#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <inttypes.h>
#include <time.h>

typedef uint64_t U64;

struct timespec
diff_time( struct timespec end, struct timespec start )
{
    struct timespec res;

    res.tv_sec = end.tv_sec - start.tv_sec;
    res.tv_nsec = end.tv_nsec - start.tv_nsec;

    if ( res.tv_nsec < 0 ) {
        res.tv_nsec += 1000 * 1000 * 1000;
        res.tv_sec  -= 1;
    }

    return res;
}

U64 gcd( U64 a, U64 b ) {
    return !b ? a : gcd( b, a % b );
}

U64 lcm( U64 a, U64 b ) {
    return a * b / gcd( a, b );
}

U64 gcm( U64 max, U64 n ) {
    U64 c, lcm;

    for( c = 1; ( ~n & 1 ) && ( c < 4096 ); c <<= 1 ) n >>= 1;
    lcm = n * 4096;
    return ( max / lcm ) * lcm;
}

#define GB ( 1024ull * 1024ull * 1024ull )
#define PAGE 4096

int main(int argc, char **argv) {
    U64 r, chk;
    U64 s = argc > 1 ? strtoull( argv[1], NULL, 10 ) : GB;

    struct timespec start, end, difft;

    clock_gettime( CLOCK_PROCESS_CPUTIME_ID, &start );
    for( chk = 0, r = 1; r < ( s >> 1 ); ++r ) {
        chk += gcm( s, r );
    }
    clock_gettime( CLOCK_PROCESS_CPUTIME_ID, &end );
    difft = diff_time( end, start );

    printf( "anonyM: gcm for s=%"
            PRIu64
            " & r=1 to %"
            PRIu64
            " took:%lld secs %ld nsecs\n"
            "chk = %" PRIu64 "\n",
            s, s>>1, (long long) difft.tv_sec, difft.tv_nsec, chk );


    clock_gettime( CLOCK_PROCESS_CPUTIME_ID, &start );
    for( chk = 0, r = 1; r < ( s >> 1 ); ++r ) {
        chk += s - ( s % lcm( r, 4096 ) );
    }
    clock_gettime( CLOCK_PROCESS_CPUTIME_ID, &end );
    difft = diff_time( end, start );

    printf( "oiskuu: gcm for s=%"
            PRIu64
            " & r=1 to %"
            PRIu64
            " took:%lld secs %ld nsecs\n"
            "chk = %" PRIu64 "\n",
            s, s>>1, (long long) difft.tv_sec, difft.tv_nsec, chk );

    return 0;
}
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