public ProgramChunkJumpUnconditional(ProgramChunkJumpTarget myTarget)
{
Target = myTarget;
}
public void AddOrphanJumpTarget(ProgramChunkJumpTarget target)
{
ProgramOrphanJumpTargets.AddLast(((IProgramChunk)target));
}
public void RemoveOrphanJumpTarget(ProgramChunkJumpTarget target)
{
ProgramOrphanJumpTargets.Remove(target);
}
/// <summary>
/// Translates a line of MIPS assembly into the intermediate format and returns
/// the result.
/// </summary>
/// <param name="assembly">MIPS assembly.</param>
/// <param name="parentBlock">ProgramBlock containing previously translated code
/// and associated information</param>
/// <returns>Translated chunk.</returns>
public IProgramChunk TranslateLine(string assembly, ProgramBlock parentBlock)
{
IProgramChunk translatedChunk = null;
//***LABELS***
if (assembly.Contains(":"))
{
string labelName = assembly.Substring(0, assembly.IndexOf(":"));
//label does not exist as an orphan
if(parentBlock.GetOrphanJumpTargetByLabel(labelName) == null)
translatedChunk = new ProgramChunkJumpTarget(labelName);
//label does exist as an orphan.
else
{
translatedChunk = parentBlock.GetOrphanJumpTargetByLabel(labelName);
parentBlock.RemoveOrphanJumpTarget(parentBlock.GetOrphanJumpTargetByLabel(labelName));
}
}
//**KEYWORDS**
else
{
string lineKeyword = assembly.Split(' ')[0];
string[] lineParameters = assembly.Substring(assembly.IndexOf(' ') + 1).Split(' ');
switch (lineKeyword)
{
#region J - Unconditional Jump
case "j":
{
ProgramChunkJumpTarget target = parentBlock.GetJumpTargetByLabel(lineParameters[0]);
//label does not exist but should be defined later. create an orphan placeholder.
if (target == null)
{
target = new ProgramChunkJumpTarget(lineParameters[0]);
parentBlock.AddOrphanJumpTarget(target);
}
translatedChunk = new ProgramChunkJumpUnconditional(target);
}
break;
#endregion
#region Form: (command) product, multiplicand, multiplier
case "addi":
case "add":
case "sllv"://SLL - Shift Left Logical (variable)
case "sll": //SLL - Shift Left Logical (constant)
case "sub":
case "subi":
//Form: (command) product, multiplicand, multiplier
//see below (or above i guess) to see acceptable commands
//Addition: 'add', and 'addi' (default)
Operand commandOperand = Operand.ADDITION;
//Multiplication: 'sll', and 'sllv'
if(lineKeyword.Equals("sll") || lineKeyword.Equals("sllv"))
commandOperand = Operand.MULTIPLICATION;
//Subtraction: 'sub', and 'subi'
if(lineKeyword.Equals("sub") || lineKeyword.Equals("subi"))
commandOperand = Operand.SUBTRACTION;
BlockVariable termAssignee; //must be variable
ProgramChunkExpressionTerm termMultiplicand;//constant or variable? I think the doc only support var's
ProgramChunkExpressionTerm termMultiplier; //constant or variable
#region 1) find assignee
if (IsVariable(lineParameters[0]))
{
ProcessVariable(ref lineParameters[0]);
BlockVariable variable = parentBlock.GetVariableByNameForced(lineParameters[0]);
termAssignee = variable;
}
else
throw new Exception("FrontendMIPS - Detected attempt to assign expression to constant.");
#endregion
#region 2) find multiplicand
if (IsVariable(lineParameters[1]))
{
ProcessVariable(ref lineParameters[1]);
BlockVariable variable = parentBlock.GetVariableByNameForced(lineParameters[1]);
termMultiplicand = variable;
}
else //The first (real) term is a constant
{
//CHECKME: attempt to parse hex numbers, does it work this way?
int term = int.Parse(lineParameters[1], System.Globalization.NumberStyles.HexNumber);
termMultiplicand = new BlockConstant(term);
}
#endregion
#region 3) find multiplier
if (IsVariable(lineParameters[2]))
{
ProcessVariable(ref lineParameters[2]);
BlockVariable variable = parentBlock.GetVariableByNameForced(lineParameters[2]);
termMultiplier = variable;
}
else//constant
{
//TODO: support hex numbers
if(lineParameters[2].Contains("x"))
throw new Exception("FrontendMIPS - Cannot parse hexidecimal numbers.");
int term = int.Parse(lineParameters[2]);
//deal with bit shifts
if (lineKeyword.Equals("sll"))
term *= 2;
else if (lineKeyword.Equals("sllv"))
throw new Exception("FrontendMIPS - Cannot bit shift by variable without subexpression support.");
termMultiplier = new BlockConstant(term);
}
#endregion
ProgramChunkExpression expression = new ProgramChunkExpression(termMultiplicand, commandOperand, termMultiplier);
translatedChunk = new ProgramChunkAssignment(termAssignee, expression);
break;
#endregion
#region Branchs (BNE, BEQ)
//Form: if (var equality var) goto label.
//e.g. "beq $a1 0 finish"
case "bne":
case "beq":
{
Equality equality;
ProgramChunkExpressionTerm first;
ProgramChunkExpressionTerm second;
ProgramChunkJumpTarget target;
#region 1) determine equality
if (lineKeyword.Equals("bne"))
equality = Equality.NOT_EQUAL;
else if (lineKeyword.Equals("beq"))
equality = Equality.EQUAL;
else
throw new Exception("FrontendMIPS - Unimplemented equality found.");
#endregion
#region 2) find first item to evaluate
if (IsVariable(lineParameters[0]))
{
ProcessVariable(ref lineParameters[0]);
first = parentBlock.GetVariableByNameForced(lineParameters[0]);
}
else //constant
{
//TODO: support hex numbers
if (lineParameters[0].Contains("x"))
throw new Exception("FrontendMIPS - Cannot parse hexidecimal numbers.");
first = new BlockConstant(int.Parse(lineParameters[0]));
}
#endregion
#region 3) find second item to evaluate
if (IsVariable(lineParameters[1]))
{
ProcessVariable(ref lineParameters[1]);
second = parentBlock.GetVariableByNameForced(lineParameters[1]);
}
else //constant
{
//TODO: support hex numbers
if (lineParameters[1].Contains("x"))
throw new Exception("FrontendMIPS - Cannot parse hexidecimal numbers.");
second = new BlockConstant(int.Parse(lineParameters[1]));
}
#endregion
#region 4) generate jump for true
target = parentBlock.GetJumpTargetByLabel(lineParameters[2]);
//label does not exist but should be defined later. create an orphan placeholder.
if (target == null)
{
target = new ProgramChunkJumpTarget(lineParameters[2]);
parentBlock.AddOrphanJumpTarget(target);
}
#endregion
translatedChunk = new ProgramChunkBranch(equality, first, new ProgramChunkJumpUnconditional(target), second, new ProgramChunkNoOperation());
}
break;
#endregion
}
}
if (translatedChunk == null)
{
translatedChunk = new ProgramChunkNoOperation();
UtilDebugConsole.AddException(new Exception("FrontendMIPS - Unidentified assembly encountered during translation."));
}
return translatedChunk;
}
