64 Bits integer numbers

The ISO 11784 norm for animal identification code Idf number on 38 bits so we need a data type greater than
unsigned long.
I ask for 64 bits because a 38 bits data type may not exist!

Sorry, I should have guessed it would be something like this.
It's no easy task - to convert a 38-bit number into decimal. Octal and hexadecimal numbers suit much better because conversion routines for them are quite straightforward.
I'm afraid in case of decimals one would have to re-invent integer arithmetics for 38-bit numbers.
good luck
mike

How about this method. You will need to define an array of 38 elements. Each element is an unsigned long. Each element n is initialised to 2 to the power of n+1 and uses BCD representation.

= { 0x00000001,
    0x00000002,
    0x00000004,
    0x00000008,
    0x00000016,
    0x00000032....etc. }

Out of curiosity I came up with the following code to convert n binary digits to m decimal digits. This is the essence of a solution which may be readily adapted to your specific needs.

The code includes a number of test examples.

It compiles to reasonably efficient code, although making use of memory specific pointers would be much better than generic pointers.

#define	BINARY_DIGITS	38
#define	DECIMAL_DIGITS	12
//															                    1                   2                   3
//															0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 
xdata	unsigned char big_binary_00[ BINARY_DIGITS ] 	= { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 };
xdata	unsigned char big_binary_01[ BINARY_DIGITS ] 	= { 1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 };
xdata	unsigned char big_binary_10[ BINARY_DIGITS ] 	= { 0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 };
xdata	unsigned char big_binary_16[ BINARY_DIGITS ] 	= { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 };
xdata	unsigned char big_binary_38[ BINARY_DIGITS ] 	= { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1 };
xdata	unsigned char big_binary_xx[ BINARY_DIGITS ] 	= { 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1 };

xdata	unsigned char big_decimal[ DECIMAL_DIGITS ];

void conversion( unsigned char *binary, unsigned char *decimal )
{
	unsigned char	loop;
	unsigned char	outer_loop;
	unsigned char	*d;
	unsigned char	*t;
	unsigned char	carry = 0;
	unsigned char	temp[ DECIMAL_DIGITS ];

	//
	//	Initialise Data
	//

	loop = DECIMAL_DIGITS;
	d = decimal;
	t = &temp[ 0 ];

	do
	{

		*t = 0;
		t++;
		*d = 0;
		d++;
		
	}while( --loop != 0 );	

	temp[ 0 ] = 1;


	outer_loop = BINARY_DIGITS;

	do
	{
		if( *binary != 0 )
		{
	
			//
			//	Set d to d plus t
			//
		
			loop = DECIMAL_DIGITS;
			carry = 0;
			t = &temp[ 0 ];
			d = &decimal[ 0 ];
		
			do
			{
				*d = (*d + *t) + carry;
		
				if( *d < 10 )
				{
					carry = 0;
				}
				else
				{
					*d = *d - 10;
					carry = 1;
				}
		
				d++;
				t++;
		
			}while( --loop != 0 );	
			
		
		}
	
		//
		//	Double the BCD value in t
		//
		
		loop = DECIMAL_DIGITS;
		carry = 0;
		t = &temp[ 0 ];
		
		do
		{
			*t = (*t * 2) + carry;
		
			if( *t < 10 )
			{
				carry = 0;
			}
			else
			{
				*t = *t - 10;
				carry = 1;
			}
		
			t++;		
		
		}while( --loop != 0 );

		binary++;

	}while( --outer_loop != 0 );	

}




main( void )
{
	conversion( &big_binary_00, &big_decimal );
	conversion( &big_binary_01, &big_decimal );
	conversion( &big_binary_10, &big_decimal );
	conversion( &big_binary_16, &big_decimal );
	conversion( &big_binary_38, &big_decimal );

	conversion( &big_binary_xx, &big_decimal );
	conversion( &big_binary_xx, &big_decimal );
}