php中big5转utf8乱码怎么办？

<?php

//生成big5-unicode 编码文件

function loadBig5(){

    $fp = fopen( './big5-unicode.txt', 'r' );

    $big5_unicode_arr = array();

    while($one_line = fgets($fp)) {

        $one_line_arr = explode("\t",$one_line);

        $big5 = hexdec(trim($one_line_arr[0]));

        $unicode = trim($one_line_arr[1]);

        if(strpos($unicode,',')) {

            $unicode = ltrim(explode(',',$unicode)[0],'<');

        }

        $big5_unicode_arr[$big5] = hexdec($unicode);

    }

    return $big5_unicode_arr;

}

//追加形式写入文件

function putContent($content) {

    static $fp;

    if(!isset($fp)) {

        $fp = fopen( './big5-unicode-new.tab', 'a+' );

    }

    fwrite($fp,$content);

}

//生成tab文件

function writebig5UnicodeFile() {

    $big5_unicode_arr = loadBig5();

    $big5_unicod_content = array();

    $min = 2000;

    $max = 0;

    $max_unicode = 0;

    foreach($big5_unicode_arr as $big5 => $unicode) {

        $h = floor($big5/256);

        $l = $big5%256;

        $index = ($h-135)*256*3+$l*3;

        if($index<$min) {

            $min = $index;

        }

        if($max<$index) {

            $max = $index;

        }

        if($unicode>$max_unicode) {

            $max_unicode = $unicode;

        }

        $h_1 = floor($unicode/65536);

        $h_2 = floor($unicode/256);

        $h_3 = $unicode%256;

        $big5_unicod_content[$index] = chr($h_1).chr($h_2).chr($h_3);

    }

    for($i=0;$i<=$max;$i=$i+3) {

        if(!isset($big5_unicod_content[$i])) {

            $big5_unicod_content[$i] = chr(0).chr(0).chr(0);

        }

    }

    for($i=0;$i<=$max;$i=$i+3) {

        if(strlen($big5_unicod_content[$i]) == 3) {

            putContent($big5_unicod_content[$i]);

        }else{

            die('error');

        }

    }

}

//测试编辑结果

function testCode() {

    $content = file_get_contents( './temlate_2.html');

    echo b2u($content);

}

//打印出编码库文字

function printfCode() {

    $fp = fopen( './big5-unicode-new.tab', 'r' );

    $len = filesize('./big5-unicode-new.tab');

    $x = 0;

    $outstr = array();

    //     fseek( $fp, 21000 - 900 + 42*3);

    for($i=$x=0;$i<$len;$i=$i+3) {

        $uni = fread( $fp, 3 );

        $codenum = ord($uni[0])*65536 + ord($uni[1])*256 + ord($uni[2]);

        if($codenum == 0) {

            $outstr[$x++] = ' ';

        }elseif( $codenum < 0x80 ) {

            $outstr[$x++] = chr($codenum);

        }elseif($codenum < 0x800) {

            $outstr[$x++] = chr( 192 + $codenum / 64 );

            $outstr[$x++] = chr( 128 + $codenum % 64 );

        }elseif($codenum < 0x10000){

            $outstr[$x++] = chr( 224 + floor($codenum / 4096 ));

            $codenum = $codenum%4096;

            $outstr[$x++] = chr( 128 + floor($codenum / 64 ));

            $outstr[$x++] = chr( 128 + ($codenum % 64) );

        }else{

            $outstr[$x++] = chr( 240 + floor($codenum / 262144 ));

            $codenum = $codenum%262144;

            $outstr[$x++] = chr( 128 + floor($codenum / 4096 ));

            $codenum = $codenum%4096;

            $outstr[$x++] = chr( 128 + ($codenum / 64) );

            $outstr[$x++] = chr( 128 + ($codenum % 64) );

        }

    }

    echo join( '', $outstr);

}

//big5 转 utf-8

function b2u( $instr ) {

    $fp = fopen( './big5-unicode-new.tab', 'r' );

    $len = strlen($instr);

    $outstr = '';

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

        $h = ord($instr[$i]);

        if( $h >= 135 ) {

            $l = ord($instr[$i+1]);

            fseek( $fp, ($h-135)*256*3+$l*3 );

            $uni = fread( $fp, 3 );

            $codenum = ord($uni[0])*65536 + ord($uni[1])*256 + ord($uni[2]);

            if($codenum == 0) {

                $outstr[$x++] = ' ';

            }elseif( $codenum < 0x80 ) {

                $outstr[$x++] = chr($codenum);

            }elseif($codenum < 0x800) {

                $outstr[$x++] = chr( 192 + $codenum / 64 );

                $outstr[$x++] = chr( 128 + $codenum % 64 );

            }elseif($codenum < 0x10000){

                $outstr[$x++] = chr( 224 + floor($codenum / 4096 ));

                $codenum = $codenum%4096;

                $outstr[$x++] = chr( 128 + floor($codenum / 64 ));

                $outstr[$x++] = chr( 128 + ($codenum % 64) );

            }else{

                $outstr[$x++] = chr( 240 + floor($codenum / 262144 ));

                $codenum = $codenum%262144;

                $outstr[$x++] = chr( 128 + floor($codenum / 4096 ));

                $codenum = $codenum%4096;

                $outstr[$x++] = chr( 128 + ($codenum / 64) );

                $outstr[$x++] = chr( 128 + ($codenum % 64) );

            }

            $i++;

        }

        else

            $outstr[$x++] = $instr[$i];

    }

    fclose($fp);

    if( $instr != '' )

        return join( '', $outstr);

}