1 package edu.berkeley.fleet.marina;
2 /* -*- tab-width: 4 -*- */
3 import com.sun.electric.tool.simulation.test.*;
4 import edu.berkeley.fleet.api.Dock;
5 import edu.berkeley.fleet.api.Instruction;
8 * This class encapsulates a "packet" -- a data item in flight plus
9 * its tokenhood and path.
11 * This should be the only class that knows how to turn a packet into
12 * its constituent parts and vice versa.
14 public class MarinaPacket {
16 public static final int PATH_WIDTH = 14;
17 public static final int WORD_WIDTH = 37;
18 public static final int PACKET_WIDTH = PATH_WIDTH+WORD_WIDTH+1;
20 public final BitVector data;
21 public final boolean tokenhood;
22 public final BitVector path;
23 private final boolean is_instruction;
25 public static final BitVector null_path = new BitVector(PATH_WIDTH, "null_path");
26 public static final BitVector null_word = new BitVector(WORD_WIDTH, "null_word");
28 null_path.set(0, PATH_WIDTH, false);
29 null_word.set(0, WORD_WIDTH, false);
32 /** "parse" a token from the raw bits in the north proper stopper */
33 public MarinaPacket(BitVector singleBitVector) {
34 MarinaUtils.expectLength(singleBitVector,PACKET_WIDTH);
35 this.data = new BitVector(WORD_WIDTH, "marina packet data");
36 this.path = new BitVector(PATH_WIDTH, "marina packet path");
37 this.tokenhood = !singleBitVector.get(0);
38 this.is_instruction = false;
39 for(int i=0; i<PATH_WIDTH; i++) path.set(i, singleBitVector.get(i+1));
40 for(int i=0; i<WORD_WIDTH; i++) data.set(i, singleBitVector.get(i+PATH_WIDTH+1));
43 /** manually assemble a packet */
44 public MarinaPacket(BitVector data, boolean tokenhood, BitVector path) {
45 MarinaUtils.expectLength(data, WORD_WIDTH);
46 MarinaUtils.expectLength(path, PATH_WIDTH);
48 this.tokenhood = tokenhood;
50 this.is_instruction = false;
53 /** another constructor which uses an all-zeroes path, for convenience */
54 public MarinaPacket(Instruction inst) {
55 Marina marina = (Marina)inst.dock.getShip().getFleet();
56 BitVector instr = MarinaUtils.berkToSun(marina.encodeInstruction(marina.getOnlyDock(), inst));
57 MarinaUtils.expectLength(instr, MarinaPacket.WORD_WIDTH);
60 // Due to what Ivan calls "geometric inconvenience", incoming
61 // bit 19 is dropped, and all the higher bits are shifted
62 // downward by one position. So we have to compensate for
63 // this by inserting a bogus bit at position #19.
65 BitVector pad = new BitVector(1, "pad");
67 this.data = instr.get(0, 18).cat(pad).cat(instr.get(18,18));
68 this.path = null_path;
69 this.tokenhood = false;
70 this.is_instruction = true;
73 /** convert a packet into a single BitVector, suitable for insertion in the north proper stopper */
74 public BitVector toSingleBitVector() {
75 BitVector bv = new BitVector(PACKET_WIDTH, "marina packet");
76 bv.set(0, !tokenhood);
77 for(int i=0; i<PATH_WIDTH; i++) bv.set(i+1, path.get(i));
78 for(int i=0; i<WORD_WIDTH; i++) bv.set(i+PATH_WIDTH+1, data.get(i));
82 public String toString() {
84 "tokenhood="+(tokenhood ? "token" : "data")
85 + ", path["+PATH_WIDTH+":1]=" + path.bitReverse().getState()
86 + ", data["+WORD_WIDTH+":1]=" +
88 ? (data.get(19,18).bitReverse().getState()+"_"+data.get(0,18).bitReverse().getState())
89 : data.bitReverse().getState());