//Input: A conditional expression x (at AND level)
//Output: The conditional expression !x
NC* negateConditionalExpression( NC *cond )
{
NC *negCond;
if(cond == NULL)
return NULL;
negCond = (NC*) malloc (sizeof(NC));
negCond->list = NULL;
negCond->type = 'A';
negCond->inc = 0;
negCond->link = computeNegation(cond->link);
return negCond;
}
//Input: A conditional expression x (at OR level)
//Output: The conditional expression !x
NC* computeNegation( NC *cond )
{
NC *retOr, *oldOr, *newOr;
NC *iRel, *oneRel;
NC *retNegCond, *jRet;
//base case
if(cond->list == NULL)
{
for(iRel = cond->link; iRel != NULL; iRel = iRel->list)
{
oneRel = (NC*) malloc (sizeof(NC));
oneRel->list = NULL;
oneRel->type = 'R';
oneRel->inc = negateoperator(iRel->inc);
oneRel->link = copylist(iRel->link);
newOr = (NC*) malloc (sizeof(NC));
newOr->list = NULL;
newOr->type = 'O';
newOr->inc = 0;
newOr->link = oneRel;
if(iRel == cond->link)
retOr = newOr;
else
oldOr->list = newOr;
oldOr = newOr;
}
return retOr;
}
//inductive case
retNegCond = computeNegation( cond->list );
for(iRel = cond->link; iRel != NULL; iRel = iRel->list)
{
for(jRet = retNegCond; jRet != NULL; jRet = jRet->list)
{
oneRel = (NC*) malloc (sizeof(NC));
oneRel->list = copylist(jRet->link);
oneRel->type = 'R';
oneRel->inc = negateoperator(iRel->inc);
oneRel->link = copylist(iRel->link);
newOr = (NC*) malloc (sizeof(NC));
newOr->list = NULL;
newOr->type = 'O';
newOr->inc = 0;
newOr->link = oneRel;
if(iRel == cond->link)
retOr = newOr;
else
oldOr->list = newOr;
oldOr = newOr;
}
}
return retOr;
}
int computeOperation(astNode* exprNode, symTab* symtab) {
astNode* lhs = exprNode->leftMostChild;
if(lhs != NULL && lhs->type == OPERATOR)
return(computeNegation(lhs, symtab));
astNode* operator = lhs->rightSibling;
astNode* rhs = operator->leftMostChild;
short rhsReg = -1;
short lhsReg = -1;
/* Left Hand Side */
if (lhs == NULL || lhs->type == NULLNODE) {
lhsReg = -1;
} else if(lhs->type == EXPR || lhs->type == OPERATION) {
if(computeExpression(lhs, symtab) >= 0) {
lhsReg = 0;
}
} else if(lhs->type == NUMBER) { // Loading number into temp
fprintf(yyoutasm, "\tli\t$t0, %d\t\t# Load %d into $t0\n", lhs->intVal, lhs->intVal);
lhsReg = 0;
pushStackReg("$t0", symtab);
} else if (lhs->type == VAR){
varToStack(lhs, symtab);
lhsReg = 0;
}
/* Right Hand Side */
if (rhs == NULL || rhs->type == NULLNODE) {
rhsReg = -1;
}
else if(rhs->type == EXPR || rhs->type == OPERATION) {
if(computeExpression(rhs, symtab) >= 0) {
rhsReg = 1;
}
} else if(rhs->type == NUMBER) { // Loading number into temp
fprintf(yyoutasm, "\tli\t$t1, %d\n", rhs->intVal);
rhsReg = 1;
pushStackReg("$t1", symtab);
} else if (rhs->type == VAR){
varToStack(rhs, symtab);
rhsReg = 1;
}
fprintf(yyoutasm, "\t# Operation\n");
if(lhsReg < 0 && rhsReg < 0) {
fprintf(yyoutasm, "\t# End operation\n");
return 0;
}
else if(lhsReg < 0) {
fprintf(yyoutasm, "\t# End operation\n");
return 1;
}
else if(rhsReg < 0) {
fprintf(yyoutasm, "\t# End operation\n");
return 1;
}
else {
popStackReg("$t1", symtab); // RHS
popStackReg("$t0", symtab); // LHS
switch(operator->operator) {
case '+':
fprintf(yyoutasm, "\tadd\t$t2, $t0, $t1\t# Add $t0 and $t1 and store in $t2\n");
break;
case '-':
fprintf(yyoutasm, "\tsub\t$t2, $t0, $t1\t# Subtract $t0 and $t1 and store in $t2\n");
break;
case '*':
fprintf(yyoutasm, "\tmult\t$t0, $t1\t# Multiply $t0 and $t1\n");
fprintf(yyoutasm, "\tmflo\t$t2\t# Store result in $t2\n");
break;
case '/':
fprintf(yyoutasm, "\tdiv\t$t0, $t1\t# Divide $t0 and $t1\n");
fprintf(yyoutasm, "\tmflo\t$t2\t# Store result in $t2\n");
break;
case '<':
fprintf(yyoutasm, "\tli\t$t2, -1\n"); // True
fprintf(yyoutasm, "\tblt\t$t0, $t1, e%d\n", labelCount); // If lhs < rhs, jump next stmt
fprintf(yyoutasm, "\tnop\n");
fprintf(yyoutasm, "\tli\t$t2, 0\n"); // False
fprintf(yyoutasm, "e%d:\n", labelCount++);
break;
case '=':
fprintf(yyoutasm, "\tli\t$t2, -1\n"); // True
fprintf(yyoutasm, "\tbeq\t$t0, $t1, e%d\n", labelCount); // If lhs = rhs, jump next stmt
fprintf(yyoutasm, "\tnop\n");
fprintf(yyoutasm, "\tli\t$t2, 0\n"); // False
fprintf(yyoutasm, "e%d:\n", labelCount++);
break;
case '&':
fprintf(yyoutasm, "\tli\t$t2, 0\n"); // False
fprintf(yyoutasm, "\tbeq\t$t0, $0, e%d\n", labelCount); // If lhs = 0 (false), we jump over the whole stmt and evaluate to false
fprintf(yyoutasm, "\tnop\n");
fprintf(yyoutasm, "\tbeq\t$t1, $0, e%d\n", labelCount); // Otherwise, lhs is true and we evaluate rhs
fprintf(yyoutasm, "\tnop\n");
fprintf(yyoutasm, "\tli\t$t2, -1\n"); // True
fprintf(yyoutasm, "e%d:\n", labelCount++);
break;
case '|':
fprintf(yyoutasm, "\tli\t$t2, -1\n"); // True
fprintf(yyoutasm, "\tbne\t$t0, $0, e%d\n", labelCount); // If lhs != 0 (true), we jump over the whole stmt and evaluate to true
fprintf(yyoutasm, "\tnop\n");
fprintf(yyoutasm, "\tbne\t$t1, $0, e%d\n", labelCount); // Otherwise, lhs is false and we evaluate rhs
fprintf(yyoutasm, "\tnop\n");
fprintf(yyoutasm, "\tli\t$t2, 0\n"); // False
fprintf(yyoutasm, "e%d:\n", labelCount++);
break;
default:
break;
}
}
pushStackReg("$t2", symtab); // Push on stack
fprintf(yyoutasm, "\t# End operation\n");
return 1;
}
