Fastest way to convert binary to decimal?

Question

I\'ve got four unsigned 32-bit integers representing an unsigned 128-bit integer, in little endian order:

typedef struct {
    unsigned int part[4];
} bigint         


        

Answer 1

If your values are mostly less than ULLONG_MAX (18446744073709551615) I'd try to use for them sprintf(buf,"%llu",ullong_val). I bet this is rather well optimized in standard library, but parsing of format will take some cycles though.

Otherwise I'd create a bigint_divmod1000000000 (or better name mod10to9) function and use that. It would need 9 times less divides than bigint_divmod10.