beat codec

diff --git a/app/Beat/Decoder.php b/app/Beat/Decoder.php
new file mode 100644 (file)
index 0000000..7dc654c
--- /dev/null
+++ b/app/Beat/Decoder.php
@@ -0,0 +1,155 @@
+<?php
+
+namespace App\Beat;
+
+class Decoder {
+
+       public function __construct($source) {
+               $this->source = $source;
+       }
+
+       public function applyPatch($patch) {
+               $this->patch = $patch;
+               $this->patchCursor = 0;
+               $this->outputOffset = 0;
+               $this->sourceRelativeOffset = 0;
+               $this->targetRelativeOffset = 0;
+
+               $this->readHeader();
+               while ($this->hasAction()) {
+                       $this->handleAction();
+               }
+
+               $sourceCrc = $this->read32();
+               $targetCrc = $this->read32();
+               $patchCrc = $this->read32();
+
+               if (crc32($this->source) != $sourceCrc) {
+                       throw new Exception('source checksum mismatch');
+               }
+               if (crc32($this->target) != $targetCrc) {
+                       throw new Exception('target checksum mismatch');
+               }
+               if (crc32(substr($this->patch, 0, -4)) != $patchCrc) {
+                       throw new Exception('patch checksum mismatch');
+               }
+
+               return $this->target;
+       }
+
+
+       private function readHeader() {
+               $header = $this->readString(4);
+               if ($header != 'BPS1') {
+                       throw new Exception('invalid header: '.$header);
+               }
+
+               $sourceSize = $this->readNumber();
+               $targetSize = $this->readNumber();
+               $metadataSize = $this->readNumber();
+               $this->metadata = $this->readString($metadataSize);
+               if ($sourceSize != strlen($this->source)) {
+                       throw new Exception('source size mismatch. source: '.strlen($this->source).', patch: '.$sourceSize);
+               }
+               $this->target = str_repeat("\0", $targetSize);
+       }
+
+       private function hasAction() {
+               return $this->patchCursor < strlen($this->patch) - 12;
+       }
+
+       private function handleAction() {
+               $data = $this->readNumber();
+               $command = $data & 3;
+               $length = ($data >> 2) + 1;
+               switch ($command) {
+                       case 0:
+                               $this->handleSourceRead($length);
+                               break;
+                       case 1:
+                               $this->handleTargetRead($length);
+                               break;
+                       case 2:
+                               $this->handleSourceCopy($length);
+                               break;
+                       case 3:
+                               $this->handleTargetCopy($length);
+                               break;
+               }
+       }
+
+       private function handleSourceRead($length) {
+               while ($length--) {
+                       $this->target[$this->outputOffset] = $this->source[$this->outputOffset];
+                       ++$this->outputOffset;
+               }
+       }
+
+       private function handleTargetRead($length) {
+               while ($length--) {
+                       $this->target[$this->outputOffset++] = $this->readByte();
+               }
+       }
+
+       private function handleSourceCopy($length) {
+               $this->sourceRelativeOffset += $this->readSignedNumber();
+               while ($length--) {
+                       $this->target[$this->outputOffset++] = $this->source[$this->sourceRelativeOffset++];
+               }
+       }
+
+       private function handleTargetCopy($length) {
+               $this->targetRelativeOffset += $this->readSignedNumber();
+               while ($length--) {
+                       $this->target[$this->outputOffset++] = $this->target[$this->targetRelativeOffset++];
+               }
+       }
+
+       private function read32() {
+               $a = ord($this->readByte());
+               $b = ord($this->readByte());
+               $c = ord($this->readByte());
+               $d = ord($this->readByte());
+               return $a | ($b << 8) | ($c << 16) | ($d << 24);
+       }
+
+       private function readByte() {
+               return $this->patch[$this->patchCursor++];
+       }
+
+       private function readNumber() {
+               $data = 0;
+               $shift = 1;
+               for ($i = 0; $i < 16; ++$i) {
+                       $x = ord($this->readByte());
+                       $data += ($x & 0x7f) * $shift;
+                       if ($x & 0x80) break;
+                       $shift <<= 7;
+                       $data += $shift;
+               }
+               return $data;
+       }
+
+       private function readSignedNumber() {
+               $data = $this->readNumber();
+               return ($data & 1 ? -1 : 1) * ($data >> 1);
+       }
+
+       private function readString($length) {
+               $string = substr($this->patch, $this->patchCursor, $length);
+               $this->patchCursor += $length;
+               return $string;
+       }
+
+
+       private $source;
+       private $patch = '';
+       private $target = '';
+       private $metadata = '';
+
+       private $patchCursor = 0;
+       private $outputOffset = 0;
+       private $sourceRelativeOffset = 0;
+       private $targetRelativeOffset = 0;
+
+}

diff --git a/app/Beat/Encoder.php b/app/Beat/Encoder.php
new file mode 100644 (file)
index 0000000..8cbb068
--- /dev/null
+++ b/app/Beat/Encoder.php
@@ -0,0 +1,167 @@
+<?php
+
+namespace App\Beat;
+
+class Encoder {
+
+       public function __construct($source) {
+               $this->source = $source;
+       }
+
+       public function createPatch($target, $metadata = '') {
+               $this->target = $target;
+               $this->patch = '';
+               $this->sourceCursor = 0;
+               $this->targetCursor = 0;
+
+               $this->writeString('BPS1');
+               $this->writeNumber(strlen($this->source));
+               $this->writeNumber(strlen($this->target));
+               $this->writeNumber(strlen($metadata));
+               $this->writeString($metadata);
+
+               $lastKnownChange = 0;
+               $targetCopyPos = 0;
+               while ($this->targetCursor < strlen($this->target)) {
+                       $numUnchanged = 0;
+                       while ($this->sourceLeft($numUnchanged) && $this->sourceEqual($numUnchanged, $numUnchanged, 1)) {
+                               ++$numUnchanged;
+                       }
+                       if ($numUnchanged > 1 || $numUnchanged == (strlen($this->target) - $this->targetCursor)) {
+                               $this->writeNumber(($numUnchanged - 1) << 2);
+                               $this->sourceCursor += $numUnchanged;
+                               $this->targetCursor += $numUnchanged;
+                       }
+
+                       $numChanged = 0;
+                       if ($lastKnownChange > $this->targetCursor) {
+                               $numChanged = $lastKnownChange - $this->targetCursor;
+                       }
+                       while ((!$this->sourceLeft($numChanged) || !$this->sourceEqual($numChanged, $numChanged, 3))
+                               && $this->targetLeft($numChanged)
+                       ) {
+                               ++$numChanged;
+                               if (!$this->sourceLeft($numChanged)) {
+                                       $numChanged = strlen($this->target) - $this->targetCursor;
+                               }
+                       }
+                       $lastKnownChange = $this->targetCursor + $numChanged;
+                       if ($numChanged) {
+                               $rle1Start = $this->targetCursor == 0 ? 1 : 0;
+                               while (true) {
+                                       if ($this->targetEqual($rle1Start - 1, $rle1Start, 4)
+                                               || $this->targetEqual($rle1Start - 2, $rle1Start, 5)
+                                       ) {
+                                               $numChanged = $rle1Start;
+                                               break;
+                                       }
+                                       if ($rle1Start + 3 > $numChanged) {
+                                               break;
+                                       }
+                                       ++$rle1Start;
+                               }
+                               if ($numChanged) {
+                                       $this->writeNumber(($numChanged - 1) << 2 | 1);
+                                       $this->writeString(substr($this->target, $this->targetCursor, $numChanged));
+                                       $this->sourceCursor += $numChanged;
+                                       $this->targetCursor += $numChanged;
+                               }
+                               if ($this->targetEqual(-2, 0, 3)) {
+                                       $rleLen = 0;
+                                       while ($this->targetLeft($rleLen) && $this->targetEqual(0, $rleLen, 2)) {
+                                               $rleLen += 2;
+                                       }
+                                       $this->writeNumber(($rleLen - 1) << 2 | 3);
+                                       $this->writeNumber(($this->targetCursor - $targetCopyPos - 2) << 1);
+                                       $this->sourceCursor += $rleLen;
+                                       $this->targetCursor += $rleLen;
+                                       $targetCopyPos = $this->targetCursor - 2;
+                               } else if ($this->targetEqual(-1, 0, 2)) {
+                                       $rleLen = 0;
+                                       while ($this->targetLeft($rleLen) && $this->targetEqual(0, $rleLen, 1)) {
+                                               $rleLen += 1;
+                                       }
+                                       $this->writeNumber(($rleLen - 1) << 2 | 3);
+                                       $this->writeNumber(($this->targetCursor - $targetCopyPos - 1) << 1);
+                                       $this->sourceCursor += $rleLen;
+                                       $this->targetCursor += $rleLen;
+                                       $targetCopyPos = $this->targetCursor - 1;
+                               }
+                       }
+               }
+
+               $this->write32(crc32($this->source));
+               $this->write32(crc32($this->target));
+               $this->write32(crc32($this->patch));
+
+               return $this->patch;
+       }
+
+
+       private function sourceChar($offset = 0) {
+               return $this->source[$this->sourceCursor + $offset];
+       }
+
+       private function sourceEqual($aOff, $bOff, $len) {
+               $aStr = substr($this->source, $this->sourceCursor + $aOff, $len);
+               $bStr = substr($this->target, $this->targetCursor + $bOff, $len);
+               return $aStr == $bStr;
+       }
+
+       private function sourceLeft($num) {
+               return $this->sourceCursor + $num < strlen($this->source);
+       }
+
+       private function targetChar($offset = 0) {
+               return $this->target[$this->targetCursor + $offset];
+       }
+
+       private function targetEqual($aOff, $bOff, $len) {
+               $aStr = substr($this->target, $this->targetCursor + $aOff, $len);
+               $bStr = substr($this->target, $this->targetCursor + $bOff, $len);
+               return $aStr == $bStr;
+       }
+
+       private function targetLeft($num) {
+               return $this->targetCursor + $num < strlen($this->target);
+       }
+
+
+       private function write32($val) {
+               $this->writeByte($val & 0xFF);
+               $this->writeByte(($val >> 8) & 0xFF);
+               $this->writeByte(($val >> 16) & 0xFF);
+               $this->writeByte(($val >> 24) & 0xFF);
+       }
+
+       private function writeByte($val) {
+               $this->patch .= chr($val);
+       }
+
+       private function writeNumber($val) {
+               $tmpval = $val;
+               for ($i = 0; $i < 16; ++$i) {
+                       $tmpbyte = $tmpval & 0x7f;
+                       $tmpval >>= 7;
+                       if (!$tmpval) {
+                               $this->writeByte($tmpbyte | 0x80);
+                               break;
+                       }
+                       $this->writeByte($tmpbyte);
+                       --$tmpval;
+               }
+       }
+
+       private function writeString($str) {
+               $this->patch .= $str;
+       }
+
+
+       private $source;
+       private $target = '';
+       private $patch = '';
+
+       private $sourceCursor = 0;
+       private $targetCursor = 0;
+
+}

diff --git a/app/Console/Commands/BeatDiffCommand.php b/app/Console/Commands/BeatDiffCommand.php
new file mode 100644 (file)
index 0000000..cf8f9dd
--- /dev/null
+++ b/app/Console/Commands/BeatDiffCommand.php
@@ -0,0 +1,38 @@
+<?php
+
+namespace App\Console\Commands;
+
+use App\Beat\Encoder;
+use Illuminate\Console\Command;
+
+class BeatDiffCommand extends Command
+{
+       /**
+        * The name and signature of the console command.
+        *
+        * @var string
+        */
+       protected $signature = 'beat:diff {source} {target} {patch}';
+
+       /**
+        * The console command description.
+        *
+        * @var string
+        */
+       protected $description = 'Create BPS patch';
+
+       /**
+        * Execute the console command.
+        *
+        * @return int
+        */
+       public function handle()
+       {
+               $source = file_get_contents($this->argument('source'));
+               $target = file_get_contents($this->argument('target'));
+               $encoder = new Encoder($source);
+               $patch = $encoder->createPatch($target);
+               file_put_contents($this->argument('patch'), $patch);
+               return 0;
+       }
+}

diff --git a/app/Console/Commands/BeatPatchCommand.php b/app/Console/Commands/BeatPatchCommand.php
new file mode 100644 (file)
index 0000000..12ad968
--- /dev/null
+++ b/app/Console/Commands/BeatPatchCommand.php
@@ -0,0 +1,38 @@
+<?php
+
+namespace App\Console\Commands;
+
+use App\Beat\Decoder;
+use Illuminate\Console\Command;
+
+class BeatPatchCommand extends Command
+{
+       /**
+        * The name and signature of the console command.
+        *
+        * @var string
+        */
+       protected $signature = 'beat:patch {source} {patch} {target}';
+
+       /**
+        * The console command description.
+        *
+        * @var string
+        */
+       protected $description = 'Apply BPS patch';
+
+       /**
+        * Execute the console command.
+        *
+        * @return int
+        */
+       public function handle()
+       {
+               $source = file_get_contents($this->argument('source'));
+               $patch = file_get_contents($this->argument('patch'));
+               $decoder = new Decoder($source);
+               $target = $decoder->applyPatch($patch);
+               file_put_contents($this->argument('target'), $target);
+               return 0;
+       }
+}