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<?php |
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namespace kalanis\RemoteRequest\Protocols\Fsp\Traits; |
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/** |
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* Trait TChecksum |
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* @package kalanis\RemoteRequest\Protocols\Fsp\Traits |
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* Process checksums |
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/-* assume that we have already zeroed checksum in packet - that means set it to zero - chr(0) *-/ |
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unsigned int sum,checksum; |
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unsigned char *t; |
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for(t = packet_start, sum = 0; t < packet_end; sum += *t++); |
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checksum= sum + (sum >> 8); |
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* PHP, Perl |
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$len = strlen($packet); |
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$packet[1] = chr(0); // at first null checksum in packet |
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$sum = 0; // or $len for client->server |
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for ($i = 0; $i < $len; $i++) { |
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$sum += ord($packet[$i]); |
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} |
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$checksum = ($sum + ($sum >> 8)); |
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$byteChecksum = $checksum & 0xff; |
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*/ |
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trait TChecksum |
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{ |
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/* |
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* Slower, can be understand and ported |
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*/ |
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// protected function computeCheckSum(): int |
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// { |
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// $data = $this->getChecksumPacket(); |
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// $len = strlen($data); |
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// $sum = $this->getInitialSumChunk(); |
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// for ($i = 0; $i < $len; $i++) { |
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// $sum += ord($data[$i]); |
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//// print_r(['chkcc', $i, ord($data[$i]), $sum]); |
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// } |
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// $checksum = ($sum + ($sum >> 8)); |
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//// var_dump(['chks', $sum, decbin($sum), decbin($sum >> 8)]); |
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// return $checksum & 0xff; // only byte |
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// } |
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/* |
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* Faster, less intelligible |
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*/ |
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protected function computeCheckSum(): int |
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{ |
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$sum = array_reduce((array) str_split($this->getChecksumPacket()), [$this, 'sumBytes'], $this->getInitialSumChunk()); |
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return ($sum + ($sum >> 8)) & 0xff; |
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} |
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abstract protected function getChecksumPacket(): string; |
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abstract protected function getInitialSumChunk(): int; |
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public function sumBytes(int $sum, string $char): int |
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{ |
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return $sum + ord($char); |
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} |
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} |
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alex-kalanis /
remote-request
