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Optimised nibble array re-ordering (halved loop count)

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This commit is contained in:
Dylan K. Taylor 2016-11-20 22:16:35 +00:00
parent 0be8fa4157
commit 2b46794ca2
1 changed files with 13 additions and 18 deletions
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31
src/pocketmine/level/format/generic/GenericChunk.php
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@ -728,30 +728,25 @@ class GenericChunk implements Chunk{
*/
public static final function reorderNibbleArray(string $array) : string{
$result = str_repeat("\x00", 2048);
$i = 0;
for($x = 0; $x < 16; ++$x){
for($z = 0; $z < 16; ++$z){
$xz = (($x << 7) | ($z << 3));
$zx = (($z << 3) | ($x >> 1));
for($y = 0; $y < 16; ++$y){
$inputIndex = (($y << 7) | $zx);
$outputIndex = ($xz | ($y >> 1));
$current = ord($result{$outputIndex});
$byte = ord($array{$inputIndex});
for($y = 0; $y < 8; ++$y){
$j = (($y << 8) | $zx);
$byte = ord($array{$j});
if(($y & 1) === 0){
if(($x & 1) === 0){
$current |= ($byte & 0x0f);
}else{
$current |= (($byte >> 4) & 0x0f);
}
if(($x & 1) === 0){
$current = ($byte & 0x0f);
$byte = ord($array{$j | 0x80});
$current |= ($byte << 4);
}else{
if(($x & 1) === 0){
$current |= (($byte << 4) & 0xf0);
}else{
$current |= ($byte & 0xf0);
}
$current = ($byte >> 4);
$byte = ord($array{$j | 0x80});
$current |= ($byte & 0xf0);
}
$result{$outputIndex} = chr($current);
$result{$i++} = chr($current);
}
}
}