Gera código de barras PHP

<?php
function geraCodigoBarra($numero){
$fino = 1;
$largo = 3;
$altura = 50;

$barcodes[0] = '00110';
$barcodes[1] = '10001';
$barcodes[2] = '01001';
$barcodes[3] = '11000';
$barcodes[4] = '00101';
$barcodes[5] = '10100';
$barcodes[6] = '01100';
$barcodes[7] = '00011';
$barcodes[8] = '10010';
$barcodes[9] = '01010';

for($f1 = 9; $f1 >= 0; $f1--){
for($f2 = 9; $f2 >= 0; $f2--){
$f = ($f1*10)+$f2;
$texto = '';
for($i = 1; $i < 6; $i++){
$texto .= substr($barcodes[$f1], ($i-1), 1).substr($barcodes[$f2] ,($i-1), 1);
}
$barcodes[$f] = $texto;
}
}

echo '<img src="imagens/p.gif" width="'.$fino.'" height="'.$altura.'" border="0" />';
echo '<img src="imagens/b.gif" width="'.$fino.'" height="'.$altura.'" border="0" />';
echo '<img src="imagens/p.gif" width="'.$fino.'" height="'.$altura.'" border="0" />';
echo '<img src="imagens/b.gif" width="'.$fino.'" height="'.$altura.'" border="0" />';

echo '<img ';

$texto = $numero;

if((strlen($texto) % 2) <> 0){
$texto = '0'.$texto;
}

while(strlen($texto) > 0){
$i = round(substr($texto, 0, 2));
$texto = substr($texto, strlen($texto)-(strlen($texto)-2), (strlen($texto)-2));

if(isset($barcodes[$i])){
$f = $barcodes[$i];
}

for($i = 1; $i < 11; $i+=2){
if(substr($f, ($i-1), 1) == '0'){
$f1 = $fino ;
}else{
$f1 = $largo ;
}

echo 'src="imagens/p.gif" width="'.$f1.'" height="'.$altura.'" border="0">';
echo '<img ';

if(substr($f, $i, 1) == '0'){
$f2 = $fino ;
}else{
$f2 = $largo ;
}

echo 'src="imagens/b.gif" width="'.$f2.'" height="'.$altura.'" border="0">';
echo '<img ';
}
}
echo 'src="imagens/p.gif" width="'.$largo.'" height="'.$altura.'" border="0" />';
echo '<img src="imagens/b.gif" width="'.$fino.'" height="'.$altura.'" border="0" />';
echo '<img src="imagens/p.gif" width="1" height="'.$altura.'" border="0" />';
}

geraCodigoBarra('0123456789');
?>