php memory allocation

index.php

<?php

class MemoryManager {
  private $_buffer;
  private $_allocation;
  private $_numBytes;
  private $_currentNumBytes;
  
  function __construct(&$buffer, $numBytes) {
    $buffer = array_fill(0, $numBytes, NULL);
    $this->_buffer = $buffer;
    $this->_numBytes = $numBytes;
    $this->_currentNumBytes = 0;
    $this->_allocation = array_fill(0, $numBytes, NULL);
  }

  /**
   * return pointer
   */
  function &alloc($size) {
    if ($this->_currentNumBytes+$size >= $this->_numBytes) {
      // throw error
      echo "Full memory";
      $null_var = NULL;
      return $null_var;
    }

    // search free position
    $acc = 0;
    $flag = false;
    for ($i=0; $i < $this->_numBytes; $i++) {
      if (is_null($this->_allocation[$i])) $acc++;
      else $acc = 0;
      if ($acc >= $size) {
        $flag = true;
        break;
      }
    }

    // allocate memory
    if ($flag) {
      $this->_currentNumBytes += $size;

      $memoryDirection = $i - ($size-1);
      for ($j=0; $j < $size; $j++) {
        $this->_allocation[$memoryDirection+$j] = -1;
      }
      $this->_allocation[$memoryDirection] = $size;
      return $memoryDirection;
    }
    // throw error
    echo "Limit error";
    $null_var = NULL;
    return $null_var;
  }

  function free($ptr) {
    if ($this->_allocation[$ptr] == -1) {
      // throw error
      echo "Segmentation fault";
      return;
    }
    for ($i=0; $i < $this->_allocation[$ptr]; $i++) { 
      $this->_buffer[$ptr+$i] = NULL;
    }
  }

  function assign($ptr, $value) {
    $this->_buffer[$ptr] = $value;
  }

  function next(&$ptr) {
    return $ptr+1; // move direction memory a block
  }

  function getValue($ptr) {
    return $this->_buffer[$ptr];
  }
}



$NewBuffer = NULL;
$New = new MemoryManager($NewBuffer, 25);

$pointer = $New->alloc(3);
$New->assign($pointer, 4); // *pointer = 4
$New->assign($pointer+1, 7); // *(pointer+1) = 7
$New->assign($pointer+2, 2); // *(pointer+2) = 2

echo "The pointer value is: ".$New->getValue($pointer);
echo "\nThe ++pointer value is: ".$New->getValue($pointer+1);
echo "\n";

$New->free($pointer);
echo "The pointer value is: ".(is_null($New->getValue($pointer)) ? 'NULL' : $New->getValue($pointer));
echo "\n";