D2S/Item parser in progress. Still need to debug cubemain.txt doc generator output colulmns. Saving code for now

src/D2Functions.php

@@ -75,11 +75,75 @@ function strtobits(string $str): string {
     return $ret;
 }
 
-function swapEndianness($hex) {
+function swapEndianness(string $hex) {
     return implode('', array_reverse(str_split($hex, 2)));
 }
 
 
-function modifyBit(int $n, int $p, bool $b){     
+function setBit(int $n, int $p, bool $b){     
     return ($b ? ($n | (1 << $p)) : ($n & ~(1 << $p)) );  
+}
+
+function getBit(int $b, int $p){
+    return intval(($b & (1 << $p)) != 0);
+}
+
+function checksum($fileData) {
+    $nSignature = 0;
+    foreach($fileData as $byte){            
+        $nSignature = ((($nSignature << 1) | ($nSignature >> 31)) + $byte) & 0xFFFFFFFF;        
+    }
+    return swapEndianness(dechex($nSignature));
+}
+
+/**
+ * Find the position of the Xth occurrence of a substring in a string
+ * @param $haystack
+ * @param $needle
+ * @param $number integer > 0
+ * @return int
+ */
+function strposX($haystack, $needle, $number) {
+    if ($number == 1) {
+        return strpos($haystack, $needle);
+    } elseif ($number > 1) {
+        return strpos($haystack, $needle, strposX($haystack, $needle, $number - 1) + strlen($needle));
+    } else {
+        return error_log('Error: Value for parameter $number is out of range');
+    }
+}
+
+
+function isBit(string $bit): int {
+    return ((int) $bit ? 1 : 0 );
+}
+
+function toBits($input): string {
+    $output = '';
+    if (is_string($input)){
+        foreach(str_split($input) as $i){
+            $output .= str_pad(decbin(ord($i)), 8, 0, STR_PAD_LEFT);
+        }
+        return $output;
+    } else if (is_int($input)){
+        return str_pad(decbin($input), 8, 0, STR_PAD_LEFT);
+    } else if (is_array($input)){
+        foreach ($input as $i) {
+            $output .= tobits($i);
+        }
+        return $output;
+    }    
+    
+}
+
+function print_mem()
+{
+   /* Currently used memory */
+   $mem_usage = memory_get_usage();
+   
+   /* Peak memory usage */
+   $mem_peak = memory_get_peak_usage();
+
+   echo 'The script is now using: <strong>' . round($mem_usage / 1024) . 'KB</strong> of memory.<br>';
+   echo 'Peak usage: <strong>' . round($mem_peak / 1024) . 'KB</strong> of memory.<br><br>';
 }