### boolean value and edge literal semantics ###

sub ALF_GetBitLiterals {	local($edge_literal) = @_;
	local $initial,$final;
	if ($edge_literal =~ /$ALF_bit_edge_literal/) {
		$initial = substr($edge_literal,0,1);
		$final = substr($edge_literal,1,1);
#print("bit_edge_literal $edge_literal: initial=$initial final=$final\n");
	} elsif ($edge_literal =~ /$ALF_symbolic_edge_literal/) {
		$initial = substr($edge_literal,0,1);
		$final = substr($edge_literal,1,1);
#print("symbolic_edge_literal $edge_literal: initial=$initial final=$final\n");
	} elsif ($edge_literal =~ /$ALF_based_edge_literal/ && (length($edge_literal)==6)) {
		$initial = substr($edge_literal,2,1);
		$final = substr($edge_literal,5,1);
#print("based_edge_literal $edge_literal: initial=$initial final=$final\n");
	}
	($initial,$final);
}

sub ALF_LogicalValue {	local($symbol) = @_;
	&StringMatch($symbol,'1','H')?	'true' :
	&StringMatch($symbol,'0','L')?	'false' :
	&StringMatch($symbol,'X','W')?	'unknown' :
	&StringMatch($symbol,'?')?	'arbitrary' :
	&StringMatch($symbol,'*')?	'random' :
	&StringMatch($symbol,'!')?	'changed' :
	&StringMatch($symbol,'~')?	'allchanged' :
	&StringMatch($symbol,'-')?	'unchanged' :
	undef;
}

sub ALF_DriveStrength {	local($symbol) = @_;
	&StringMatch($symbol,'1','0','X')?	'strong' :
	&StringMatch($symbol,'H','L','W')?	'weak' :
	&StringMatch($symbol,'Z')?	'zero' :
	undef;
}

sub ALF_Inverted {	local($symbol) = @_;
	local ($first,@symbol) = split(/\s+/,$symbol);
	&StringMatch($symbol,'1',"\47b1")? '0' :
	&StringMatch($symbol,'0',"\47b0")? '1' :
	&StringMatch($symbol,"\47bH")?	"\47bL" :
	&StringMatch($symbol,"\47bh")?	"\47bl" :
	&StringMatch($symbol,"\47bL")?	"\47bH" :
	&StringMatch($symbol,"\47bl")?	"\47bh" :
	&StringMatch($symbol,"\47bX")?	"\47bX" :
	&StringMatch($symbol,"\47bx")?	"\47bx" :
	&StringMatch($symbol,"\47bW")?	"\47bW" :
	&StringMatch($symbol,"\47bw")?	"\47bw" :
	&ALF_LexicalMatch('identifier',$symbol)? "! $symbol" :
	&StringMatch($first,'+')? join(' ','-',@symbol) :
	&StringMatch($first,'-')? join(' ','+',@symbol) :
	&StringMatch($first,'!','~')? join(' ',@symbol) :
	&ALF_LexicalMatch('edge_literal',$first)? join(' ',&ALF_InvertedEdge($first),@symbol) :
	defined($symbol)? "! ( $symbol )" :
	undef;
}

sub ALF_InvertedEdge {	local($edge_literal) = @_;
	local ($initial,$final) = &ALF_GetBitLiterals($edge_literal);
	join('',$final,$initial);
}

### boolean and vector expression semantics ###

sub ALF_Boolean2Edge {	local($expression) = @_;
	local ($expr0,$expr1,@expr2) = split(/\s/,$expression);
	($expr0 eq '!') &&  defined($expr1) && !defined(@expr2)? "10 $expr1" :
	($expr0 eq '!') &&  defined($expr1) &&  defined(@expr2)? "10 ( $expr1 @expr2 )" :
	defined($expr0) && !defined($expr1) && !defined(@expr2)? "01 $expr0" :
	defined($expr0) &&  defined($expr1) && !defined(@expr2)? "01 ( $expr0 $expr1 )" :
	defined($expr0) &&  defined($expr1) &&  defined(@expr2)? "01 ( $expr0 $expr1 @expr2 )" :
	undef;
}

sub ALF_Edge2Boolean {	local($expression) = @_;
	local ($expr0,$expr1,@expr2) = split(/\s/,$expression);
	&ALF_IsRisingEdge ($expr0) &&  defined($expr1) && !defined(@expr2)?    $expr1  :
	&ALF_IsFallingEdge($expr0) &&  defined($expr1) && !defined(@expr2)? "! $expr1" :
	&ALF_IsRisingEdge ($expr0) &&  defined($expr1) &&  defined(@expr2)?    "$expr1 @expr2"  :
	&ALF_IsFallingEdge($expr0) &&  defined($expr1) &&  defined(@expr2)? "! ($expr1 @expr2)" :
	undef;
}

sub ALF_SingleEvent {	local(*expression) = @_;
	local ($d0,$r0) = &ALF_ExpressionData($expression[0]);
	local ($d1,$r1) = &ALF_ExpressionData($expression[1]);
	($d0,$d1) if (($#expression == 1) && &StringMatch($r0,'single_event') && &StringMatch($r1,'identifier'));
}

sub ALF_BooleanExpression {	local(*expression) = @_;
	local $match;
	foreach $item (@expression) {
		local ($data,$rule) = &ALF_ExpressionData($item);
		$match = &StringMatch($rule,&Array($ALF_ExpressionRuleSet{'boolean_expression'}));
		last unless $match;
	} $match;
}

sub ALF_FindEdgeLiteral {	local(*expression,$pin,$edge_number) = @_;
	local $count = 0;
	local $edge_literal;
	foreach $item (@expression) {
		local ($data,$rule) = &ALF_ExpressionData($item);
		if ($edge_literal && &StringMatch($data,$pin)) {
			last if ($count==$edge_number);
			$count += 1;
		}
		$edge_literal = &StringMatch($rule,'single_event')? $data : undef;
	}
	$edge_literal;
}

sub ALF_FindBooleanExpression {	local(*expression) = @_;
	local $boolean = &CreateArray();
	local $vector_expression;
	local $boolean_expression;
	local $leftover;
	foreach $item (@expression) {
		local ($data,$rule) = &ALF_ExpressionData($item);
		local $start = &StringMatch($rule,'single_event');
		local $continue = &StringMatch($rule,'control_and vector_expression');
		local $finish = &StringMatch($rule,'control_and boolean_expression');
		$boolean_expression = &StringMatch($rule,&Array($ALF_ExpressionRuleSet{'boolean_expression'}));
		&AppendArray($boolean,$data) if ($boolean_expression && !$start && !$vector_expression || $continue);
		$vector_expression = ($start || $vector_expression) && !$finish;
		$leftover = !$finish && ($leftover || $continue);
	}
	!&ArraySize($boolean)? undef
	: $leftover? join(' ',&GetSubArray($boolean,0,&ArraySize($boolean)-2))
	: join(' ',&Array($boolean));
}

1;