HCGE decrypter

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <direct.h>

FILE *fHcgData;
unsigned int hcgKey;
unsigned char hcgAkey[0x10];
int hcgPosition2;
int hcgPosition;
uint8_t hcgRootFilesCount;
int hcgEntryRootOff;
int hcgEntryDirOff;
int hcgEntryFilesOff;

unsigned short hcgeFillAkey() {
  hcgKey = 0x41C64E6D * hcgKey + 12345;
  return (hcgKey >> 16) & 0x7FFF;
}
uint8_t hcgeDecryptByte()
{
    uint8_t kpos = (hcgPosition ^ hcgAkey[((uint8_t)hcgPosition ^ (uint8_t)(hcgPosition >> 4)) & 0xF]) & 0xF;
    char v1 = fgetc(fHcgData);
    char v2 = hcgPosition++;
    return hcgAkey[kpos] ^ v2 ^ v1;
}
uint8_t hcgeDecryptByte2() {
    uint8_t kpos = (hcgPosition2 ^ hcgAkey[((uint8_t)hcgPosition2 ^ (uint8_t)((uint32_t)hcgPosition2 >> 4)) & 0xF]) & 0xF;
    char v1 = fgetc(fHcgData);
    char v2 = hcgPosition2++;
    return hcgAkey[kpos] ^ v2 ^ v1;
}
bool hcgeOpenHcg(char *path) {
    int i;

    FILE *f = fopen(path, "rb");
    if (!f) return false;
    fHcgData = f;

    fseek(f, -0x100C, SEEK_END);
    hcgKey = fgetc(f) << 24;
    fseek(f, 2, SEEK_CUR);
    hcgKey += fgetc(f) << 16;
    fseek(f, 2, SEEK_CUR);
    hcgKey += fgetc(f) << 8;
    fseek(f, 2, SEEK_CUR);
    hcgKey += fgetc(f) << 0;

    for (i = 0; i < 0x10; i++) {
        hcgAkey[i] = hcgeFillAkey();
    }

    fseek(f, -0x100B, SEEK_END);
    hcgPosition2 = ftell(f);
    hcgEntryDirOff = hcgeDecryptByte2() << 24;
    hcgEntryFilesOff = hcgeDecryptByte2() << 24;
    fgetc(fHcgData);
    hcgPosition2++;
    hcgEntryDirOff += hcgeDecryptByte2() << 16;
    hcgEntryFilesOff += hcgeDecryptByte2() << 16;
    fgetc(fHcgData);
    hcgPosition2++;
    hcgEntryDirOff += hcgeDecryptByte2() << 8;
    hcgEntryFilesOff += hcgeDecryptByte2() << 8;
    fgetc(fHcgData);
    hcgPosition2++;
    hcgEntryDirOff += hcgeDecryptByte2();
    hcgEntryFilesOff += hcgeDecryptByte2();
    rewind(fHcgData);

    fseek(fHcgData, hcgEntryDirOff, SEEK_SET);
    hcgPosition2 = hcgEntryDirOff;
    hcgEntryRootOff = hcgeDecryptByte2() << 16;
    hcgEntryRootOff += hcgeDecryptByte2() << 8;
    hcgEntryRootOff += hcgeDecryptByte2();
    hcgEntryRootOff += hcgEntryFilesOff;
    hcgRootFilesCount = hcgeDecryptByte2();
    return true;
}

int Read2(uint8_t *data, int offset) {
    return (data[offset + 0] << 8) | (data[offset + 1] << 8);
}
int Read3(uint8_t *data, int offset) {
    return (data[offset + 0] << 16) | (data[offset + 1] << 8) | (data[offset + 2] << 0);
}
int Read4(uint8_t *data, int offset) {
    return (data[offset + 0] << 24) | (data[offset + 1] << 16) | (data[offset + 2] << 8) | (data[offset + 3] << 0);
}
int main() {
    char buf[0x100];
    if (hcgeOpenHcg("game.hcg")) {
        int i, j, len;
        char buf[0x100];

        fseek(fHcgData, 0, SEEK_END);
        len = ftell(fHcgData);
        rewind(fHcgData);
        hcgPosition = 0;

        uint8_t *dec = (uint8_t*)malloc(len);
        for (i = 0; i < len; i++)
            dec[i] = hcgeDecryptByte();
        fclose(fHcgData);

        int dirsCount = dec[hcgEntryDirOff + 8];
        int dirsOff = hcgEntryDirOff + 11;
        for (i = 0; i < dirsCount; i++) {
            int entryLen = dec[dirsOff];
            char *strDirname = (char*)&dec[dirsOff + 1];
            int strLen = strlen(strDirname);
            int off = Read3(dec, dirsOff + strLen + 2);
            int count = dec[dirsOff + strLen + 5];

            int filesOff = hcgEntryFilesOff + off;
            _mkdir(strDirname);
            for (j = 0; j < count; j++) {
                int fileEntryLen = dec[filesOff];
                char *strFilename = (char*)&dec[filesOff + 1];
                int strLen = strlen(strFilename);
                int off = Read4(dec, filesOff + strLen + 2);
                int len = Read3(dec, filesOff + strLen + 6);
                filesOff += fileEntryLen;


                sprintf(buf, "%s\\%s", strDirname, strFilename);
                printf("%s\n", buf);
                FILE *fOut = fopen(buf, "wb");
                if (fOut) {
                    fwrite(dec + off, 1, len, fOut);
                    fclose(fOut);
                }
            }
            dirsOff += entryLen;
        }

        int rootOff = hcgEntryRootOff;
        for (i = 0; i < hcgRootFilesCount; i++) {
            int fileEntryLen = dec[rootOff];
            char *strFilename = (char*)&dec[rootOff + 1];
            int strLen = strlen(strFilename);
            int off = Read4(dec, rootOff + strLen + 2);
            int len = Read3(dec, rootOff + strLen + 6);
            rootOff += fileEntryLen;

            printf("%s\n", strFilename);
            FILE *fOut = fopen(strFilename, "wb");
            if (fOut) {
                fwrite(dec + off, 1, len, fOut);
                fclose(fOut);
            }
        }
        free(dec);
    }
}