// See RAM chip pinout here: https://www.digchip.com/datasheets/parts/datasheet/922/MK4116-pdf.php

const PinName kAddressPins[] = {
  PA_7,
  PC_7,
  PB_6,
  PB_10,
  PA_8,
  PA_9,
  PB_4,
};

const PinName kRasPin = PA_6;
const PinName kWritePin = PB_9;
const PinName kDinPin = PB_8;
const PinName kDoutPin = PA_10;
const PinName kCasPin = PB_3;

void Timer1Isr();

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
  Serial.begin(115200);

  for (int i = 0; i < 7; i++) {
    pinMode(pinNametoDigitalPin(kAddressPins[i]), OUTPUT);
  }

  pinMode(pinNametoDigitalPin(kRasPin), OUTPUT);
  pinMode(pinNametoDigitalPin(kCasPin), OUTPUT);
  pinMode(pinNametoDigitalPin(kWritePin), OUTPUT);
  pinMode(pinNametoDigitalPin(kDoutPin), INPUT);
  pinMode(pinNametoDigitalPin(kDinPin), OUTPUT);

  digitalWrite(pinNametoDigitalPin(kRasPin), HIGH);
  digitalWrite(pinNametoDigitalPin(kCasPin), HIGH);
  digitalWrite(pinNametoDigitalPin(kWritePin), HIGH);

  // Instantiate HardwareTimer object. Thanks to 'new' instanciation, HardwareTimer is not destructed when setup() function is finished.
  HardwareTimer *MyTim = new HardwareTimer(TIM1);

  MyTim->setOverflow(1400, MICROSEC_FORMAT);
  MyTim->attachInterrupt(Timer1Isr);
  MyTim->resume();
}

#define LV(x) ((x) ? HIGH : LOW)

void writeAddress(int address) {
  for (int i = 0; i < 7; i++) {
    digitalWriteFast(kAddressPins[i], LV(address & (1 << i)));
  }
}

int read(int address) {
  int row = address >> 7;
  int col = address & 0x7f;

  noInterrupts();

  writeAddress(row);
  digitalWriteFast(kRasPin, LOW);
  writeAddress(col);
  digitalWriteFast(kCasPin, LOW);
  delayMicroseconds(1);  // tCAS ish
  int out = digitalReadFast(kDoutPin);
  
  digitalWriteFast(kCasPin, HIGH);
  digitalWriteFast(kRasPin, HIGH);

  interrupts();

  return out;
}

void write(int address, int data) {
  int row = address >> 7;
  int col = address & 0x7f;

  noInterrupts();

  writeAddress(row);
  digitalWriteFast(kRasPin, LOW);
  digitalWriteFast(kWritePin, LOW);
  digitalWriteFast(kDinPin, LV(data));
  writeAddress(col);
  digitalWriteFast(kCasPin, LOW);

  for (int i = 0; i < 10; i++) asm volatile("");  // extra delay
  digitalWriteFast(kWritePin, HIGH);
  delayMicroseconds(1);  // tCAS ish
  
  digitalWriteFast(kCasPin, HIGH);
  digitalWriteFast(kRasPin, HIGH);

  interrupts();
}

void writepage(int address, const uint8_t data[16]) {
  int row = address >> 7;

  noInterrupts();

  writeAddress(row);
  digitalWriteFast(kRasPin, LOW);
  for (int col = 0; col < 128; col++) {
    int b = data[col >> 3] & (1 << (col % 8));
    digitalWriteFast(kDinPin, LV(b));
    digitalWriteFast(kWritePin, LOW);
    writeAddress(col);
    digitalWriteFast(kCasPin, LOW);

    for (int i = 0; i < 10; i++) asm volatile("");  // extra delay
    digitalWriteFast(kWritePin, HIGH);
    delayMicroseconds(1);  // tCAS ish
    
    digitalWriteFast(kCasPin, HIGH);
  }
  digitalWriteFast(kRasPin, HIGH);

  interrupts();
}

void readpage(int address, uint8_t data[16]) {
  int row = address >> 7;

  noInterrupts();

  writeAddress(row);
  digitalWriteFast(kRasPin, LOW);
  for (int col = 0; col < 128; col++) {
    uint8_t& out = data[col >> 3];

    writeAddress(col);
    digitalWriteFast(kCasPin, LOW);
    delayMicroseconds(1);  // tCAS ish
    int b = digitalReadFast(kDoutPin);
    out >>= 1;
    if (b == HIGH) out |= 0x80;
    digitalWriteFast(kCasPin, HIGH);
  }
  digitalWriteFast(kRasPin, HIGH);

  interrupts(); 
}

int writeread(int address, int value) {
  write(address, value);
  return read(address);
}

void refreshrow(int row) {
  writeAddress(row);
  digitalWriteFast(kRasPin, LOW);
  delayMicroseconds(1);
  digitalWriteFast(kRasPin, HIGH);
}

void refreshall() {
  for (int row = 0; row < 128; row++) {
    refreshrow(row);
  }
}

void Timer1Isr() {
  refreshall();
}

int check01(int address) {
  if (writeread(address, 0) != 0) return -1;
  if (writeread(address, 1) != 1) return -2;

  return 0;
}

int checkrow(int row) {
  int row_address = row << 7;
  for (int i = 0; i < 128; i++) {
    int ret = check01(row_address + i);
    if (ret != 0) {
      Serial.printf("failure at 0x%04x: %d\n", row_address + i, ret);
      return ret;
    }
  }

  return 0;
}

int address = 0x007f;
int led_count = 0;
int led = 0;
char cmd = '\0';

const int kLedInterval = 1000000;

const uint8_t kSampleData[16] = {
  'b', 'l', 'a', 'r', 'g', ',', ' ', 'c',
  'e', 'c', 'i', ' ', 'e', 's', 't', '!',
};

void dump16(int address) {
  address &= 0x3f80;
  uint8_t data[16];
  readpage(address, data);

  Serial.printf("%04x:", address);
  for (int i = 0; i < 16; i++) {
    Serial.printf(" %02x", data[i]);
  }
  Serial.print("  ");
  for (int i = 0; i < 16; i++) {
    if (data[i] < 33 || data[i] > 126) {
      Serial.print(".");
    } else {
      Serial.printf("%c", data[i]);
    }
  }
  Serial.println("");
}

void filltest() {
  uint8_t data[16];
  for (int row = 0; row < 128; row++) {
    snprintf(reinterpret_cast<char*>(data), 16, "testing row %03d", row);
    writepage(row << 7, data);
  }
  for (int row = 0; row < 128; row++) {
    readpage(row << 7, data);
    if (atoi(reinterpret_cast<char*>(&data[12])) != row) {
      Serial.printf("error in row %d\n", row);
      return;
    }
  }
  Serial.println("fill test ok.");
}

void runcmd(char cmd) {
  uint8_t dat[16];

  if (cmd == 'p') {
    writepage(address, kSampleData);
    dump16(address);
  } else if (cmd == '\0') {
    address += 128;
    dump16(address);
  } else if (cmd == '0') {
    address = 0;
    dump16(address);
  } else if (cmd == 'f') {
    filltest();
  } else if (cmd == 't') {
    for (int row = 0; row < 128; row++) {
      Serial.printf("row %d... ", row);
      int ret = checkrow(row);
      if (ret != 0) {
        break;
      }
      Serial.println("ok!");
    }
  }
}

void loop() {
  // put your main code here, to run repeatedly:
  if (led_count > kLedInterval) {
    digitalWrite(LED_BUILTIN, LV(led % 2));
    led += 1;
    led_count = 0;
  }
  led_count += 1;

  if (Serial.available()) {   
    char c = Serial.read();
    if (c == '\n') {
      runcmd(cmd);
      cmd = '\0';
    } else {
      cmd = c;
    }
  }
}