### timing semantics ###

sub ALF_IsPositiveUnate {	local($fromedge,$toedge) = @_;
	&ALF_IsRisingEdge($fromedge) && &ALF_IsRisingEdge($toedge) ||
	&ALF_IsFallingEdge($fromedge) && &ALF_IsFallingEdge($toedge);
}
sub ALF_IsNegativeUnate {	local($fromedge,$toedge) = @_;
	&ALF_IsFallingEdge($fromedge) && &ALF_IsRisingEdge($toedge) ||
	&ALF_IsRisingEdge($fromedge) && &ALF_IsFallingEdge($toedge);
}

sub ALF_IsRisingEdge {	local($edge) = @_;
	local ($initial,$final) = &ALF_GetBitLiterals($edge);
	(&ALF_LogicalValue($initial) ne &ALF_LogicalValue($final))
	&& (	(&ALF_LogicalValue($initial) eq 'false')
	||	(&ALF_LogicalValue($final) eq 'true')
	);
}
sub ALF_IsFallingEdge {	local($edge) = @_;
	local ($initial,$final) = &ALF_GetBitLiterals($edge);
	(&ALF_LogicalValue($initial) ne &ALF_LogicalValue($final))
	&& (	(&ALF_LogicalValue($initial) eq 'true')
	||	(&ALF_LogicalValue($final) eq 'false')
	);
}

sub ALF_IsThreeStateEnable {	local($edge) = @_;
	local ($initial,$final) = &ALF_GetBitLiterals($edge);
	(&ALF_DriveStrength($initial) eq 'zero') &&
	(&ALF_DriveStrength($final) ne 'zero');
}
sub ALF_IsThreeStateDisable {	local($edge) = @_;
	local ($initial,$final) = &ALF_GetBitLiterals($edge);
	(&ALF_DriveStrength($initial)  ne 'zero') &&
	(&ALF_DriveStrength($final) eq 'zero');
}

### access to timing data ###

sub ALF_TimingArc {	local($object) = @_;
	local $vector = &ALF_FindAncestor($object,'VECTOR');
	local $expression = $ALF_Expression{$vector};
	local $from = &ALF_FindMatchingObject($object,'FROM');
	local ($fromedge,$frompin) = &ALF_TimingEdge($from,$expression) if defined($from);
	local $to = &ALF_FindMatchingObject($object,'TO');
	local ($toedge,$topin) = &ALF_TimingEdge($to,$expression) if defined($to);
	print("# ALF Data Error:\tobject $object ",&ALF_ObjectInfoText($object)," has incomplete timing arc\n")
		unless (defined($fromedge) && defined($frompin) && defined($toedge) && defined ($topin));
	($fromedge,$frompin,$toedge,$topin);
}

sub ALF_TimingEdge {	local($object,$expression) = @_;
	local $pin_annotation = &ALF_FindMatchingObject($object,'PIN');
	local $edge_number = &ALF_FindMatchingObject($object,'EDGE_NUMBER');
	local ($pin,$edge);
	if (defined($pin_annotation)) {
		$pin = $ALF_Value{$pin_annotation};
		$edge = &ALF_FindEdgeLiteral($expression,$pin,$edge_number);
	}
	($edge,$pin);
}

sub ALF_TimingThresholds {	local($parent,$type) = @_;
	local $model = &ALF_FindMatchingObject($parent,$type,0);
	local ($from_rise,$from_fall,$to_rise,$to_fall);
	if (defined($model)) {
		local $from = &ALF_FindMatchingObject($model,'FROM');
		($from_rise,$from_fall) = &ALF_TimingThreshold($from);
		local $to = &ALF_FindMatchingObject($model,'TO');
		($to_rise,$to_fall) = &ALF_TimingThreshold($to);
	}
	($from_rise,$from_fall,$to_rise,$to_fall);
}


sub ALF_TimingThreshold {	local($parent) = @_;
	local $threshold = &ALF_FindMatchingObject($parent,'THRESHOLD');
	local ($rise,$fall);
	if (defined($threshold)) {
		$rise = &ALF_FindMatchingObject($threshold,'RISE');
		$fall = &ALF_FindMatchingObject($threshold,'FALL');
	}
	defined($ALF_Value{$threshold})? ($threshold,$threshold) : ($rise,$fall);
}

### Liberty timing semantics ###

sub ALF_LibertyTimingAnnotations {	local(@timing_objects) = @_;
	local ($combinational,$three_state_enable,$three_state_disable,$rising_edge,$falling_edge,$preset,$clear);
	local ($setup_rising,$setup_falling);
	local ($hold_rising,$hold_falling);
	local ($recovery_rising,$recovery_falling);
	local ($removal_rising,$removal_falling);
	foreach $object (@timing_objects) {
		local $alf_type = $ALF_Type{$object};
		if (&StringMatch($alf_type,'DELAY')) {
			$combinational = 1;
			$three_state_enable = 1;
			$three_state_disable = 1;
			$rising_edge = 1;
			$falling_edge = 1;
			$preset = 1;
			$clear = 1;
		} elsif (&StringMatch($alf_type,'SETUP')) {
			$setup_rising = 1;
			$setup_falling = 1;
		} elsif (&StringMatch($alf_type,'HOLD')) {
			$hold_rising = 1;
			$hold_falling = 1;
		} elsif (&StringMatch($alf_type,'RECOVERY')) {
			$recovery_rising = 1;
			$recovery_falling = 1;
		} elsif (&StringMatch($alf_type,'REMOVAL')) {
			$removal_rising = 1;
			$removal_falling = 1;
		}
	}
	local $positive_unate = 1;
	local $negative_unate = 1;
	foreach $object (@timing_objects) {
		local ($fromedge,$frompin,$toedge,$topin) = &ALF_TimingArc($object);
		$positive_unate = $positive_unate && &ALF_IsPositiveUnate($fromedge,$toedge);
		$negative_unate = $negative_unate && &ALF_IsNegativeUnate($fromedge,$toedge);
		local $alf_type = $ALF_Type{$object};
		if (&StringMatch($alf_type,'DELAY')) {
			$three_state_enable = $three_state_enable && &ALF_IsThreeStateEnable($toedge);
			$three_state_disable = $three_state_disable && &ALF_IsThreeStateDisable($toedge);
			$rising_edge = $rising_edge && &ALF_IsRisingEdge($fromedge);
			$falling_edge = $falling_edge && &ALF_IsFallingEdge($fromedge);
			$preset = $preset && &ALF_IsRisingEdge($toedge);
			$clear = $clear && &ALF_IsFallingEdge($toedge);
#print("delay($fromedge $frompin -> $toedge $topin):\tcomb=$combinational\t3enb=$three_state_enable\t3dis=$three_state_disable\trise=$rising_edge\tfall=$falling_edge\tpreset=$preset\tclear=$clear\n");
		} elsif (&StringMatch($alf_type,'SETUP')) {
			$setup_rising = $setup_rising && &ALF_IsRisingEdge($toedge);
			$setup_falling = $setup_falling && &ALF_IsFallingEdge($toedge);
#print("setup($fromedge $frompin -> $toedge $topin):\trise=$setup_rising\tfall=$setup_falling\n");
		} elsif (&StringMatch($alf_type,'HOLD')) {
			$hold_rising = $hold_rising && &ALF_IsRisingEdge($fromedge);
			$hold_falling = $hold_falling && &ALF_IsFallingEdge($fromedge);
#print("hold($fromedge $frompin -> $toedge $topin):\trise=$hold_rising\tfall=$hold_falling\n");
		} elsif (&StringMatch($alf_type,'RECOVERY')) {
			$recovery_rising = $recovery_rising && &ALF_IsRisingEdge($toedge);
			$recovery_falling = $recovery_falling && &ALF_IsFallingEdge($toedge);
#print("recovery($fromedge $frompin -> $toedge $topin):\trise=$recovery_rising\tfall=$recovery_falling\n");
		} elsif (&StringMatch($alf_type,'REMOVAL')) {
			$removal_rising = $removal_rising && &ALF_IsRisingEdge($fromedge);
			$removal_falling = $removal_falling && &ALF_IsFallingEdge($fromedge);
#print("removal($fromedge $frompin -> $toedge $topin):\trise=$removal_rising\tfall=$removal_falling\n");
		}
	}
	local $timing_type
	=	$three_state_enable? 'three_state_enable'
	:	$three_state_disable? 'three_state_disable'
	:	$preset? 'preset'
	:	$clear? 'clear'
	:	$rising_edge? 'rising_edge'
	:	$falling_edge? 'falling_edge'
	:	$setup_rising? 'setup_rising'
	:	$setup_falling? 'setup_falling'
	:	$hold_rising? 'hold_rising'
	:	$hold_falling? 'hold_falling'
	:	$recovery_rising? 'recovery_rising'
	:	$recovery_falling? 'recovery_falling'
	:	$removal_rising? 'removal_rising'
	:	$removal_falling? 'removal_falling'
	:	$combinational? 'combinational'
	:	undef;
	local $timing_sense
	=	( $positive_unate && !$negative_unate)? 'positive_unate'
	:	( $negative_unate && !$positive_unate)? 'negative_unate'
	:	(!$positive_unate && !$negative_unate)? 'non_unate'
	:	undef;
	($timing_type,$timing_sense);
}

1;