#include <stdio.h>
#include <stdlib.h>
#include <string.h>

short date_compress(int day, int month, int year) {
    short d = ((((year % 100) << 4) + month) << 5) + day;
    return d;
}

int* date_decompress(int cdate) {
    static int d[3];

    d[0] = cdate & 0x1f;
    d[1] = (cdate >> 5) & 0xf;
    d[2] = 2000 + (cdate >> (5 + 4));

    return d;
}

short time_compress(int hour, int minute, int second) {
    short t = (((second << 6) + minute) << 4) + hour;
    return t;
}

int* time_decompress(int ct) {
    static int t[3];

    t[0] = ct & 0xf;
    t[1] = (ct >> 4) & 0x3f;
    t[2] = (ct >> 10) & 0x3f;

    return t;
}

int date_time_compress(int day, int month, int year, int hour, int minute, int second) {
    int dt = (date_compress(day, month, year) << 16) + time_compress(hour, minute, second);
    return dt;
}

int* date_time_decompress(int dtc) {
    int* dt = malloc(8 * sizeof(int));

    memcpy(dt, date_decompress(dtc >> 16), 4 * sizeof(int));
    memcpy(dt + 3, time_decompress(dtc), 4 * sizeof(int));

    return dt;
}

int main()
{
    int day = 21;
    int month = 3;
    int year = 2019;

    int hour = 10;
    int minute = 27;
    int second = 24;

    printf("Eingabedaten\n");
    printf("Datum: %i/%i/%i\n", day, month, year);
    printf("Uhrzeit: %i/%i/%i\n\n", hour, minute, second);

    short date_compressed = date_compress(day, month, year);
    printf("Datum Komprimiert:");
    printf("%#06x\n", date_compressed);

    int *date_decompressed = date_decompress(date_compressed);
    printf("Datum Dekomprimiert:");
    printf("%i/%i/%i\n\n",
				*date_decompressed, 		// day
				*(date_decompressed + 1), 	// month
				*(date_decompressed + 2));	// year

    short time_compressed = time_compress(hour, minute, second);
    printf("Uhrzeit Komprimiert:");
    printf("%#06x\n", time_compressed);

    int *time_decompressed = time_decompress(time_compressed);
    printf("Uhrzeit Dekomprimiert:");
    printf("%i/%i/%i\n\n",
				*time_decompressed, 		// hour
				*(time_decompressed + 1), 	// minute
				*(time_decompressed + 2));	// second

    int date_time_compressed = date_time_compress(day, month, year, hour, minute, second);
    printf("Datum/Uhrzeit Komprimiert:");
    printf("%#06x\n", date_time_compressed);

    int *date_time_decompressed = date_time_decompress(date_time_compressed);
    printf("Datum/Uhrzeit Dekomprimiert:");
    printf("%i/%i/%i %i/%i/%i\n\n",
				*date_time_decompressed, 		// day
				*(date_time_decompressed + 1), 	// month
				*(date_time_decompressed + 2), 	// year
				*(date_time_decompressed + 3), 	// hour
				*(date_time_decompressed + 4), 	// minute
				*(date_time_decompressed + 5));	// second

    return 0;
}