Did you ever saw a char and thought: “Damn, 1 byte for a single char is pretty darn inefficient”? No? Well I did. So what I decided to do instead is to pack 5 chars, convert each char to a 2 digit integer and then concat those 5 2 digit ints together into one big unsigned int and boom, I saved 5 chars using only 4 instead of 5 bytes. The reason this works is, because one unsigned int is a ten digit long number and so I can save one char using 2 digits. In theory you could save 32 different chars using this technique (the first two digits of an unsigned int are 42 and if you dont want to account for a possible 0 in the beginning you end up with 32 chars). If you would decide to use all 10 digits you could save exactly 3 chars. Why should anyone do that? Idk. Is it way to much work to be useful? Yes. Was it funny? Yes.

Anyone whos interested in the code: Heres how I did it in C: https://pastebin.com/hDeHijX6

Yes I know, the code is probably bad, but I do not care. It was just a funny useless idea I had.

  • ChaoticNeutralCzech@feddit.orgEnglish
    8·
    1 day ago
    unsigned int turn_char_to_int(char pChar)
{
    switch(pChar)
    {
    case 'a':
        return 10;
    case 'b':
        return 11;
    case 'c':
        return 12;
    case 'd':
        return 13;
    case 'e':
        return 14;
    case 'f':
        return 15;
    case 'g':
        return 16;
    case 'h':
        return 17;
    case 'i':
        return 18;
    case 'j':
        return 19;
    case 'k':
        return 20;
    case 'l':
        return 21;
    case 'm':
        return 22;
    case 'n':
        return 23;
    case 'o':
        return 24;
    case 'p':
        return 25;
    case 'q':
        return 26;
    case 'r':
        return 27;
    case 's':
        return 28;
    case 't':
        return 29;
    case 'u':
        return 30;
    case 'v':
        return 31;
    case 'w':
        return 32;
    case 'x':
        return 33;
    case 'y':
        return 34;
    case 'z':
        return 35;
    case ' ':
        return 36;
    case '.':
        return 37;

    }
}

    Are you a monster or just stupid?

      • ChaoticNeutralCzech@feddit.orgEnglish
        2·
        1 day ago

        If you couldn’t write

        if(pChar >= 'a' && pChar <= 'z') return pChar - ('a' - 10);

        I suppose you typed this “all the size of a lookup table with none of the speed” abomination manually too.

        • Zacryon@feddit.org
          3·
          1 day ago

          switch case structures are very efficient in c and c++. They work similarly like an offset into memory. Compute the offset once (any expression in the ‘case’ lines), then jump. Using primitives directly, like here with chars, is directly the offset. Contrary to if-else branches, where each case must be evaluated first and the CPU has basically no-op cycles in the pipeline until the result of the branch is known. If it fails, it proceeds with the next one, waits again etc… (Some CPU architectures might have stuff like speculative branch execution, which can speed this up.)

          However, code-style wise this is really not elegant and something like your proposal or similar would be much better.

          • ChaoticNeutralCzech@feddit.orgEnglish
            2·
            24 hours ago

            Oh, I didn’t know that they were a LUT of jump addresses. Stil, a LUT of values would be more space-efficient and likely faster. Also, what if the values are big and sparse, e.g.

            switch (banknoteValue) {
    case 5000:
        check_uv();
        check_holograph();
    case 2000:
        check_stripe();
    case 1000:
        check_watermark();
}

            …does the compiler make it into an if-else-like machine code instead?