Method GetBaseN

secp256k1/Int.cpp:1017–1053

// ------------------------------------------------

char* Int::GetBaseN(int n,const char *charset) {
  char *ret = (char*) calloc(1,1024);

  Int N(this);
  int offset = 0;
  int isNegative = N.IsNegative();
  if (isNegative) N.Neg();

  // TODO: compute max digit
  unsigned char digits[1024];
  memset(digits, 0, sizeof(digits));

  int digitslen = 1;
  for (int i = 0; i < NB64BLOCK * 8; i++) {
    unsigned int carry = N.GetByte(NB64BLOCK*8 - i - 1);
    for (int j = 0; j < digitslen; j++) {
      carry += (unsigned int)(digits[j]) << 8;
      digits[j] = (unsigned char)(carry % n);
      carry /= n;
    }
    while (carry > 0) {
      digits[digitslen++] = (unsigned char)(carry % n);
      carry /= n;
    }
  }

  // reverse
  if (isNegative)
    ret[offset++] = '-';

  for (int i = 0; i < digitslen; i++)
    ret[offset++] = charset[digits[digitslen - 1 - i]];

  if (offset == 0)
    ret[offset] = '0';
  return ret;
}

// ------------------------------------------------