int ASMParser::cvtNumString2Number(string s)
// Converts a string to an integer. Assumes s is something like "-231" and produces -231
{
if (!isNumberString(s))
{
cerr << "Non-numberic string passed to cvtNumString2Number"
<< endl;
return 0;
}
int k = 1;
int val = 0;
for (int i = s.length()-1; i>0; i--)
{
char c = s.at(i);
val = val + k*((int)(c - '0'));
k = k*10;
}
if (isSign(s.at(0)))
{
if (s.at(0) == '-') val = -1*val;
}
else
{
val = val + k*((int)(s.at(0) - '0'));
}
return val;
}
bool ASMParser::getOperands(Instruction &i, Opcode o,
string *operand, int operand_count)
// Given an Opcode, a string representing the operands, and the number of operands,
// breaks operands apart and stores fields into Instruction.
{
if(operand_count != opcodes.numOperands(o))
return false;
int rs, rt, rd, imm;
imm = 0;
rs = rt = rd = NumRegisters;
int rs_p = opcodes.RSposition(o);
int rt_p = opcodes.RTposition(o);
int rd_p = opcodes.RDposition(o);
int imm_p = opcodes.IMMposition(o);
if(rs_p != -1){
rs = registers.getNum(operand[rs_p]);
if(rs == NumRegisters)
return false;
}
if(rt_p != -1){
rt = registers.getNum(operand[rt_p]);
if(rt == NumRegisters)
return false;
}
if(rd_p != -1){
rd = registers.getNum(operand[rd_p]);
if(rd == NumRegisters)
return false;
}
if(imm_p != -1){
if(isNumberString(operand[imm_p])){ // does it have a numeric immediate field?
imm = cvtNumString2Number(operand[imm_p]);
if(((abs(imm) & 0xFFFF0000)<<1)) // too big a number to fit
return false;
}
else{
if(opcodes.isIMMLabel(o)){ // Can the operand be a label?
// Assign the immediate field an address
imm = myLabelAddress;
myLabelAddress += 4; // increment the label generator
}
else // There is an error
return false;
}
}
i.setValues(o, rs, rt, rd, imm);
return true;
}
bool ExpressionCell::_compute()
{
if (this->computed)
return this->error ? false : true;
if (data[0]!='=')
{
this->error = true;
this->computed = true;
this->data = "#parce_expr_error";
return false;
}
enum {EQUAL='=', PLUS='+', MINUS='-', MULTIPLICATION='*', DIVISION='\\'} signState=EQUAL;
int leftValue = 0;
int rightArgBegin = 1;
for (unsigned int i=1; i<data.size()+1; i++)
{
if ( (i == data.size()-1)
|| isSign(data[i]) )
{
int rightValue = 0;
string rightArg = data.substr(rightArgBegin, i-1);
if (isNumberString(rightArg))
rightValue = atoi(rightArg.c_str());
else if (isCellString(rightArg))
{
pair<int, int> cellCoord = parseCellCoordinate(rightArg);
Cell *cell = getCell(cellCoord.first, cellCoord.second);
// if cell not found or cell can't be computed => error
if (cell == NULL || !cell->compute() || !cell->isNumber())
{
this->error = true;
this->computed = true;
this->data = "#incorrect_cell_"+rightArg;
return false;
}
rightValue = cell->getNumber();
}
// Compute operation
switch (signState)
{
case EQUAL: leftValue = rightValue; break;
case PLUS: leftValue += rightValue; break;
case MINUS: leftValue -= rightValue; break;
case MULTIPLICATION: leftValue *= rightValue; break;
case DIVISION:
if (rightValue == 0)
{
this->error = true;
this->computed = true;
this->data = "#division_by_zero";
return false;
}
leftValue /= rightValue;
break;
}
}
if ( i == data.size()-1 )
break;
// set next sing
if (data[i] == '+')
signState = PLUS;
if (data[i] == '-')
signState = MINUS;
if (data[i] == '*')
signState = MULTIPLICATION;
if (data[i] == '/')
signState = DIVISION;
}
this->error = false;
this->computed = true;
this->data = std::to_string(leftValue);
this->data_int = leftValue;
return true;
}
