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TextSegment.java
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TextSegment.java
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import java.util.*;
import java.math.*;
/**
* Class for TextSegment memory
* Holds instructions
*/
public class TextSegment extends Memory {
/**
* Initialized to 2 KB starting at 0x00400000
*/
public TextSegment() {
super(2*1024, 0x00400000);
}
public TextSegment(int size, int start) {
super(size, start);
}
/**
* Throw text segment specific overflow error message
*/
protected void throwOverflowError() {
System.out.println("Your text segment memory is full");
}
/**
* Get starting value
* @return return starting location of memory (byte address)
*/
public int getStart() {
return this.start;
}
/**
* Runs given command from text segment memory
* Increments pc by 4 when appropriate
* @param mips Give mips object so can access other memory locations and registers
* @param printCmd boolean determining whether or not to print the command that was executed
* @return int, -1 when program is done, 0 otherwise
*/
public int run(MIPSEmulator mips, boolean printCmd) {
int loc = mips.reg.pc;
mips.reg.pc += 4;
String cmd = "";
// Figure out what type it is
int opcode = getBits(loc, 26, 31, false);
int rs, rt, rd, immed, shamt, func, addr, immedU, addrU;
if(opcode == 0) { //R-Type
rs = getBits(loc, 21, 25, false);
rt = getBits(loc, 16, 20, false);
rd = getBits(loc, 11, 15, false);
shamt = getBits(loc, 6, 10, false);
func = getBits(loc, 0, 5, false);
switch(func) {
case 0: //SLL
cmd = "SLL $"+rd+" = $"+rt+" << " + shamt;
mips.reg.set(rd, mips.reg.get(rt) << shamt);
break;
case 2: //SRL
cmd = "SRL $"+rd+" = $"+rt+" >>> " + shamt;
mips.reg.set(rd, mips.reg.get(rt) >>> shamt);
break;
case 3:
cmd = "SRA $"+rd+" = $"+rt+" >> "+shamt;
mips.reg.set(rd, mips.reg.get(rt) >> shamt);
break;
case 8: //JR
cmd = "JR $"+ rs;
if(mips.reg.get(rs) == -1){
return -1;
}
mips.reg.pc = mips.reg.get(rs);
break;
case 12:
cmd="syscall "+mips.reg.get(2);
if(mips.reg.get(2) == 1) {
System.out.print(mips.reg.get(4)); //get corrector register
} else if(mips.reg.get(2) == 4) { //print string
boolean stringIncomplete = true;
int l = mips.reg.get(4);
while(stringIncomplete) {
int x = mips.getMemoryByte(l, 0, false);
if(x == 0) {
stringIncomplete = false;
break;
}
System.out.print((char)(x));
l++;
}
} else if(mips.reg.get(2) == 5) {
String temp = MIPSEmulator.getUserInput("");
int t = 0;
try {
t =Integer.parseInt(temp);
mips.reg.set(2, t);
} catch (NumberFormatException e) {
System.out.println("Invalid input");
}
} else if(mips.reg.get(2) == 8) {
String temp = MIPSEmulator.getUserInput("");
int i = 0;
int sloc = mips.reg.get(4);
while(i < temp.length() && i < mips.reg.get(5)) {
int val = (int)temp.charAt(i);
mips.setMemoryByte(sloc+i, 0, val);
i++;
}
} else if(mips.reg.get(2) == 10) {
return -1;
}
break;
case 16:
cmd = "MFHI $"+rd+" = $HI";
mips.reg.set(rd, mips.reg.get("HI"));
break;
case 18:
cmd = "MFLO $"+rd+" = $LO";
mips.reg.set(rd, mips.reg.get("LO"));
break;
case 24:
cmd = "MULT $LO =$"+rs+" x $"+rt;
long l1 = mips.reg.get(rs);
long l2 = mips.reg.get(rt);
long m = l1 * l2;
int lo = (int)((m << 32) >>> 32);
int hi = (int)(m >>> 32);
mips.reg.set("LO", lo);
mips.reg.set("HI", hi);
break;
case 25:
cmd = "MULTU $LO =$"+rs+" x $"+rt;
mips.reg.set("LO", mips.reg.get(rs) * mips.reg.get(rt));
break;
case 32: //add with overflow
cmd="ADD $"+rd+"=$"+rs+" + $"+rt;
mips.reg.set(rd, mips.reg.get(rs) + mips.reg.get(rt));
break;
case 33:
cmd="ADDU $"+rd+"=$"+rs+" + $"+rt;
mips.reg.set(rd, mips.reg.get(rs) + mips.reg.get(rt));
break;
case 34:
cmd="SUB $"+rd+"=$"+rs+" - $"+rt;
mips.reg.set(rd, mips.reg.get(rs) - mips.reg.get(rt));
break;
case 35:
cmd="SUBU $"+rd+"=$"+rs+" - $"+rt;
mips.reg.set(rd, mips.reg.get(rs) - mips.reg.get(rt));
break;
case 36:
cmd="AND $"+rd+"=$"+rs+" & $"+rt;
mips.reg.set(rd, mips.reg.get(rs) & mips.reg.get(rt));
break;
case 37:
cmd="OR $"+rd+"=$"+rs+" | $"+rt;
mips.reg.set(rd, mips.reg.get(rs) | mips.reg.get(rt));
break;
case 38:
cmd="XOR $"+rd+"=$"+rs+" ^ $"+rt;
mips.reg.set(rd, mips.reg.get(rs) ^ mips.reg.get(rt));
break;
case 39:
cmd = "NOR";
break;
case 42:
//if $s < $t $d = 1; advance_pc (4); else $d = 0;
cmd = "SLT if $"+rs+"<"+rt+" ? $"+rd+" = 1 : $"+rd+" = 0";
if (mips.reg.get(rs) < mips.reg.get(rt))
mips.reg.set(rd, 1);
else
mips.reg.set(rd, 0);
break;
case 43:
cmd = "SLTU if $"+rs+"<"+rt+" ? $"+rd+" = 1 : $"+rd+" = 0";
long val1 = ((long)(mips.reg.get(rs)) << 32) >>> 32;
long val2 = ((long)(mips.reg.get(rt)) << 32) >>> 32;
if (val1 < val2)
mips.reg.set(rd, 1);
else
mips.reg.set(rd, 0);
break;
default:
cmd = "OTHER R INSTRUCTION -- " + opcode + " -- " + func;
break;
}
} else { //I-Type and J-Type have to be considered together
rs = getBits(loc, 21, 25, false);
rt = getBits(loc, 16, 20, false); // > I-Type
immed = getBits(loc, 0, 15);
immedU = getBits(loc, 0, 15, false);
addr = getBits(loc, 0, 25); // J-Type
addrU = getBits(loc, 0, 25, false);
switch(opcode) {
case 1:
if(rt == 1) {
cmd = "BGEZ $"+rs+", "+immed;
if(mips.reg.get(rs) >= 0) {
mips.reg.pc -= 4;
mips.reg.pc += (immed << 2);
}
} else if (rt == 0) {
cmd = "BLTZ $"+rs+", "+immed;
if(mips.reg.get(rs) < 0) {
mips.reg.pc -= 4;
mips.reg.pc += (immed << 2);
}
}
break;
case 2:
cmd = "J "+addrU;
mips.reg.pc -= 4;
mips.reg.pc = (mips.reg.pc & 0xF0000000) | (addrU << 2);
break;
case 3:
cmd = "JAL " + addrU;
mips.reg.set(31, mips.reg.pc);
mips.reg.pc = (mips.reg.pc & 0xF0000000) | (addrU << 2);
break;
case 4:
cmd = "BEQ $"+rs+", $"+rt+", "+immed;
if(mips.reg.get(rs) == mips.reg.get(rt)) {
mips.reg.pc -= 4;
mips.reg.pc += (immed << 2);
}
break;
case 5:
cmd = "BNE $"+rs+", $"+rt+", "+immed;
if(mips.reg.get(rs) != mips.reg.get(rt)) {
mips.reg.pc -= 4;
mips.reg.pc += (immed << 2);
}
break;
case 6:
cmd = "BLEZ $"+rs+", "+immed;
if(mips.reg.get(rs) <= 0) {
mips.reg.pc -= 4;
mips.reg.pc += (immed << 2);
}
break;
case 7:
cmd = "BGTZ $"+rs+", "+immed;
if(mips.reg.get(rs) > 0) {
mips.reg.pc -= 4;
mips.reg.pc += (immed << 2);
}
break;
case 8:
cmd = "ADDI $"+rt+"=$"+rs+" + "+immed;
mips.reg.set(rt, mips.reg.get(rs) + immed);
break;
case 9:;
cmd = "ADDIU $"+rt+"=$"+rs+" + "+immed;
mips.reg.set(rt, mips.reg.get(rs) + immed);
break;
case 10:
cmd = "SLTI if $"+rs+"<"+immed+" ? $"+rt+" = 1 : $"+rt+" = 0";
if (mips.reg.get(rs) < immed)
mips.reg.set(rt, 1);
else
mips.reg.set(rt, 0);
break;
case 11:
cmd = "SLTIU if $"+rs+"<"+immed+" ? $"+rt+" = 1 : $"+rt+" = 0";
long val1 = ((long)(mips.reg.get(rs)) << 32) >>> 32;
long val2 = ((long)(immed) << 32) >>> 32;
if (val1 < val2)
mips.reg.set(rt, 1);
else
mips.reg.set(rt, 0);
break;
case 12:
cmd = "ANDI";
break;
case 13:
cmd = "ORI $"+rt+"=$"+rs+" | "+immedU;
mips.reg.set(rt, mips.reg.get(rs) | immedU);
break;
case 0x0F:
cmd = "LUI $" + rt + ", " + immedU;
mips.reg.set(rt, immedU << 16);
break;
case 0x20:
cmd = "LB $"+rt+" = MEM[$"+rs+" + "+immed+"]";
mips.reg.set(rt, mips.getMemoryByte(mips.reg.get(rs), immed, true));
break;
case 0x23:
cmd = "LW $"+ rt+"= MEM[$"+rs+" + "+immed+"]";
mips.reg.set(rt, mips.getFromMemory(mips.reg.get(rs), immed));
break;
case 0x24:
cmd = "LBU $"+rt+" = MEM[$"+rs+" + "+immed+"]";
mips.reg.set(rt, mips.getMemoryByte(mips.reg.get(rs), immed, false));
break;
case 0x28:
cmd = "SB MEM[ $" +rs+" + "+immed+"] = $"+rt;
mips.setMemoryByte(mips.reg.get(rs), immed, mips.reg.get(rt));
break;
case 0x2B:
cmd = "SW MEM[ $" +rs+" + "+immed+"] = $"+rt;
mips.setMemory(mips.reg.get(rs), immed, mips.reg.get(rt));
break;
default:
cmd = "OTHER I OR J: " + opcode + " -- " + Integer.toBinaryString(opcode) + " -- " + MIPSEmulator.formatHex(opcode);
break;
}
}
//cmd += " -- 0x" + MIPSEmulator.formatHex(this.get(loc)); //for debugging
if(!cmd.equals("") && printCmd) System.out.println(cmd);
return 0;
}
}