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Pad the subexpression of unary not. 

The operand of unary not needs to be padded to the expression width
before the operator itself. Otherwise, the high (pad) bits will come
out wrong.
This commit is contained in:
Stephen Williams 2008-10-12 21:38:07 -07:00
parent 62f518c205
commit 55b8ff4441
2 changed files with 34 additions and 2 deletions
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3
PExpr.h
View File

@ -444,6 +444,9 @@ class PEUnary : public PExpr {
virtual bool is_constant(Module*) const;
private:
NetExpr* elaborate_expr_bits_(NetExpr*operand, int expr_wid) const;
private:
char op_;
PExpr*expr_;

33
elab_expr.cc
View File

@ -2716,6 +2716,7 @@ unsigned PEUnary::test_width(Design*des, NetScope*scope,
// then the tested width.
case '-':
case '+':
case '~':
if (test_wid < min)
test_wid = min;
break;
@ -2854,10 +2855,38 @@ NetExpr* PEUnary::elaborate_expr(Design*des, NetScope*scope,
break;
case '~':
tmp = new NetEUBits(op_, ip);
tmp->set_line(*this);
tmp = elaborate_expr_bits_(ip, expr_wid);
break;
}
return tmp;
}
NetExpr* PEUnary::elaborate_expr_bits_(NetExpr*operand, int expr_wid) const
{
// Handle the special case that the operand is a
// constant. Simply calculate the constant results of the
// expression and return that.
if (NetEConst*ctmp = dynamic_cast<NetEConst*> (operand)) {
verinum value = ctmp->value();
if (expr_wid > (int)value.len())
value = pad_to_width(value, expr_wid);
// The only operand that I know can get here is the
// unary not (~).
ivl_assert(*this, op_ == '~');
value = v_not(value);
ctmp = new NetEConst(value);
ctmp->set_line(*this);
delete operand;
return ctmp;
}
if (expr_wid > (int)operand->expr_width())
operand = pad_to_width(operand, expr_wid);
NetEUBits*tmp = new NetEUBits(op_, operand);
tmp->set_line(*this);
return tmp;
}