Centurion packer

[Darasco]

Hello, good afternoon. I am trying to translate the centurion game. There are several compressed files supposedly in lzw. I have got a decompressor made in C, that works. But, the files need to be compressed again. Using the same algorithm would it be possible to make a compressor? thanks for the help. I will leave an example file and the code.

[jotd]

In a compressor/decompressor algorithm, the decompressor is the easy part. Writing the compressor is not easy and there are several possiblities to compute the dictionary, not just one. Did you write the decompressor yourself?

[Darasco]

I didn't do it. I just looked it up. But I haven't found a compressor. Ok, thanks anyway.

[paraj]

It shouldn't be too bad of such a simple encoding. You can probably adapt an existing encoder quite easily. If you you're not pressed for size, start out with just a really stupid one that encodes everything as literals.

[Darasco]

mmm. thanks. i'll try a couple of things.

[paraj]

Like this I mean (terrible code, but should decompress to the same thing):

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

uint8_t outbuf[1024*1024];
uint8_t* mode_ptr = &outbuf[0];
int mode_cnt = 0;
size_t outbuf_pos = 1;

int main(int argc, char* argv[])
{
    if (argc != 3) {
        fprintf(stderr, "Usage: %s in out\n", argv[0]);
        return 1;
    }

    FILE* in = fopen(argv[1], "rb");
    if (!in) {
        fprintf(stderr, "Could not open %s\n", argv[1]);
        return -1;
    }
    uint8_t* data;
    uint32_t data_len;

    fseek(in, 0, SEEK_END);
    data_len = (uint32_t)ftell(in);
    fseek(in, 0, SEEK_SET);
    data = (uint8_t*)malloc(data_len); // Let's assume this works
    fread(data, data_len, 1, in);
    fclose(in);

    FILE* out = fopen(argv[2], "wb");
    if (!out) {
        fprintf(stderr, "Could not create %s\n", argv[2]);
        return -1;
    }
    fputc((data_len>>24)&0xff, out);
    fputc((data_len>>16)&0xff, out);
    fputc((data_len>>8)&0xff, out);
    fputc((data_len>>0)&0xff, out);

    for (uint32_t i = 0; i < data_len; ++i) {
        if (mode_cnt == 8) {
            mode_cnt = 0;
            mode_ptr = &outbuf[outbuf_pos++];
        }
        *mode_ptr = *mode_ptr << 1 | 1;
        ++mode_cnt;
        outbuf[outbuf_pos++] = data[i];
    }

    fwrite(outbuf, outbuf_pos, 1, out);
    fclose(out);
    return 0;
}

[Darasco]

Thank you very much. I'll try it right now. Anyway I've tested adding a fake header to the decompressed file and it seems to read it, although the texts don't match where they should be, but it reads it for sure.

[Darasco]

It workssss!!!. there are no words to thank you