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Use undef (x/z vs. NaN) rules for real values from IEEE Std 1800-2012

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This commit is contained in:
Clifford Wolf 2014-06-16 15:05:37 +02:00
parent 0c4c79c4c6
commit 82bbd2f077
2 changed files with 11 additions and 0 deletions
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2
frontends/ast/ast.cc
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@ -783,6 +783,8 @@ double AstNode::asReal(bool is_signed)
double v = 0;
for (size_t i = 0; i < val.bits.size(); i++)
// IEEE Std 1800-2012 Par 6.12.2: Individual bits that are x or z in
// the net or the variable shall be treated as zero upon conversion.
if (val.bits.at(i) == RTLIL::State::S1)
v += exp2(i);
if (is_negative)

9
frontends/ast/simplify.cc
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@ -1625,6 +1625,15 @@ skip_dynamic_range_lvalue_expansion:;
if (a.bits[i] != b.bits[i])
a.bits[i] = RTLIL::State::Sx;
newNode = mkconst_bits(a.bits, sign_hint);
} else if (children[1]->isConst() && children[2]->isConst()) {
newNode = new AstNode(AST_REALVALUE);
if (children[1]->asReal(sign_hint) == children[2]->asReal(sign_hint))
newNode->realvalue = children[1]->asReal(sign_hint);
else
// IEEE Std 1800-2012 Sec. 11.4.11 states that the entry in Table 7-1 for
// the data type in question should be returned if the ?: is ambiguous. The
// value in Table 7-1 for the 'real' type is 0.0.
newNode->realvalue = 0.0;
}
}
break;