typedef [type] lfds611_atom_t;
To abstract away the differences in word length on different plaforms, liblfds uses a typedef.
The type used should be the unsigned integer type which is the same length in bytes as the pointer type. On 32-bit platforms, this is usually an unsigned long int. On 64-bit platforms, this is usually an unsigned long long int.
You can check by writing a small C program to print the value of sizeof(void *). This gives you the length of the pointer type. Then find the sizeof() the unsigned integer types on your system until you find an unsigned integer type of the same byte length.