271 lines
8.8 KiB
PHP
271 lines
8.8 KiB
PHP
<?php
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use Symfony\Component\ExpressionLanguage\ExpressionLanguage;
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require_once "PythonUtils.php";
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class LogicFunction implements JsonSerializable
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{
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private static ExpressionLanguage $EXP_LANG; // expression language for linting an evaluation
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private array $input_vars; // array of input variables
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private string $expression; // the logic function in the bitwise Verilog-form
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public static function convertToVerilogBitwiseForm(string $expression): string
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{
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return str_replace(["/", "!", "*", "+"], ["~", "~", "&", "|"], $expression);
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}
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public static function adaptToEL(string $expression): string
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{
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return str_replace(["~"], [" not "], $expression);
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}
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public static function collectVariables(string $expression): array
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{
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preg_match_all("/\w/", $expression, $variables);
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return array_filter(array_unique($variables[0]), fn($v) => !empty($v) && !is_numeric($v[0]));
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}
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public function __construct(string $expression = "", array $input_vars = [])
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{
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$this->setExpression($expression);
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$this->setInputVars(($input_vars === []) ? self::collectVariables($this->expression) : $input_vars);
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}
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public function getTruthTable(): string
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{
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$N = count($this->input_vars);
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if ($N == 0) {
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return "";
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}
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$M = pow(2, $N);
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$vars = [];
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foreach ($this->input_vars as $var) {
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$vars[$var] = 0;
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}
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$expression = self::adaptToEL($this->getExpression("verilog_logic"));
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// printf("Cooked: %s\n", $cooked_form);
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$tt = [];
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for ($i = 0; $i < $M; $i++) {
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for ($k = 0; $k < $N; $k++) {
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$vars[$this->input_vars[$k]] = (($i >> ($N - $k - 1)) & 1) === 1;
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// printf("%d ", $vars[$this->input_vars[$k]]);
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}
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$out = self::$EXP_LANG->evaluate($expression, $vars);
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$out_str = $out ? "1" : "0";
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// printf("%d\n", $out);
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$tt[] = $out_str;
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}
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return join("", $tt);
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}
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public static function genTerm(array $vars, int $ftn, int $tn, int $mind, int $maxd, bool $top = true, int $opindex = 1): string
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{
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$term = "";
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$m = max($ftn, random_int(1, $tn));
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if ((($maxd === 0) || ($m === 1)) && ($ftn === 0)) {
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$neg = random_int(0, 1) === 1;
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$var = $vars[array_rand($vars, 1)];
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$term = ($neg ? "~" : "") . $var;
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} else {
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$depth = random_int(0, max(0, $maxd - 1));
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$verilog_ops = [" & ", " | "];
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$verilog_op = $verilog_ops[$opindex];
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$term = !$top ? "(" : "";
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$nextopindex = ($opindex === 0) ? 1 : 0;
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for ($i = 0; $i < $m; $i++) {
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$subterm = self::genTerm($vars, (($mind - 1) > 0) ? $ftn : 0, $tn, $mind - 1, $depth, false, $nextopindex);
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$term .= $subterm;
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if ($i < $m - 1) {
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$term .= $verilog_op;
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}
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}
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$term .= !$top ? ")" : "";
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}
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return $term;
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}
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public static function genRandom(array $input_vars, int $min_depth = 2, int $max_depth = 3): LogicFunction
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{
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$term = self::genTerm($input_vars, count($input_vars), count($input_vars), $min_depth, $max_depth);
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return new LogicFunction($term, $input_vars);
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}
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public static function genRandomDNF($input_vars): LogicFunction
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{
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$N = count($input_vars);
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$states = pow(2, $N);
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$verilog_term = "";
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for ($i = 0; $i < $states; $i++) {
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$inside = "";
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$omit = random_int(0, 1); // omit the term or not?
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if (!$omit) {
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for ($j = 0; $j < $N; $j++) {
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$neg = !($i & (1 << $j)); // is it an inverted variable?
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$term = $input_vars[$j];
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if ($neg) {
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$inside .= "~" . $term;
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} else {
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$inside .= $term;
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}
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if ($j < ($N - 1)) {
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$inside .= " & ";
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}
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}
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}
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if ($inside !== "") {
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$verilog_term .= "(";
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$verilog_term .= $inside;
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$verilog_term .= ")";
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if (($i < ($states - 1)) && !$omit) {
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$verilog_term .= " | ";
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}
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}
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}
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$verilog_term = rtrim($verilog_term, "| ");
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return new LogicFunction($verilog_term, $input_vars);
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}
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public function setExpression(string $expression): void
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{
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$this->expression = self::convertToVerilogBitwiseForm($expression);
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}
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public function getExpression(string $fmt = "verilog_bitwise"): string
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{
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switch (strtolower($fmt)) {
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case "verilog_logic":
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return str_replace(["&", "|", "~"], ["&&", "||", "!"], $this->expression);
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case "tex":
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{
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$tex_form = str_replace([" | ", " & ", "(", ")"], [" + ", " \\cdot ", "\\left(", "\\right)"], $this->expression);
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return preg_replace("/~([a-zA-Z0-9_])/", '\\overline{$1}', $tex_form);
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}
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default:
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case "verilog_bitwise":
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return $this->expression;
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}
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}
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public function getInputVars(): array
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{
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return $this->input_vars;
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}
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public function setInputVars(array $input_vars): void
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{
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$this->input_vars = $input_vars;
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}
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public function getNStates(): int
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{
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return pow(2, count($this->input_vars));
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}
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public function isValid(): bool
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{
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try {
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self::$EXP_LANG->lint(self::adaptToEL($this->expression), $this->input_vars);
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} catch (Exception $e) {
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return false;
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}
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return true;
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}
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public function toArray(): array
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{
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return ["expression" => $this->expression, "input_vars" => $this->input_vars];
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}
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public function jsonSerialize()
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{
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return $this->toArray();
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}
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public static function fromArray(array $a): LogicFunction
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{
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return new LogicFunction($a["expression"] ?? "", $a["input_vars"] ?? []);
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}
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// general minterm regex: ([/!~]*[a-zA-Z_][a-zA-Z0-9_]*[&]{1,2})*([/!~]*[a-zA-Z_][a-zA-Z0-9_]*)
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// specific regex: ([\/!~]*(<input vars>)[&]{1,2})*([\/!~]*(<input vars>))
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public static function isCorrectDNF(array $input_vars, string $exp): bool
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{
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$exp = trim($exp); // trim spaces
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if ($exp === "0") {
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return true;
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}
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$minterms = explode("|", $exp); // break up the expression into minterms
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$minterms = array_map(fn($mt) => trim($mt, " ()\t"), $minterms); // strip the parentheses off the minterms
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$minterms = array_map(fn($mt) => str_replace(" ", "", $mt), $minterms); // remove spaces
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$ivars = implode("|", $input_vars); // create | separated list of input vars to be used with the regular expression
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$regex = "/([\/!~]*(${ivars})[&]{1,2})*([\/!~]*(${ivars}))/"; // specific regular expression
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foreach ($minterms as $minterm) {
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if (preg_match($regex, $minterm) !== 1) { // generally try to match the minterm
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return false;
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}
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preg_match_all("/[\/!~]*(${ivars})[&]*/", $minterm, $matches); // fetch variables
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$vars = $matches[1] ?? [];
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sort($vars); // sort detected variables
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sort($input_vars); // sort input variables
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if ($vars !== $input_vars) { // ensure each variable occurs just once
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return false;
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}
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}
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return true;
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}
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public static function initStatic(): void
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{
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self::$EXP_LANG = new ExpressionLanguage();
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}
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public function toDNF(): string
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{
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$N = count($this->input_vars);
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$M = pow(2, count($this->input_vars));
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$tt = $this->getTruthTable();
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$minterms = [];
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for ($i = 0; $i < $M; $i++) {
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$r = $tt[$i];
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if ($r == "1") {
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$term = "(";
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for ($j = 0; $j < $N; $j++) {
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$inv = (($i >> ($N - $j - 1)) & 1) ? "" : "~";
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$term .= $inv . $this->input_vars[$j];
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if ($j < ($N - 1)) {
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$term .= " & ";
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}
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}
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$term .= ")";
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$minterms[] = $term;
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}
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}
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$dnf = join(" | ", $minterms);
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if ($dnf === "") {
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$dnf = "0";
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}
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return $dnf;
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}
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public function drawNetwork(string $outvar = "f"): string
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{
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$expr = str_replace(["^"], [" xor "], $this->getExpression());
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return PythonUtils::execPy("draw_logic_network.py", [$expr, $outvar]);
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}
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}
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LogicFunction::initStatic(); |