An example of using a GPIO input register to read pin inputs on NodeMCU (esp8266 based) board.

gpio_read_reg.ino

// Our super ultra fast input register
#define GPIO_IN READ_PERI_REG(0x60000318)

#define CHAN0 D1
#define CHAN1 D2
#define CHAN2 D3
#define CHAN3 D4
#define CHAN4 D5

void setup() 
{
  Serial.begin(115200);
  pinMode(D1, INPUT_PULLUP);
  pinMode(D2, INPUT_PULLUP);
  pinMode(D3, INPUT_PULLUP);
  pinMode(D4, INPUT_PULLUP);
  pinMode(D5, INPUT_PULLUP);  
}
 
void loop() 
{
  delay(1000);
  uint16_t pins = GPIO_IN;
  Serial.println(pins, BIN);
}