Arduino Math using Nano

Projects Programming
22

The following code works and gives me the long long result that i wanted. It isn't pretty, but at least I can move on to other tasks. Thanks to all who helped.

unsigned long long ReceiverFreq = 147165000;
char strfreq[11];     // empty string
char *ptr = strfreq; //

void setup()

{
  Serial.begin(57600);
  ReceiverFreq = ReceiverFreq - 10700000;
  ReceiverFreq = ReceiverFreq / 3 ;
  //ReceiverFreq = 454883300; // this is what I want to send to my si5351
  ltoa(ReceiverFreq, strfreq, 10);
  String zeros = "00";
  String  FinalFreq = strfreq + zeros ;
  FinalFreq.toCharArray(strfreq, 11);

  ReceiverFreq = char2LL(ptr);
  Serial.println();
  Serial.println("rec freq ");

  printULL(ReceiverFreq);

}

void loop() {

}
void printULL(unsigned long long value)
{
  if (value == 0)
    return;
  printULL(value / 10);
  Serial.print(int(value % 10));
}
long long char2LL(char *str)
{
  long long result = 0; // Initialize result
  // Iterate through all characters of input string and update result
  for (int i = 0; str[i] != '\0'; ++i)
    result = result * 10 + str[i] - '0';
  return result;
}
23

The following printULL() subroutine of post #15 works well for value > 0. If the passed value is 0, it can't be printed. How can 0 be printed?

void printULL(unsigned long long value)
{
  if (value == 0)
    return;
  printULL(value/10);
  Serial.print(int(value % 10));
}
24

That is left as an exercise for the reader.

25

Noted down!

26 
void printULL(uint64_t value) {
  if (value) {
    for (uint64_t v = 10000000000000000000ull; v; v /= 10) {
      if (v <= value) {
        Serial.print((int)(value / v % 10));
      }
    }
    return;
  }
  Serial.print(0);
}

Less elegant, but nice when you are short on stack space.

Show 11 digit number on 7-segment displays
27

Tested for 0, 1, and 18446744073709551615; your subroutine is working fine!
Congratulation!

28

Sweet. Thank you.

29

What is about the following one?

void printULL(uint64_t value)
{
  int i = 0;
  byte myBCD[25];

  do
  {
    myBCD[i] = value % 10;
    value = value / 10;
    i++;
  }
  while (value != 0);
  for (int j = i - 1; j >= 0; j--)
  {
    Serial.print(myBCD[j]);
  }
}
30

It is sort of the reverse of the previous one.

31

Both you and @johnwasser have used % and / operators to extract the BCD digits and then just print them on the Serial Monitor. I have also used the same operators and the attempt came on the way of trying to understand @jfjlaros and @johnwasser program logic.

32

Well, it certainly works.

33

Nope.

I know you are obsessed with BCD, but this problem has nothing to do with BCD.

34

I mean --
Given:

byte y = 0x35;  //53
byte r1 = y%10; //r1 = 00000011 = unpacked BCD
35

Again nope.

For BCD you would mask and shift, not divide by ten.

So you basically fell for an incorrect comment?
Or did you make that comment yourself?

36

I have done the modulus (%) operation and not the division (/) to get the unpacked BCD.

37

You are using the remainder of the division, so you divide.

No, you don't get any unpacked BCD.

I think the obsession and the missing understanding of BCD is a strange combination.

38

% operator is doing the above task; as a result, I get 00000011 and 00000101 from 0x35.

byte y = 0x35;
byte r1 = y%10;   //r1 = 00000011
y = y/10;
byte r2 = y%10;  //r2 = 00000101
39

There is a division involved in getting the remainder.

BTW 0x35 would yield "35" if it really was BCD.

40

A BCD number, by definition, is a 4-bit binary for the decimal digits: 0 to 9. If we want to store them into computer memory, they have to be formatted into 8-bit unpacked (like 00000011 and 00000101) BCD numbers or packed BCD numbers (like 00110101 or 01010011).

65535 (to my eyes it is a decimal number) can be stored in computer memory as:

1111 1111 1111 1111 (the binary format)

binary2

or

0110 0101 0101 0011 0101 (the BCD format)

bcd3byte

41

Nope, BCD is a coding that uses only 0-9 for the digits, but 16 as the base.

The problem was the conversion of a long long binary into decimal representation.

Have a nice day and don't see BCD anywhere you see decimal digits.

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