Aerys\HPack::encode PHP Method

    public static function encode($headers)
    {
        // @TODO implementation is deliberately primitive... [doesn't use any dynamic table...]
        $output = [];
        foreach ($headers as $name => $values) {
            foreach ((array) $values as $value) {
                foreach (self::TABLE as $index => list($header_name)) {
                    if ($name == $header_name) {
                        break;
                    }
                }
                if ($name == $header_name) {
                    if (++$index < 0x10) {
                        $output[] = \chr($index);
                    } else {
                        $output[] = "" . \chr($index - 0xf);
                    }
                } elseif (\strlen($name) < 0x7f) {
                    $output[] = "" . \chr(\strlen($name)) . $name;
                } else {
                    $output[] = "" . self::encode_dynamic_integer(\strlen($name) - 0x7f) . $name;
                }
                if (\strlen($value) < 0x7f) {
                    $output[] = \chr(\strlen($value)) . $value;
                } else {
                    $output[] = "" . self::encode_dynamic_integer(\strlen($value) - 0x7f) . $value;
                }
            }
        }
        return implode($output);
    }

 public function writer(InternalRequest $ireq) : \Generator
 {
     $client = $ireq->client;
     $id = $ireq->streamId;
     $headers = yield;
     unset($headers[":reason"], $headers["connection"]);
     // obsolete in HTTP/2.0
     $headers = HPack::encode($headers);
     // @TODO decide whether to use max-frame size
     if (\strlen($headers) > 16384) {
         $split = str_split($headers, 16384);
         $headers = array_shift($split);
         $this->writeFrame($client, $headers, self::HEADERS, self::NOFLAG, $id);
         $headers = array_pop($split);
         foreach ($split as $msgPart) {
             $this->writeFrame($client, $msgPart, self::CONTINUATION, self::NOFLAG, $id);
         }
         $this->writeFrame($client, $headers, self::CONTINUATION, self::END_HEADERS, $id);
     } else {
         $this->writeFrame($client, $headers, self::HEADERS, self::END_HEADERS, $id);
     }
     $msgs = "";
     while (($msgPart = yield) !== null) {
         $msgs .= $msgPart;
         if ($msgPart === false || \strlen($msgs) > $client->options->outputBufferSize) {
             $this->writeData($client, $msgs, $id, false);
             $msgs = "";
         }
         if ($client->isDead) {
             if (!$client->bufferPromisor) {
                 $client->bufferPromisor = new Deferred();
                 $client->bufferPromisor->fail(new ClientException());
             }
             while (true) {
                 yield;
             }
         }
     }
     $this->writeData($client, $msgs, $id, true);
     if ($client->isDead && !$client->bufferPromisor) {
         $client->bufferPromisor = new Failure(new ClientException());
     }
     if ($client->bufferPromisor) {
         $keepAlives =& $client->remainingKeepAlives;
         // avoid cyclic reference
         $client->bufferPromisor->when(static function () use(&$keepAlives) {
             $keepAlives++;
         });
     } else {
         $client->remainingKeepAlives++;
     }
 }