#include <stdio.h>
#include <math.h>

void printAsBinary(unsigned short);
void send(int);
void receive(int);


unsigned char   simulatedInstructions[] =  {0b0110,   // 6
					    0b0000,   // 0
					    0b0011,   // 3
					    0b1111,   // 15
					    0b0001};  // 1
					
unsigned char   simulatedData[] =  {0b00110011,       // 51
				    0b11100000,       // 228
				    0b10101010,       // 170
				    0b00000000,       // 0
				    0b11111111};      // 255

unsigned short  simulatedResults[] =  {0b0000101000010110,  // 161 
				       0b1010000000000000,  // error  code 2
				       0b1101001110010011,  // error code 5
				       0b0000111111101111,  // 254
				       0b0000000111110001}; // 31


int main() {
  unsigned short  result;

  // Send 5 commands and get 5 results
  for (int i=0; i<5; i++) {
    send(i);
    receive(i) ;
  }

  return 0;
}


// Simulate the sending of an instruction with data to the device
void send(int i) {
  unsigned short command = simulatedInstructions[i] + (simulatedData[i] << 4);
  printf("Sending Command: ");
  printAsBinary(command);
}


// Simulate the receiving of a one byte data reply from the device.  An
// error may have occurred, so this is checked for before the data is read.
void receive(int i) {
  unsigned short  result = simulatedResults[i];
  if ((result & 0b1000000000000000) > 0)
    printf("An error has occurred with code: %d\n", (result & (0b111<<12)) >> 12);
  else
    printf("The result data from the device is: %d\n", (result & (255<<4)) >> 4);
}


// Convert an unsigned short to an integer that looks like binary
void printAsBinary(unsigned short n) {
  for (int i=15; i>=0; i--) {
    if ((int)(n/pow(2,i)) > 0) {
      printf("1");
      n = n - pow(2,i);
    }
    else
      printf("0");
  }
  printf("\n");
}