BWB2W2 elfcrypt

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

int main(int argc, char** argv)
{
    printf("\nelfcrypt - tool to decrypt/encrypt Entralink Forest data\n");
    if(argc != 3)
    {
        printf("\nUsage:\n");
        printf("elfcrypt.exe INFILE OUTFILE\nFilesize must be 2128 (0x850) bytes\n\n");
        printf("Save data offset:\n0x22C00 (BW)\n0x22A00 (B2W2)\n\n");
        return 0;
    }

    FILE *fp;
    fp = fopen(argv[1], "rb");
    if (!fp)
    {
        printf("\nFile loading failed!\n\n");
        return 0;
    }

    fseek (fp, 0, SEEK_END);
    int fSize = ftell(fp);
    rewind (fp);

    if(fSize != 0x850)
    {
        printf("\nWrong file size! Entralink Forest data should be 2128 (0x850) bytes.\n\n");
        return 0;
    }

    char *data;
    data = (char *)malloc(0x850);
    fread(data, 1, 0x850, fp);
    fclose(fp);

    unsigned long seed = ((data[0x84C] & 0xFF) + ((data[0x84D] & 0xFF) << 8) + ((data[0x84E] & 0xFF) << 16) + ((data[0x84F] & 0xFF) << 24));

    int x;
    unsigned int temp;
    for(x = 0; x < 0x426; x++)
    {
        seed = (0x41C64E6D * seed + 0x6073);
        temp = ((data[2*x] & 0xFF) + ((data[2*x+1] & 0xFF) << 8)) ^ (seed >> 16);

        data[2*x] = temp;
        data[2*x+1] = temp >> 8 ;
    }

    fp = fopen(argv[2], "wb+");
    if (!fp)
    {
        printf("\nWriting new file failed!\n\n");
        return 0;
    }

    fwrite(data, 1, 0x850, fp);
    free(data);
    fclose(fp);

    printf("\nDone!\n\n");
    return 0;
}