[3DS] GW Decrypter

#define _CRT_SECURE_NO_WARNINGS true

#include <cstdio>
#include <memory>

void main() {
        //Load ROP
        FILE *IFile = fopen("Launcher.dat", "rb+");
        fseek(IFile, 0, SEEK_END);
        int bSize = ftell(IFile) > 0x4000 ? 0x4000 : ftell(IFile); //Limit 0x4000 bytes size
        fseek(IFile, 0, SEEK_SET);
        int *buffer = (int*)malloc(0x4000);
        fread(buffer, 1, bSize, IFile);
        fclose(IFile);

        //Encrypt ROP
        for (int state = 0xD5828281, i = 0; i < 0x4000 / 4; i++, state += 0xD5828281)
                buffer[i] += state;

        //Save ROP
        IFile = fopen("decLauncher.dat", "wb+");
        fseek(IFile, 0x00012000, SEEK_SET); //4.X Users
        fwrite(buffer, 1, 0x4000, IFile);
        fseek(IFile, 0x0001A000, SEEK_SET); //5.X+ Users
        fwrite(buffer, 1, 0x4000, IFile);
        fclose(IFile);

        free(buffer);
}