CRC32 Model Recognition Tutorial

[Macpunk]

so, what you're saying is that I could...have an int to have the beginning texture ID, and when I press a button, it would take int and add one to it, all the while coloring texture ID int a different color? As soon as I find what I'm looking for...like the player model colored differently, then I would hit a button, and it would log the current texture ID to a file? That would be cool if it worked like that...

If that's what I need to do...i need to look up coloring player models differently :p.

Thanks,
Macpunk

[silverfish]

old-ass thread but thanks for this...worked in Q4 just for fun in about 3mins.

[Letters]

i prefer this crc cheksume, a bit cleaner and you dont need an object.

( i dont like objects for such tiny stuff )

btw. not by me, so i added the reference.

#ifndef _CRC_
#define _CRC_
// Quelle: http://www.geocities.com/malbrain/  Karl Malbrain
// Usage : v32 = ~crc32_calc (msg, len, ~0U);
/*
 *        calculate ccitt cyclic redundancy codes
 *
 *        actual Crc16 = x ^ 16 + x ^ 12 + x ^ 5 + 1
 *
 *        inverse Crc32 = x ^ 32 + x ^ 31 + x ^ 30 +
 *              x ^ 28 + x ^ 27 + x ^ 25 + x ^ 24 +
 *              x ^ 22 + x ^ 21 + x ^ 20 + x ^ 16 +
 *              x ^ 10 + x ^ 9 + x ^ 6 + 1
 *
 *        n.b. standard ANSI X3.66 crc-32 polynomial:
 *        x^0 + x^1 + x^2 + x^4 + x^5 + x^7 + x^8 + x^10 +
 *        x^11 + x^12 + x^16 + x^22 + x^23 + x^26 + x^32
 *
 *        Tables constructed so that entry 0x80 = inverse polynomial
 */

unsigned short Crc16[] = {
0x0000, 0x1081, 0x2102, 0x3183, 0x4204, 0x5285, 0x6306, 0x7387,
0x8408, 0x9489, 0xa50a, 0xb58b, 0xc60c, 0xd68d, 0xe70e, 0xf78f
};

unsigned long Crc32[] = {
0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c
};

unsigned short crc16_calc (unsigned char *ptr, unsigned cnt, unsigned short crc)
{
    while( cnt-- ) {
        crc = ( crc >> 4 ) ^ Crc16[(crc & 0xf) ^ (*ptr & 0xf)];
        crc = ( crc >> 4 ) ^ Crc16[(crc & 0xf) ^ (*ptr++ >> 4)];
    }
 
    return crc;
}

unsigned long crc32_calc (unsigned char *ptr, unsigned cnt, unsigned long crc)
{
    while( cnt-- ) {
        crc = ( crc >> 4 ) ^ Crc32[(crc & 0xf) ^ (*ptr & 0xf)];
        crc = ( crc >> 4 ) ^ Crc32[(crc & 0xf) ^ (*ptr++ >> 4)];
    }

    return crc;
}
#endif _CRC_

usage is in the code.

[irulehard]

LOL so old thread, would be useful if i can get the crc32.cpp and crc32.h. the link on the first page is broken. help

[Shard]

LOL so old thread, would be useful if i can get the crc32.cpp and crc32.h. the link on the first page is broken. help

The post above yours has an alternative. Also, sorry to say I had very little idea what I was actually doing when I wrote this, it was just a compilation of what people had told me.

There are much better and easier ways of doing checksum based texture recognition than what I described here. There are also better alternatives to using checksums at all, which were little known back then.

[OneSniper]

Thanks for this I will try to use this.

[~Feelipee]

Perfect Shard !
thx man

---------- Post added at 17:51 ---------- Previous post was at 17:50 ----------

Perfect Shard !
thx man