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Added methods for VarLong, limited Binary::readVarInt() to 5-byte numbers

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This commit is contained in:
Dylan K. Taylor 2017-03-08 13:20:10 +00:00
parent adb7df212c
commit 3a044f0154
1 changed files with 243 additions and 11 deletions
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252
src/pocketmine/utils/Binary.php
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@ -336,8 +336,15 @@ class Binary{
return strrev(self::writeLong($value));
}
//TODO: proper varlong support
/**
* Reads a 32-bit zigzag-encoded variable-length integer from the supplied stream.
*
* @param \pocketmine\nbt\NBT|BinaryStream $stream
*
* @return int
*/
public static function readVarInt($stream){
$shift = PHP_INT_SIZE === 8 ? 63 : 31;
$raw = self::readUnsignedVarInt($stream);
@ -345,25 +352,250 @@ class Binary{
return $temp ^ ($raw & (1 << $shift));
}
/**
* Reads a 32-bit variable-length unsigned integer from the supplied stream.
*
* @param \pocketmine\nbt\NBT|BinaryStream $stream
*
* @return int
*/
public static function readUnsignedVarInt($stream){
$value = 0;
$i = 0;
do{
if($i > 63){
throw new \InvalidArgumentException("Varint did not terminate after 10 bytes!");
}
$value |= ((($b = $stream->getByte()) & 0x7f) << $i);
$i += 7;
}while($b & 0x80);
for($i = 0; $i <= 35; $i += 7){
$b = $stream->getByte();
$value |= (($b & 0x7f) << $i);
if(($b & 0x80) === 0){
return $value;
}
}
throw new \InvalidArgumentException("VarInt did not terminate after 5 bytes!");
}
/**
* Writes a 32-bit integer as a zigzag-encoded variable-length integer.
*
* @param int $v
*
* @return string
*/
public static function writeVarInt($v){
return self::writeUnsignedVarInt(($v << 1) ^ ($v >> (PHP_INT_SIZE === 8 ? 63 : 31)));
}
/**
* Writes a 32-bit unsigned integer as a variable-length integer.
* @param int $value
*
* @return string up to 5 bytes
*/
public static function writeUnsignedVarInt($value){
$buf = "";
for($i = 0; $i < 5; ++$i){
if(($value >> 7) !== 0){
$buf .= chr($value | 0x80); //Let chr() take the last byte of this, it's faster than adding another & 0x7f.
}else{
$buf .= chr($value & 0x7f);
return $buf;
}
$value = (($value >> 7) & (PHP_INT_MAX >> 6)); //PHP really needs a logical right-shift operator
}
throw new \InvalidArgumentException("Value too large to be encoded as a VarInt");
}
/**
* Reads a 64-bit zigzag-encoded variable-length integer from the supplied stream.
* @param \pocketmine\nbt\NBT|BinaryStream $stream
*
* @return int
*/
public static function readVarLong($stream){
if(PHP_INT_SIZE === 8){
return self::readVarLong_64($stream);
}else{
return self::readVarLong_32($stream);
}
}
/**
* Legacy BC Math zigzag VarLong reader. Will work on 32-bit or 64-bit, but will be slower than the regular 64-bit method.
* @param \pocketmine\nbt\NBT|BinaryStream $stream
*
* @return string
*/
public static function readVarLong_32($stream){
/** @var string $raw */
$raw = self::readUnsignedVarLong_32($stream);
$result = bcdiv($raw, "2");
if(bcmod($raw, "2") === "1"){
$result = bcsub(bcmul($result, "-1"), "1");
}
return $result;
}
/**
* 64-bit zizgag VarLong reader.
* @param \pocketmine\nbt\NBT|BinaryStream $stream
*
* @return int
*/
public static function readVarLong_64($stream){
$raw = self::readUnsignedVarLong_64($stream);
$temp = ((($raw << 63) >> 63) ^ $raw) >> 1;
return $temp ^ ($raw & (1 << 63));
}
/**
* Reads an unsigned VarLong from the supplied stream.
* @param \pocketmine\nbt\NBT|BinaryStream $stream
*
* @return int|string
*/
public static function readUnsignedVarLong($stream){
if(PHP_INT_SIZE === 8){
return self::readUnsignedVarLong_64($stream);
}else{
return self::readUnsignedVarLong_32($stream);
}
}
/**
* Legacy BC Math unsigned VarLong reader.
* @param \pocketmine\nbt\NBT|BinaryStream $stream
*
* @return string
*/
public static function readUnsignedVarLong_32($stream){
$value = "0";
for($i = 0; $i <= 63; $i += 7){
$b = $stream->getByte();
$value = bcadd($value, bcmul($b & 0x7f, bcpow("2", "$i")));
var_dump($value);
if(($b & 0x80) === 0){
return $value;
}
}
throw new \InvalidArgumentException("VarLong did not terminate after 10 bytes!");
}
/**
* 64-bit unsigned VarLong reader.
* @param \pocketmine\nbt\NBT|BinaryStream $stream
*
* @return int
*/
public static function readUnsignedVarLong_64($stream){
$value = 0;
for($i = 0; $i <= 63; $i += 7){
$b = $stream->getByte();
$value |= (($b & 0x7f) << $i);
var_dump($value);
if(($b & 0x80) === 0){
return $value;
}
}
throw new \InvalidArgumentException("VarLong did not terminate after 10 bytes!");
}
/**
* Writes a 64-bit integer as a variable-length long.
* @param int|string $v
*
* @return string up to 10 bytes
*/
public static function writeVarLong($v){
if(PHP_INT_SIZE === 8){
return self::writeVarLong_64($v);
}else{
return self::writeVarLong_32($v);
}
}
/**
* Legacy BC Math zigzag VarLong encoder.
* @param string $v
*
* @return string
*/
public static function writeVarLong_32($v){
$v = bcmod(bcmul($v, "2"), "18446744073709551616");
if(bccomp($v, "0") == -1){
$v = bcsub(bcmul($v, "-1"), "1");
}
return self::writeUnsignedVarLong_32($v);
}
/**
* 64-bit VarLong encoder.
* @param int $v
*
* @return string
*/
public static function writeVarLong_64($v){
return self::writeUnsignedVarLong_64(($v << 1) ^ ($v >> 63));
}
/**
* Writes a 64-bit integer as a variable-length long
* @param int|string $v
*
* @return string up to 10 bytes
*/
public static function writeUnsignedVarLong($v){
if(PHP_INT_SIZE === 8){
return self::writeUnsignedVarLong_64($v);
}else{
return self::writeUnsignedVarLong_32($v);
}
}
/**
* Legacy BC Math unsigned VarLong encoder.
* @param string $value
*
* @return string
*/
public static function writeUnsignedVarLong_32($value){
$buf = "";
if(bccomp($value, "0") == -1){
$value = bcadd($value, "18446744073709551616");
}
for($i = 0; $i < 10; ++$i){
$byte = (int) bcmod($value, "128");
$value = bcdiv($value, "128");
if($value !== "0"){
$buf .= chr($byte | 0x80);
}else{
$buf .= chr($byte);
return $buf;
}
}
throw new \InvalidArgumentException("Value too large to be encoded as a VarLong");
}
/**
* 64-bit unsigned VarLong encoder.
* @param int $value
*
* @return string
*/
public static function writeUnsignedVarLong_64($value){
$buf = "";
for($i = 0; $i < 10; ++$i){
if(($value >> 7) !== 0){
@ -376,6 +608,6 @@ class Binary{
$value = (($value >> 7) & (PHP_INT_MAX >> 6)); //PHP really needs a logical right-shift operator
}
throw new \InvalidArgumentException("Value too large to be encoded as a varint");
throw new \InvalidArgumentException("Value too large to be encoded as a VarLong");
}
}