<?php

define('CHARSET_HEX', '0123456789abcdef');

define('CHARSET_MODHEX', 'cbdefghijklnrtuv');

define('CHARSET_BASE64', 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=');

function yms_modhex_encode($str)

{

  if ( !preg_match('/^[' . CHARSET_HEX . ']+$/', $str) )

    $str = yms_hex_encode($str);

  return strtr($str, '0123456789abcdef', 'cbdefghijklnrtuv');

}

function yms_modhex_decode($str)

{

  if ( !preg_match('/^[' . CHARSET_MODHEX . ']+$/', $str) )

    return false;

  return strtr($str, 'cbdefghijklnrtuv', '0123456789abcdef');

}

function yms_hex_decode($str)

{

  if ( !preg_match('/^[' . CHARSET_HEX . ']+$/', $str) )

    return false;

  if ( strlen($str) % 2 != 0 )

    return '';

  $return = '';

  for ( $i = 0; $i < strlen($str); $i+=2 )

  {

    $chr = substr($str, $i, 2);

    $return .= chr(intval(hexdec($chr)));

  }

  return $return;

}

function yms_hex_encode($str)

{

  $return = '';

  for ( $i = 0; $i < strlen($str); $i++ )

  {

    $chr = dechex(ord($str{$i}));

    if ( strlen($chr) < 2 )

      $chr = "0$chr";

    $return .= $chr;

  }

  return $return;

}

function yms_tobinary($str)

{

  if ( preg_match('/^[' . CHARSET_HEX . ']+$/', $str) )

  {

    return yms_hex_decode($str);

  }

  else if ( preg_match('/^[' . CHARSET_MODHEX . ']+$/', $str) )

  {

    return yms_hex_decode(yms_modhex_decode($str));

  }

  else if ( preg_match('#^[' . CHARSET_BASE64 . ']+$#', $str) )

  {

    return base64_decode($str);

  }

  return $str;

}

function yms_randbin($len)

{

  $ret = '';

  for ( $i = 0; $i < $len; $i++ )

  {

    $ret .= chr(mt_rand(0, 255));

  }

  return $ret;

}