ship: BitFifo

== Ports ===========================================================
data  in:   in

data  in:   cmd.drop
data  in:   cmd.dropInv
data  in:   cmd.takeFillZeros
data  in:   cmd.takeInvFillZeros
data  in:   cmd.takeFillOnes
data  in:   cmd.takeInvFillOnes
data  in:   cmd.takeSignExtend
data  in:   cmd.takeInvSignExtend

data  out:  out

== Constants ========================================================

== TeX ==============================================================

+------+   +--------------+   +-------+
|inData|---|              |---|outData|
+------+   |              |   +-------+
           |              |
+------+   |              |   +-------+
| inOp |---|              |---| outOp |
+------+   +--------------+   +-------+

inOp
+---+
|   |  -- reverse before enqueue
+---+
|   |  -- count := (37-offset-count)
+---+
|   |  -- count (6 bits)
|   |
|   |
|   |
|   |
+---+
|   |  -- offset (6 bits)
|   |
|   |
|   |
|   |
+---+

outOp
+---+
|   |  -- shift until you see a "Z" (2 bits)
+---+
|   |  -- sort the digits
+---+
|   |  -- give me the count
+---+
|   |  -- reverse after dequeue
+---+
|   |  -- count := 37-off-count
+---+
|   |  -- reset the counter before operation
+---+
|   |  -- fill left with (1,0,sign)  (2 bits)
+---+
|   |  -- fill right with (1,0,sign)  (2 bits)
+---+
|   |  -- count (6 bits)
|   |
|   |
|   |
|   |
+---+
|   |  -- offset (6 bits)
|   |
|   |
|   |
|   |
+---+


== Fleeterpreter ====================================================
// Internal storage
private static class BitStorage {
  long[] bits;
  int numbits = 0;
  int start = 0;
  BitStorage(int size) {
    bits = new long[size / 64 + (size % 64 != 0 ? 1 : 0)];
  }
  int size() {
    return numbits;
  }
  boolean hasSpace(int num) {
    return bits.length * 64 - numbits >= num;
  }
  boolean add(long data, int num) {
    if (!hasSpace(num)) return false;
    int entry = ((numbits + start) / 64) % bits.length;
    int off = (numbits + start) % 64;
    int maxadd = 64 - off;
    bits[entry] = (bits[entry] & (-1L >>> maxadd)) | (data << off);
    if (num > maxadd) {
      numbits += maxadd;
      return add(data >>> maxadd, num - maxadd);
    } else {
      numbits += num;
      return true;
    }
  }
  long get(int num) {
    assert size() >= num : "too few bits in storage";
    int entry = start / 64;
    int off = start % 64;
    int max = 64 - off;
    int n = num > max ? max : num;
    long res = (bits[entry] >>> off) & (-1L >>> (64 - n));
    int oldstart = start;
    if (n < num) {
      int n2 = num - n;
      res |= (bits[(entry + 1) % bits.length] & (-1L >>> (64 - n2))) << n;
    }
    start = (start + num) % (64 * bits.length);
    numbits -= num;
    return res;
  }
  int capacity() {
    return 64 * bits.length;
  }
  // Test code for BitStorage
  static void test2(String[] args) {
      int iters = (args.length > 0 ? Integer.parseInt(args[0]) : 10);
      BitStorage bs = new BitStorage(37 * iters);
      Random rand = new Random();
      Vector ins = new Vector();
      Vector ret = new Vector();
      StringBuffer sbi = new StringBuffer();
      StringBuffer sbr = new StringBuffer();
      System.out.println("==== Test #2 ====");
      for (int i = 0; i < iters; i++) {
	  long data = rand.nextLong();
	  int num = rand.nextInt(37);
	  int s = bs.size();
	  bs.add(data, num);
	  assert bs.size() - s == num : "bad size: " + s + " + " + num + " != " + bs.size();
	  ins.add(new Integer(num));
	  add(sbi, data, num);
	  num = rand.nextInt(Math.min(37, bs.size()));
	  s = bs.size();
	  data = bs.get(num);
	  assert s - bs.size() == num : "bad size: " + s + " - " + num + " != " + bs.size();
	  ret.add(new Integer(num));
	  add(sbr, data, num);
      }
      //for (int i = 0; i < iters; i++) {
      while (bs.size() > 0) {
	  int num = Math.min(rand.nextInt(37), bs.size());
	  //int num = Math.min(33, bs.size());
	  int s = bs.size();
	  long data = bs.get(num);
	  assert s - bs.size() == num : "bad size: " + s + " - " + num + " != " + bs.size();
	  ret.add(new Integer(num));
	  add(sbr, data, num);
      }
      System.out.println("inserted:");
      System.out.println(sbi);
      System.out.println("retrieved:");
      System.out.println(sbr);
      System.out.println("insertion sequence:");
      for (int i = 0; i < ins.size(); i++) {
	  System.out.print(" " + ins.get(i));
      }
      System.out.println("\nretrieval sequence:");
      for (int i = 0; i < ret.size(); i++) {
	  System.out.print(" " + ret.get(i));
      }
      System.out.println();
      check(sbi, sbr);
  }
  static void test1(String[] args) {
      int iters = (args.length > 0 ? Integer.parseInt(args[0]) : 10);
      BitStorage bs = new BitStorage(37 * iters);
      Random rand = new Random();
      Vector ins = new Vector();
      Vector ret = new Vector();
      StringBuffer sbi = new StringBuffer();
      StringBuffer sbr = new StringBuffer();
      System.out.println("==== Test #1 ====");
      System.out.println("inserting...");
      for (int i = 0; i < iters; i++) {
	  long data = rand.nextLong();
	  int num = rand.nextInt(37);
	  int s = bs.size();
	  bs.add(data, num);
	  assert bs.size() - s == num : "bad size: " + s + " + " + num + " != " + bs.size();
	  ins.add(new Integer(num));
	  add(sbi, data, num);
	  print(data, num);
      }
      System.out.println("\nretrieving...");
      //for (int i = 0; i < iters; i++) {
      while (bs.size() > 0) {
	  int num = Math.min(rand.nextInt(37), bs.size());
	  //int num = Math.min(33, bs.size());
	  int s = bs.size();
	  long data = bs.get(num);
	  assert s - bs.size() == num : "bad size: " + s + " - " + num + " != " + bs.size();
	  ret.add(new Integer(num));
	  add(sbr, data, num);
	  print(data, num);
      }
      System.out.println("\ninsertion sequence:");
      for (int i = 0; i < ins.size(); i++) {
	  System.out.print(" " + ins.get(i));
      }
      System.out.println("\nretrieval sequence:");
      for (int i = 0; i < ret.size(); i++) {
	  System.out.print(" " + ret.get(i));
      }
      System.out.println();
      check(sbi, sbr);
  }
  static void print(long data, int num) {
      for (int i = 0; i < num; i++) {
	  System.out.print((data >>> i) & 0x1);
      }
  }
  static void add(StringBuffer sb, long data, int num) {
      for (int i = 0; i < num; i++) {
	  sb.append((int) ((data >>> i) & 0x1));
      }
  }
  static void check(StringBuffer sb1, StringBuffer sb2) {
      int len = sb2.length();
      if (len > sb1.length()) {
	  System.out.println("error: retrieval sequence is longer than insertion sequence");
	  len = sb1.length();
      }
      for (int i = 0; i < sb2.length(); i++) {
	  if (sb1.charAt(i) != sb2.charAt(i)) {
	      System.out.println("error: bit at position " + i + " does not match");
	  }
      }
  }
}

// Run BitStorage tests
public static void main(String[] args) {
    BitStorage.test1(args);
    BitStorage.test2(args);
}

// Ship implementation
private Packet selector;
private static final int MAXBITS = 128;
private static final int WORDSIZE = 37;
private BitStorage bits = new BitStorage(MAXBITS);

public void service() {
  if (!box_out.readyForDataFromShip() && !box_in.dataReadyForShip()) return;
  if (box_in.dataReadyForShip() && bits.hasSpace(WORDSIZE)) {
    long data = box_in.removeDataForShip();
    bits.add(data, WORDSIZE);
  }
  if (selector == null && !box_cmd.dataReadyForShip()) return;
  if (selector == null) selector = box_cmd.removePacketForShip();

  String port = selector.destination.getDestinationName();
  long val = selector.value; // check if <= 37?

  if (port.startsWith("takeInv") || port.startsWith("dropInv")) {
    val = 37 - val;    
  }
  if (val < bits.size()) {
    return;
  }

  if (port.startsWith("take")) {
    if (!box_out.readyForDataFromShip()) return;
    long data = bits.get((int) val);
    if (port.endsWith("FillOnes")) {
      data |= (-1L << val);
    } else if (port.endsWith("SignExtend")) {
      data = (data << (64 - val)) >> (64 - val);
    }
    box_out.addDataFromShip(data);
    selector = null;
    return;
  } else {
    bits.get((int) val);
    selector = null;
    return;
  }
}

== FleetSim ==============================================================

== FPGA ==============================================================

== Contributors =========================================================
Amir Kamil <kamil@cs.berkeley.edu>