arduino_cup_if.ino

/**
   Arduino CPU Project
   by: Evan Pratten
*/

/***********************
   Definitions for I/O
 ***********************/

// ROM Write Input
#define IN_WRITE_1 6
#define IN_WRITE_2 7
#define IN_WRITE_3 8
#define IN_WRITE_4 9

// Input Mode Buttons
#define NIBBLE_SELECT 5
#define ACTION_BUTTON 4
#define MODE_SEL A0

bool last_ab = false;

// LED Outputs
#define OUT_DISP_1 10
#define OUT_DISP_2 16
#define OUT_DISP_3 14
#define OUT_DISP_4 15

// Cycle type
// If false, read inputs
// If true, write outputs
bool cycle_type = false;

// System Mode
#define PGRM 1
#define RUN 2

int mode = PGRM;

// Memory
#define MEM_SIZE 512
int system_memory[MEM_SIZE];
int mem_ptr = *system_memory + 28; // Program memory starts at 0001 1011

// Registers
int system_registers[4];

// Datatypes
#define DATTYPE_I8 128    // 1000 0000
#define DATTYPE_I16 64    // 0100 0000
#define DATTYPE_REG 192   // 1100 0000
#define DATTYPE_MEM8 32   // 0010 0000
#define DATTYPE_MEM16 160 // 1010 0000

// Instructions
#define INS_NOP 0   // 0000 0000
#define INS_MOV 1   // 0000 0001
#define INS_ADD 2   // 0000 0010
#define INS_SUB 3   // 0000 0011
#define INS_MUL 4   // 0000 0100
#define INS_DIV 5   // 0000 0101
#define INS_CALL 6  // 0000 0110
#define INS_JMP 7   // 0000 0111
#define INS_CMP 8   // 0000 1000
#define INS_CMPL 9  // 0000 1001
#define INS_CMPG 10 // 0000 1010
#define INS_NCMP 11 // 0000 1011

// System calls
#define SYSCALL_HALT 128 // 1000 0000
#define SYSCALL_DISP 64  // 0100 0000

void setup() {

  // Init I/O
  pinMode(IN_WRITE_1, INPUT);
  pinMode(IN_WRITE_2, INPUT);
  pinMode(IN_WRITE_3, INPUT);
  pinMode(IN_WRITE_4, INPUT);

  pinMode(NIBBLE_SELECT, INPUT);
  pinMode(ACTION_BUTTON, INPUT);
  pinMode(MODE_SEL, INPUT);

  pinMode(OUT_DISP_1, OUTPUT);
  pinMode(OUT_DISP_2, OUTPUT);
  pinMode(OUT_DISP_3, OUTPUT);
  pinMode(OUT_DISP_4, OUTPUT);


  Serial.begin(9600);
}

void handleInput() {

  // Read mode type
  if(digitalRead(MODE_SEL)){
    mode = PGRM;
  }else{
    mode = RUN;
  }

  // Read inputs to memory
  if (digitalRead(NIBBLE_SELECT)) {
    system_memory[1] &= 15;

    // Bit 1
    if ((digitalRead(IN_WRITE_1) != (system_memory[1] & 16)) && digitalRead(IN_WRITE_1)) {
      if (system_memory[0] & 16) {
        system_memory[0] &= 239;
      } else {
        system_memory[0] |= 16;
      }
    }
    system_memory[1] |= ((digitalRead(IN_WRITE_1)) ? 16 : 0);

    // Bit 2
    if ((digitalRead(IN_WRITE_2) != (system_memory[1] & 32)) && digitalRead(IN_WRITE_2)) {
      if (system_memory[0] & 32) {
        system_memory[0] &= 223;
      } else {
        system_memory[0] |= 32;
      }
    }
    system_memory[1] |= ((digitalRead(IN_WRITE_2)) ? 32 : 0);

    // Bit 3
    if ((digitalRead(IN_WRITE_3) != (system_memory[1] & 64)) && digitalRead(IN_WRITE_3)) {
      if (system_memory[0] & 64) {
        system_memory[0] &= 191;
      } else {
        system_memory[0] |= 64;
      }
    }
    system_memory[1] |= ((digitalRead(IN_WRITE_3)) ? 64 : 0);
    
    // Bit 4
    if ((digitalRead(IN_WRITE_4) != (system_memory[1] & 128)) && digitalRead(IN_WRITE_4)) {
      if (system_memory[0] & 128) {
        system_memory[0] &= 127;
      } else {
        system_memory[0] |= 128;
      }
    }
    system_memory[1] |= ((digitalRead(IN_WRITE_4)) ? 128 : 0);
    
  } else {
    system_memory[1] &= 240;

    // Bit 1
    if ((digitalRead(IN_WRITE_1) != (system_memory[1] & 1)) && digitalRead(IN_WRITE_1)) {
      if (system_memory[0] & 1) {
        system_memory[0] &= 254;
      } else {
        system_memory[0] |= 1;
      }
    }
    system_memory[1] |= ((digitalRead(IN_WRITE_1)) ? 1 : 0);

    // Bit 2
    if ((digitalRead(IN_WRITE_2) != (system_memory[1] & 2)) && digitalRead(IN_WRITE_2)) {
      if (system_memory[0] & 2) {
        system_memory[0] &= 253;
      } else {
        system_memory[0] |= 2;
      }
    }
    system_memory[1] |= ((digitalRead(IN_WRITE_2)) ? 2 : 0);

    // Bit 3
    if ((digitalRead(IN_WRITE_3) != (system_memory[1] & 4)) && digitalRead(IN_WRITE_3)) {
      if (system_memory[0] & 4) {
        system_memory[0] &= 251;
      } else {
        system_memory[0] |= 4;
      }
    }
    system_memory[1] |= ((digitalRead(IN_WRITE_3)) ? 4 : 0);
    
    // Bit 4
    if ((digitalRead(IN_WRITE_4) != (system_memory[1] & 8)) && digitalRead(IN_WRITE_4)) {
      if (system_memory[0] & 8) {
        system_memory[0] &= 247;
      } else {
        system_memory[0] |= 8;
      }
    }
    system_memory[1] |= ((digitalRead(IN_WRITE_4)) ? 8 : 0);
  }

  
  if (mode == PGRM) {
    // Copy the inputs to the display if we are writing to ROM
    system_memory[2] = system_memory[0];

    // Copy inputs to current mem addr
    system_memory[mem_ptr] = system_memory[0];

    // Handle mem addr incr and decr requests
    if(digitalRead(ACTION_BUTTON) != last_ab && digitalRead(ACTION_BUTTON)){
      if(digitalRead(NIBBLE_SELECT)){
        mem_ptr = max(0, mem_ptr - 1);
      }else{
        mem_ptr = min(MEM_SIZE - 1, mem_ptr + 1);
      }
      system_memory[0] = system_memory[mem_ptr];
      system_memory[1] = 0;
    }

    last_ab = digitalRead(ACTION_BUTTON);
  }

  Serial.print(mem_ptr, BIN);
  Serial.print(" ");
  Serial.print(system_memory[mem_ptr], BIN);
  Serial.print("\n");

}

void handleOutput() {

  // Read display from memory
  int disp = 0;
  if(mode == PGRM){
    disp = system_memory[mem_ptr];
  }else{
    disp = system_memory[2];
  }

  // Shift outputs if the shift button is held
  if (digitalRead(NIBBLE_SELECT)) {

    // Write status to each LED
    digitalWrite(OUT_DISP_1, disp & 16);
    digitalWrite(OUT_DISP_2, disp & 32);
    digitalWrite(OUT_DISP_3, disp & 64);
    digitalWrite(OUT_DISP_4, disp & 128);
  } else {

    // Write status to each LED
    digitalWrite(OUT_DISP_1, disp & 1);
    digitalWrite(OUT_DISP_2, disp & 2);
    digitalWrite(OUT_DISP_3, disp & 4);
    digitalWrite(OUT_DISP_4, disp & 8);
  }

}

void handleLogic() {

}

void loop() {

  // Handle read vs write
  if (cycle_type) {
    handleInput();
  } else {
    handleOutput();
  }

  // Handle logic
  handleLogic();

  cycle_type = !cycle_type;

}