 // max number of bits
#define WEIGAND_WAIT_TIME 3000 // time to wait for another weigand pulse.
unsigned char databits[MAX_BITS]; // stores all of the data bits
unsigned char bitCount; // number of bits currently captured
unsigned char flagDone; // goes low when data is currently being captured
unsigned int weigand_counter; // countdown until we assume there are no more bits
unsigned long facilityCode = 0; // decoded facility code
unsigned long cardCode = 0; // decoded card code
String fullCard; // binary value full card number
int LED_GREEN = 11;
int LED_RED = 12;
int BEEP_BEEP = 10;
// interrupt that happens when INTO goes low (0 bit)
void ISR_INT0() {
fullCard += 0;
bitCount++;
flagDone = 0;
weigand_counter = WEIGAND_WAIT_TIME;
}
// interrupt that happens when INT1 goes low (1 bit)
void ISR_INT1() {
fullCard += 1;
databits[bitCount] = 1;
bitCount++;
flagDone = 0;
weigand_counter = WEIGAND_WAIT_TIME;
}
void setup() {
pinMode(LED_RED, OUTPUT);
pinMode(LED_GREEN, OUTPUT);
pinMode(BEEP_BEEP, OUTPUT);
digitalWrite(LED_RED, HIGH); // High = Off
digitalWrite(BEEP_BEEP, HIGH); // High = off
digitalWrite(LED_GREEN, LOW); // Low = On
pinMode(2, INPUT); // DATA0 (INT0)
pinMode(3, INPUT); // DATA1 (INT1)
Serial.begin(9600);
Serial.println("Snow RFID Reader PUT HID CARD ");
// binds the ISR functions to the falling edge of INTO and INT1
attachInterrupt(0, ISR_INT0, FALLING);
attachInterrupt(1, ISR_INT1, FALLING);
weigand_counter = WEIGAND_WAIT_TIME;
}
void loop() {
// This waits to make sure that there have been no more data pulses before processing data
if (!flagDone) {
if (--weigand_counter == 0)
flagDone = 1;
}
// if we have bits and we the weigand counter went out
if (bitCount > 0 && flagDone) {
unsigned char i;
Serial.print(" ");
Serial.print("Read ");
Serial.print(bitCount);
Serial.print(" bits. ");
Serial.print(fullCard);
**// THIS IS WHERE IT I TRY TO CONVERT MY BINARY STRING INTO A DECIMAL**
long fullCardInt = bin2dec(const_cast<char*>(fullCard.c_str()));
Serial.print(fullCardInt);
if (bitCount == 35) {
// 35 bit HID Corporate 1000 format
// facility code = bits 2 to 14
for (i = 2; i < 14; i++) {
facilityCode <<= 1;
facilityCode |= databits[i];
}
// card code = bits 15 to 34
for (i = 14; i < 34; i++) {
cardCode <<= 1;
cardCode |= databits[i];
}
printBits();
} else if (bitCount == 26) {
// standard 26 bit format
// facility code = bits 2 to 9
for (i = 1; i < 9; i++) {
facilityCode <<= 1;
facilityCode |= databits[i];
}
// card code = bits 10 to 23
for (i = 9; i < 25; i++) {
cardCode <<= 1;
cardCode |= databits[i];
}
printBits();
} else {
Serial.println("Unable to decode.");
}
// cleanup and get ready for the next card
bitCount = 0;
facilityCode = 0;
cardCode = 0;
for (i = 0; i < MAX_BITS; i++) {
databits[i] = 0;
}
}
}
void printBits() {
Serial.print("FC = ");
Serial.print(facilityCode);
Serial.print(", CC = ");
Serial.println(cardCode);
digitalWrite(LED_RED, LOW); // Red
if (cardCode == 12345) {
digitalWrite(LED_GREEN, HIGH);
}
delay(500);
digitalWrite(LED_RED, HIGH);
digitalWrite(LED_GREEN, LOW);
digitalWrite(BEEP_BEEP, LOW);
delay(500);
digitalWrite(BEEP_BEEP, HIGH);
delay(500);
digitalWrite(BEEP_BEEP, LOW);
delay(500);
digitalWrite(BEEP_BEEP, HIGH);
}
long bin2dec(const char *bin) {
int result = 0;
for (; *bin; bin++) {
if ((*bin != '0') && (*bin != '1'))
return -1;
result = result * 2 + (*bin - '0');
//if(result<=0) return -1;
}
return result;
}
This is what my serial terminal for my Arduino reads out
Snow RFID Reader PUT HID CARD
// bits read Binary string Incorrect decimal
Read 26 bits. 00001000000100000101010011 16723 FC = 16, CC = 8361
Here is my Test.cpp script
//THIS WORKS AND GIVES ME THE CORRECT DECIMAL
#include <stdio.h>
int bin2dec(const char *bin) {
int result=0;
for(;*bin;bin++) {
if((*bin!='0')&&(*bin!='1'))
return -1;
result=result*2+(*bin-'0');
}
return result;
}
int main (void) {
printf("%d\n", bin2dec("00001000000100000101010011"));
return(0);
}
This is what my test cpp script gives me which is correct.
S:g$ g++ main.cpp -o SnowTest
S:g$ ./SnowTest
2113875

Answer 1

As you said, int on Arduino are 16 bit.
Inside your function int bin2dec, you return an int and result is a int, so in Arduino your number is truncated to the 16 lsb (100000101010011) that in dec are 16723.
Use long instead
long bin2dec(const char *bin)
{
long result=0;
for(;*bin;bin++)
{
if((*bin!='0')&&(*bin!='1'))
return -1;
result=result*2+(*bin-'0');
//if(result<=0) return -1;
}
return result;
}