#!/usr/bin/perl 

1;

##################################################################
### arithmetic model (table or equation or trivial) evaluation ###
##################################################################

sub ALF_EvaluateArithmeticModel {	local($model,%arg) = @_;
	print("# ALF Math Info:\tevaluating arithmetic model $model\t",&ALF_ObjectInfoText($model),"\n") if ($ALF_Debug > 1);
	local $header = &ALF_FindMatchingObject($model,'HEADER');
	local $equation = &ALF_FindMatchingObject($model,'EQUATION');
	local $table = &ALF_FindMatchingObject($model,'TABLE');
	local $value = $ALF_Value{$model};
	local $result;
### trivial arithmetic model
	if (defined($value)) {
		$result = $value;
### equation or table
	} elsif ($header) {
		local %val = ();
		local $valid = 1;
		local @keys = keys %arg;
		foreach $key (@keys) {
			local $namematch = &ALF_FindMatchingObject($header,undef,$key);
			local $typematch = &ALF_FindMatchingObject($header,$key,0);
			local $match = $namematch || $typematch;
			if ($match) {
				local $val = $arg{$key};
				print("# ALF Math Info:\tidentified argument $match with value $val for model $model\t",&ALF_ObjectInfoText($match),"\n") if ($ALF_Debug > 1);
				$val{&UpperCase($key)} = $val if $equation;
				$val{$match} = $val if $table;
			} else {
				$valid = 0;
			}
		}
		local @val = keys %val;
		$result = &ALF_EvaluateArithmeticExpression($ALF_Value{$equation},%val) if $equation;
		$result = &ALF_EvaluateTable($ALF_Value{$table},0,$#val,%val) if $table;
	} else {
	}
	print("# ALF Math Info:\tevaluation result for arithmetic model $model(",join(' ',%arg),") = $result\n") if ($ALF_Debug > 1);
	$result;
}

########################################
### arithmetic expression processing ###
########################################

sub ALF_EvaluateArithmeticExpression {	local($expression,%arg) = @_;
	local @result = ();
	foreach $item (&Array($expression)) {
		$result[$#result+1] = &ALF_ReplaceItem($item,%arg);
	}
	local $result = eval(join(' ',@result));
	print("# ALF Math Info:\t$result = ",join(' ',@result),"\n") if ($ALF_Debug > 1);
	$result;
}

###############################
### lookup table processing ###
###############################

sub ALF_FindMatchingIndex {	local ($match,*table) = @_;
	local $found;
	foreach $index (0..$#table) {
		$found = $index if &StringMatch($table[$index],$match);
		last if defined($found);
	} $found;
}

sub ALF_FindFloorIndex {	local ($match,*table) = @_;
	local $found;
	foreach $index (reverse 0..$#table) {
		$found = $index unless ($table[$index] > $match);
		last if defined($found);
	}
	defined($found)? $found : 0;
}

sub ALF_FindCeilingIndex {	local ($match,*table) = @_;
	local $found;
	foreach $index (0..$#table) {
		$found = $index unless ($table[$index] < $match);
		last if defined($found);
	}
	defined($found)? $found : $#table;
}

sub ALF_FindInterpolationIndices {	local ($match,*table) = @_;
	local $lower = &ALF_FindFloorIndex($match,*table);
	local $upper = &ALF_FindCeilingIndex($match,*table);
	if ($lower == $upper) {
		if ($upper > 0) { $lower = $lower - 1; } else { $upper = 1; }
	}
	($lower,$upper);
}

sub ALF_EvaluateTable {	local($table,$tableoffset,$count,%arg) = @_;
#	local @key = sort(keys %arg);
	local @key = keys %arg;
	if ($ALF_Debug > 1) {
		print("# ALF Math Info:\tstarted evaluation of ",$count+1,"D table $table\ttableoffset[$table]=$tableoffset\t%x=(",join(' ',%arg),")\n") if ($count==$#key);
		print("# ALF Math Info:\t\ttableoffset[$table]=$tableoffset\t%x=(",join(' ',%arg),")\n") unless ($count==$#key);
	}
	local $key = $key[$count];
	local $keytable  = &AssocVal($ALF_KeyTable{$table}, $key);
	local $keyoffset = &AssocVal($ALF_KeyOffset{$table},$key);
	local $x = $arg{$key};
	local ($lower,$upper) = &ALF_FindInterpolationIndices($x,$keytable);		
	local $x0 = &ArrayVal($keytable,$lower);
	local $x1 = &ArrayVal($keytable,$upper);
	local $lowerindex = $tableoffset+$keyoffset*$lower;
	local $upperindex = $tableoffset+$keyoffset*$upper;
	if ($ALF_Debug > 1) {
		print("# ALF Math Info:\t\tkey[$count]=$key\n");
		print("# ALF Math Info:\t\tkeyoffset{$key}=$keyoffset\tkeytable{$key}=$keytable=(",join(' ',&Array($keytable)),")\n");
		print("# ALF Math Info:\t\tx{$key}=$x\tx0=$keytable\[$lower\]=$x0\tx1=$keytable\[$upper\]=$x1\n");
	}
	local ($y0,$y1);
	if ($count > 0) {
		$y0 = &ALF_EvaluateTable($table,$lowerindex,$count-1,%arg);
		$y1 = &ALF_EvaluateTable($table,$upperindex,$count-1,%arg);
	} else {
		$y0 = &ArrayVal($table,$lowerindex);
		$y1 = &ArrayVal($table,$upperindex);
	}
	local $y = $y0 + ($y1-$y0)*($x-$x0)/($x1-$x0);
	if ($ALF_Debug > 1) {
		print("# ALF Math Info:\t\ty($x)=$y\ty0=$table\[$lowerindex\]=$y0\ty1=$table\[$upperindex\]=$y1\n");
		print("# ALF Math Info:\tfinished evaluation of ",$count+1,"D table $table\ttableoffset[$table]=$tableoffset\ty(",join(' ',%arg),")=$y\n") if ($count==$#key);
	}
	$y;
}