#include "decrypt.h"
#include "utils/decryptUtilities.h"

struct DECRYPTION_DATA {
  uint32_t key0;
  uint32_t key1;
  uint32_t key2;
};

struct DECRYPTION_DATA decryptor;

void initDecryptor(uint32_t key0, uint32_t key1, uint32_t key2) {
  decryptor.key0 = key0;
  decryptor.key1 = key1;
  decryptor.key2 = key2;
}

/** Decrypts the given input in-place. The input buffer will be modified. */
void decrypt(uint8_t* chunk, unsigned long length) {
  for (unsigned long i = 0; i < length; i += 1) {
    uint8_t curChar = chunk[i];
    curChar = curChar ^ decryptByte((uint16_t)((uint16_t)(decryptor.key2 & (uint16_t)0xFFFF) | (uint16_t)2));
    updateKeys(&(decryptor.key0), &(decryptor.key1), &(decryptor.key2), curChar);
    chunk[i] = curChar;
  }
}