/* Copyright (c) 1997 Andrew W. Appel.  Licensed software: see LICENSE file */
package Mips;
import Temp.Temp;
import Temp.TempList;
import Temp.Label;
import java.util.*;

class InFrame extends Frame.Access {
  int offset;
  InFrame(int o) {offset=o;}
  public Tree.Exp exp(Tree.Exp framePtr) {
    return new Tree.MEM(new Tree.BINOP(Tree.BINOP.PLUS,framePtr,new Tree.CONST(offset)));
  }
}

class InReg extends Frame.Access {
  Temp temp;
  InReg(Temp t) {temp=t;}
  public Tree.Exp exp(Tree.Exp framePtr) {
    return new Tree.TEMP(temp);
  }
}

public class MipsFrame extends Frame.Frame {

   static java.util.Dictionary tempTab = new java.util.Hashtable();
   static TempList regs = null;

   static Temp enterTemp(String reg) {
	Temp t = new Temp();
	regs = new TempList(t, regs);
	tempTab.put(t, reg);
	return t;
   }

   public String tempMap(Temp t) {return (String)tempTab.get(t);}

   public TempList registers() {return regs;}

   final static Temp FPx = new Temp();
   final static Temp ZEROx = enterTemp("$0");
   final static Temp SPx = enterTemp("$sp");
   final static Temp RAx = enterTemp("$31");

   static {tempTab.put(FPx,"$fp");}

   final static TempList 
	callerSaves=withtemp("$2 $4 $5 $6 $7 $8 $9 $10 $11 $12 $13 $14 $15 $24 $25"),
	calleeSaves=withtemp("$16 $17 $18 $19 $20 $21 $22 $23 $30"),
	calleeSavesRA = new TempList(RAx, calleeSaves);

   

   final static Temp RVx = callerSaves.head;

   final static int numArgRegs = 5;

   private static TempList withtemp(String s) {
	 java.util.StringTokenizer st = new java.util.StringTokenizer(s);
	 TempList p = new TempList(ZEROx,null);
	 TempList head=p;
         while (st.hasMoreTokens()) {
                p.tail = new TempList(enterTemp(st.nextToken()),null);
		p=p.tail;
         }
	 return head.tail;
   }

   int nFormals;
   int locals;

   Tree.Stm mover = new Tree.EXP(new Tree.CONST(0));

   private Frame.AccessList params(int i, TempList argregs, 
				   Util.BoolList escapes) {
     if (escapes==null) return null;
     else if (i < numArgRegs) {
        Frame.Access formal;
        Tree.Exp actual = new Tree.TEMP(argregs.head);
	if (escapes.head) 
	     formal= new InFrame(i*wordSize());
	else formal= new InReg(new Temp());
        mover = new Tree.SEQ(mover,
	                new Tree.MOVE(formal.exp(new Tree.TEMP(FP())),actual));
        return new Frame.AccessList(formal, params(i+1,argregs.tail,escapes.tail));
     } else
	return new Frame.AccessList(new InFrame(i*wordSize()), 
				params(i+1,null,escapes.tail));
   }

   private MipsFrame(Label nm, Util.BoolList fmls) {
	formals=params(0,callerSaves,fmls);
        name=nm;
	locals=0;
   }

   public MipsFrame() { this(new Label("<bogus>"), null);} 

   public Temp RV() 		    {return RVx;}
   public Temp FP()		    {return FPx;}
   public int wordSize() 	    {return 4;}

   public Tree.Exp externalCall(String func, Tree.ExpList args) {
	return new Tree.CALL(new Tree.NAME(new Label(func)),
			     new Tree.ExpList(new Tree.CONST(0),args));
   }

   

   public Frame.Frame newFrame(Label name, Util.BoolList formals) {
	return new MipsFrame(name,formals);
   }

   public Frame.Access allocLocal(boolean escape) {
	if (escape) 
	     return new InFrame(-wordSize()*(++locals));
	else return new InReg(new Temp());
   }

   public String string(Label label, String value) {
	StringBuffer b = new StringBuffer();
	int i; char c;
        b.append(".data\n");
	b.append(label.toString());
        b.append(":\t.word\t");
	b.append(String.valueOf(value.length()));
	b.append("\n\t.ascii\t\"");
	for(i=0; i<value.length(); i++)
	  switch(c=value.charAt(i)) {
	    case '\n': b.append("\\n"); break;
	    case '\t': b.append("\\t"); break;
	    case 0: b.append("\\0"); break;
	    case '\"': b.append("\\\""); break;
	    case '\'': b.append("\\\'"); break;
	    case '\\': b.append("\\\\"); break;
	    default: 
		if (c>= ' ' && c<127) b.append(c);
		else {
		   b.append('\\');
		   b.append('0' + c>>6);		
	   b.append('0' + (c>>3)&8);	
		   b.append('0' + c&8);	
		}
	}
	b.append("\"\n\t.align\t2\n");
	return b.toString();
   }
			
   final static boolean hasSpillPhase = true;
/*
   public Tree.Stm procEntryExit1(Tree.Stm body) {
      Tree.Stm saveStm=new Tree.EXP(new Tree.CONST(0)),
	    restoreStm=new Tree.EXP(new Tree.CONST(0));

        for(TempList r = calleeSavesRA; r!=null; r=r.tail) {
	    Frame.Access saveLoc = allocLocal(!hasSpillPhase);
	    saveStm=new Tree.SEQ(saveStm,new Tree.MOVE(saveLoc.exp(new Tree.TEMP(FP())),
					       new Tree.TEMP(r.head)));
	    restoreStm=new Tree.SEQ(restoreStm,new Tree.MOVE(new Tree.TEMP(r.head),
					saveLoc.exp(new Tree.TEMP(FP()))));
	}
	return new Tree.SEQ(mover,new Tree.SEQ(saveStm,new Tree.SEQ(body,
			restoreStm))); 
   }
*/

   public Vector procEntryExit1(Tree.Stm body) {
      Vector result=new Vector();

      Tree.Stm saveStm=new Tree.EXP(new Tree.CONST(0)),
	    restoreStm=new Tree.EXP(new Tree.CONST(0));

        for(TempList r = calleeSavesRA; r!=null; r=r.tail) {
	    Frame.Access saveLoc = allocLocal(!hasSpillPhase);
	    saveStm=new Tree.SEQ(saveStm,new Tree.MOVE(saveLoc.exp(new Tree.TEMP(FP())),
					       new Tree.TEMP(r.head)));
	    restoreStm=new Tree.SEQ(restoreStm,new Tree.MOVE(new Tree.TEMP(r.head),
					saveLoc.exp(new Tree.TEMP(FP()))));
	}

      saveStm=new Tree.SEQ(mover, saveStm);
      
      result.addElement(saveStm);
      result.addElement(body);
      result.addElement(restoreStm);

      return result; 
   }

   static TempList returnSink =
	new TempList(ZEROx, new TempList(RAx, new TempList(SPx, calleeSaves)));

   static Assem.InstrList append(Assem.InstrList a, Assem.InstrList b) {
	Assem.InstrList p;
	if (a==null) 
		return b;
	else {
	   for(p=a; p.tail!=null; p=p.tail) ;
	   p.tail=b;
	   return a;
	}
   }

   public Assem.InstrList procEntryExit2(Assem.InstrList body) {
	return append(body,
	     new Assem.InstrList(new Assem.OPER("", null, returnSink),null));
   }

   public Frame.Proc procEntryExit3(Assem.InstrList body) {
	int maxOutgoingActuals = 8;  /* should be calculated! */
	int framesize = 4 * (maxOutgoingActuals + locals);
	String framename = name.toString() + "_framesize";
	String maxframename = name.toString() + "_framesize_max";
/*	String prolog = 
		 "\n\t.globl\t" + name.toString() + "\n\t.ent\t"
		 + name.toString() + "\n\t" + framename + "="
		 + String.valueOf(framesize) + "\n\t.frame\t$sp," 
		 + framename + ",$31\n" + name.toString() 
		 + ":\n\taddiu\t$sp,$sp,-" + framename + "\n";
*/
	String prolog = 
		 "\n.text\n\t.globl\t" + name.toString() + "\n\t.ent\t"
		 + name.toString() + "\n\t" + framename + "="
		 + String.valueOf(framesize) + "\n\t" + 
		 maxframename + "=" + "-" + String.valueOf(framesize) 
		 +"\n\t.frame\t$sp," 
		 + framename + ",$31\n" + name.toString() 
		 + ":\n\taddiu\t$sp,$sp," + maxframename + "\n";
        String epilog = 
		"\taddiu\t$sp,$sp," + framename + "\n\tj\t$31\n\t.end\t"
		+ name.toString() +"\n";
	return new Frame.Proc(prolog,body, epilog);
   }

   public Assem.InstrList codegen(Tree.Stm stm) {
      return (new Codegen(this)).codegen(stm);
   }

}