<?php
/**
 * 大整数类，兼容 gmp、big_int、bcmath
 *
 * PHP支持的大整数计算扩展按照计算速度（由快到慢）排名是 gmp、big_int、bcmath
 * 本类库将会根据系统支持的情况优先选择对应的扩展函数，如果3个大整数扩展都不支持，将使用 PHP 脚本来模拟大整数运算，并不影响输出，只是运算速度会较这3种扩展慢一些
 *
 * 本类库修改自 PHPRPC 中 BigInt 相关函数
 *
 * @author     呼吸二氧化碳 <jonwang@myqee.com>
 * @category   MyQEE
 * @package    System
 * @subpackage Core
 * @copyright  Copyright (c) 2008-2016 myqee.com
 * @copyright  http://www.phprpc.org/
 * @see        http://www.phprpc.org/
 * @license    http://www.myqee.com/license.html
 */
class Core_BigInt
{
    public static function dec2num($dec)
    {
        switch (BigInt::support())
        {
            case 'gmp':
                return gmp_init($dec);

            case 'big_int':
                return bi_from_str($dec);

            case 'bcmath':
                return $dec;

            case '':
            default:
                return BigInt::_dec2num($dec);
        }
    }

    public static function num2dec($num)
    {
        switch (BigInt::support())
        {
            case 'gmp':
                return gmp_strval($num);

            case 'big_int':
                return bi_to_str($num);

            case 'bcmath':
                return $num;

            case '':
            default:
                return BigInt::_num2dec($num);
        }
    }

    public static function str2num($str)
    {
        switch (BigInt::support())
        {
            case 'gmp':
                return gmp_init("0x".bin2hex($str));

            case 'big_int':
                return bi_from_str(bin2hex($str), 16);

            case 'bcmath':
                bcscale(0);
                $len = strlen($str);
                $result = '0';
                $m = '1';
                for ($i = 0; $i < $len; $i++)
                {
                    $result = bcadd(bcmul($m, ord($str{$len - $i - 1})), $result);
                    $m = bcmul($m, '256');
                }
                return $result;

            case '':
            default:
                return BigInt::_str2num($str);
        }
    }

    public static function num2str($num)
    {
        switch (BigInt::support())
        {
            case 'gmp':

                $str = gmp_strval($num, 16);
                $len = strlen($str);
                if ($len % 2 == 1)
                {
                    $str = '0'.$str;
                }
                return pack("H*", $str);

            case 'big_int':
                $str = bi_to_str($num, 16);
                $len = strlen($str);
                if ($len % 2 == 1)
                {
                    $str = '0'.$str;
                }
                return pack("H*", $str);

            case 'bcmath':

                bcscale(0);
                $str = "";
                while (bccomp($num, '0') == 1)
                {
                    $str = chr(bcmod($num, '256')) . $str;
                    $num = bcdiv($num, '256');
                }
                return $str;

            case '':
            default:
                return BigInt::_num2str($num);
        }
    }


    public static function random($n, $s)
    {
        switch (BigInt::support())
        {
            case 'gmp':

                    $result = gmp_init(0);
                for ($i = 0; $i < $n; $i++)
                {
                    if (mt_rand(0, 1))
                    {
                        gmp_setbit($result, $i);
                    }
                }
                if ($s)
                {
                    gmp_setbit($result, $n - 1);
                }
                return $result;

            case 'big_int':
                $result = bi_rand($n);
                if ($s)
                {
                    $result = bi_set_bit($result, $n - 1);
                }
                return $result;

            case 'bcmath':

                bcscale(0);
                $t = BigInt::bcpow(2, $n);
                if ($s == 1)
                {
                    $m = bcdiv($t, 2);
                    $t = bcsub($m, 1);
                }
                else
                {
                    $m = 0;
                    $t = bcsub($t, 1);
                }
                $l = strlen($t);
                $n = (int) ($l / 9) + 1;
                $r = '';
                while($n)
                {
                    $r .= substr('000000000' . mt_rand(0, 999999999), -9);
                    --$n;
                }
                $r = substr($r, 0, $l);
                while (bccomp($r, $t) == 1) $r = substr($r, 1, $l) . mt_rand(0, 9);
                return bcadd($r, $m);

            case '':
            default:
                return BigInt::_random($n, $s);
        }
    }

    public static function powmod($x, $y, $m)
    {
        switch (BigInt::support())
        {
            case 'gmp':
                return gmp_powm($x, $y, $m);

            case 'big_int':
                return bi_powmod($x, $y, $m);

            case 'bcmath':
                return bcpowmod($x, $y, $m);

            case '':
            default:
                return BigInt::_powmod($x, $y, $m);
        }
    }

    /**
     * 返回系统支持的类型
     *
     * 将返回 `gmp` | `big_int` | `bcmath` | `default`
     *
     * @return string
     */
    protected static function support()
    {
        static $support = null;

        if ($support)return $support;
        
        if (extension_loaded('gmp'))
        {
            $support = 'gmp';
        }
        else if (extension_loaded('big_int'))
        {
            $support = 'big_int';
        }
        else if (extension_loaded('bcmath'))
        {
            $support = 'bcmath';

            if (!function_exists('bcpowmod'))
            {
                function bcpowmod($x, $y, $modulus, $scale = 0)
                {
                    $t = '1';
                    while (bccomp($y, '0'))
                    {
                        if (bccomp(bcmod($y, '2'), '0'))
                        {
                            $t = bcmod(bcmul($t, $x), $modulus);
                            $y = bcsub($y, '1');
                        }

                        $x = bcmod(bcmul($x, $x), $modulus);
                        $y = bcdiv($y, '2');
                    }
                    return $t;
                }
            }
        }
        else
        {
            $support = 'default';
        }

        return $support;
    }

    protected static function bcpow($b, $e)
    {
        if ($b == 2)
        {
            $a[96]   = '79228162514264337593543950336';
            $a[128]  = '340282366920938463463374607431768211456';
            $a[160]  = '1461501637330902918203684832716283019655932542976';
            $a[192]  = '6277101735386680763835789423207666416102355444464034512896';
            $a[256]  = '115792089237316195423570985008687907853269984665640564039457584007913129639936';
            $a[512]  = '13407807929942597099574024998205846127479365820592393377723561443721764030073546976801874298166903427690031858186486050853753882811946569946433649006084096';
            $a[768]  = '1552518092300708935148979488462502555256886017116696611139052038026050952686376886330878408828646477950487730697131073206171580044114814391444287275041181139204454976020849905550265285631598444825262999193716468750892846853816057856';
            $a[1024] = '179769313486231590772930519078902473361797697894230657273430081157732675805500963132708477322407536021120113879871393357658789768814416622492847430639474124377767893424865485276302219601246094119453082952085005768838150682342462881473913110540827237163350510684586298239947245938479716304835356329624224137216';
            $a[1356] = '1572802244866018108182967249994981337399178505432223228293716677435703277129801955281491139254988030713172834803458459525011536776047399098682525970017006610187370020027540826048617586909475175880278263391147764612823746132583281588112028234096933800670620569966257212339315820309710495898777306979706509398705741430192541287726011814541176060679505247297118998085067003005943214893171428950699778511718055936';
            $a[2048] = '32317006071311007300714876688669951960444102669715484032130345427524655138867890893197201411522913463688717960921898019494119559150490921095088152386448283120630877367300996091750197750389652106796057638384067568276792218642619756161838094338476170470581645852036305042887575891541065808607552399123930385521914333389668342420684974786564569494856176035326322058077805659331026192708460314150258592864177116725943603718461857357598351152301645904403697613233287231227125684710820209725157101726931323469678542580656697935045997268352998638215525166389437335543602135433229604645318478604952148193555853611059596230656';
            $a[3072] = '5809605995369958062859502533304574370686975176362895236661486152287203730997110225737336044533118407251326157754980517443990529594540047121662885672187032401032111639706440498844049850989051627200244765807041812394729680540024104827976584369381522292361208779044769892743225751738076979568811309579125511333093243519553784816306381580161860200247492568448150242515304449577187604136428738580990172551573934146255830366405915000869643732053218566832545291107903722831634138599586406690325959725187447169059540805012310209639011750748760017095360734234945757416272994856013308616958529958304677637019181594088528345061285863898271763457294883546638879554311615446446330199254382340016292057090751175533888161918987295591531536698701292267685465517437915790823154844634780260102891718032495396075041899485513811126977307478969074857043710716150121315922024556759241239013152919710956468406379442914941614357107914462567329693696';
            $a[4096] = '1044388881413152506691752710716624382579964249047383780384233483283953907971557456848826811934997558340890106714439262837987573438185793607263236087851365277945956976543709998340361590134383718314428070011855946226376318839397712745672334684344586617496807908705803704071284048740118609114467977783598029006686938976881787785946905630190260940599579453432823469303026696443059025015972399867714215541693835559885291486318237914434496734087811872639496475100189041349008417061675093668333850551032972088269550769983616369411933015213796825837188091833656751221318492846368125550225998300412344784862595674492194617023806505913245610825731835380087608622102834270197698202313169017678006675195485079921636419370285375124784014907159135459982790513399611551794271106831134090584272884279791554849782954323534517065223269061394905987693002122963395687782878948440616007412945674919823050571642377154816321380631045902916136926708342856440730447899971901781465763473223850267253059899795996090799469201774624817718449867455659250178329070473119433165550807568221846571746373296884912819520317457002440926616910874148385078411929804522981857338977648103126085903001302413467189726673216491511131602920781738033436090243804708340403154190336';
            $a[8192] = '1090748135619415929462984244733782862448264161996232692431832786189721331849119295216264234525201987223957291796157025273109870820177184063610979765077554799078906298842192989538609825228048205159696851613591638196771886542609324560121290553901886301017900252535799917200010079600026535836800905297805880952350501630195475653911005312364560014847426035293551245843928918752768696279344088055617515694349945406677825140814900616105920256438504578013326493565836047242407382442812245131517757519164899226365743722432277368075027627883045206501792761700945699168497257879683851737049996900961120515655050115561271491492515342105748966629547032786321505730828430221664970324396138635251626409516168005427623435996308921691446181187406395310665404885739434832877428167407495370993511868756359970390117021823616749458620969857006263612082706715408157066575137281027022310927564910276759160520878304632411049364568754920967322982459184763427383790272448438018526977764941072715611580434690827459339991961414242741410599117426060556483763756314527611362658628383368621157993638020878537675545336789915694234433955666315070087213535470255670312004130725495834508357439653828936077080978550578912967907352780054935621561090795845172954115972927479877527738560008204118558930004777748727761853813510493840581861598652211605960308356405941821189714037868726219481498727603653616298856174822413033485438785324024751419417183012281078209729303537372804574372095228703622776363945290869806258422355148507571039619387449629866808188769662815778153079393179093143648340761738581819563002994422790754955061288818308430079648693232179158765918035565216157115402992120276155607873107937477466841528362987708699450152031231862594203085693838944657061346236704234026821102958954951197087076546186622796294536451620756509351018906023773821539532776208676978589731966330308893304665169436185078350641568336944530051437491311298834367265238595404904273455928723949525227184617404367854754610474377019768025576605881038077270707717942221977090385438585844095492116099852538903974655703943973086090930596963360767529964938414598185705963754561497355827813623833288906309004288017321424808663962671333528009232758350873059614118723781422101460198615747386855096896089189180441339558524822867541113212638793675567650340362970031930023397828465318547238244232028015189689660418822976000815437610652254270163595650875433851147123214227266605403581781469090806576468950587661997186505665475715792896';
            return (isset($a[$e]) ? $a[$e] : bcpow(2, $e));
        }
        return bcpow($b, $e);
    }

    protected static function zerofill($str, $num)
    {
        return str_pad($str, $num, '0', STR_PAD_LEFT);
    }

    protected static function mul($a, $b)
    {
        $n = count($a);
        $m = count($b);
        $nm = $n + $m;
        $c = array_fill(0, $nm, 0);
        for ($i = 0; $i < $n; $i++)
        {
            for ($j = 0; $j < $m; $j++)
            {
                $c[$i + $j]     += $a[$i] * $b[$j];
                $c[$i + $j + 1] += ($c[$i + $j] >> 15) & 0x7fff;
                $c[$i + $j]     &= 0x7fff;
            }
        }
        return $c;
    }

    protected static function div($a, $b, $is_mod = 0)
    {
        $n = count($a);
        $m = count($b);
        $c = array();
        $d = floor(0x8000 / ($b[$m - 1] + 1));
        $a = BigInt::mul($a, array($d));
        $b = BigInt::mul($b, array($d));

        for ($j = $n - $m; $j >= 0; $j--)
        {
            $tmp = $a[$j + $m] * 0x8000 + $a[$j + $m - 1];
            $rr = $tmp % $b[$m - 1];
            $qq = round(($tmp - $rr) / $b[$m - 1]);
            if (($qq == 0x8000) || (($m > 1) && ($qq * $b[$m - 2] > 0x8000 * $rr + $a[$j + $m - 2])))
            {
                $qq--;
                $rr += $b[$m - 1];
                if (($rr < 0x8000) && ($qq * $b[$m - 2] > 0x8000 * $rr + $a[$j + $m - 2])) $qq--;
            }
            for ($i = 0; $i < $m; $i++)
            {
                $tmp = $i + $j;
                $a[$tmp] -= $b[$i] * $qq;
                $a[$tmp + 1] += floor($a[$tmp] / 0x8000);
                $a[$tmp] &= 0x7fff;
            }
            $c[$j] = $qq;
            if ($a[$tmp + 1] < 0)
            {
                $c[$j]--;
                for ($i = 0; $i < $m; $i++)
                {
                    $tmp = $i + $j;
                    $a[$tmp] += $b[$i];
                    if ($a[$tmp] > 0x7fff)
                    {
                        $a[$tmp + 1]++;
                        $a[$tmp] &= 0x7fff;
                    }
                }
            }
        }
        if (!$is_mod) return $c;
        $b = array();
        for ($i = 0; $i < $m; $i++) $b[$i] = $a[$i];

        return BigInt::div($b, array($d));
    }

    protected static function _dec2num($dec)
    {
        $n = strlen($dec);
        $a = array(0);
        $n += 4 - ($n % 4);
        $dec = BigInt::zerofill($dec, $n);
        $n >>= 2;
        for ($i = 0; $i < $n; $i++)
        {
            $a = BigInt::mul($a, array(10000));
            $a[0] += (int)substr($dec, 4 * $i, 4);
            $m = count($a);
            $j = 0;
            $a[$m] = 0;
            while ($j < $m && $a[$j] > 0x7fff)
            {
                $a[$j++] &= 0x7fff;
                $a[$j]++;
            }
            while ((count($a) > 1) && (!$a[count($a) - 1])) array_pop($a);
        }
        return $a;
    }

    protected static function _num2dec($num)
    {
        $n = count($num) << 1;
        $b = array();
        for ($i = 0; $i < $n; $i++)
        {
            $tmp   = BigInt::div($num, array(10000), 1);
            $b[$i] = BigInt::zerofill($tmp[0], 4);
            $num   = BigInt::div($num, array(10000));
        }
        while ((count($b) > 1) && !(int)$b[count($b) - 1]) array_pop($b);
        $n     = count($b) - 1;
        $b[$n] = (int)$b[$n];
        $b     = join('', array_reverse($b));
        return $b;
    }

    protected static function _str2num($str)
    {
        $n = strlen($str);
        $n += 15 - ($n % 15);
        $str = str_pad($str, $n, chr(0), STR_PAD_LEFT);
        $j = 0;
        $result = array();
        for ($i = 0; $i < $n; $i++)
        {
            $result[$j++] = (ord($str{$i++}) << 7) | (ord($str{$i}) >> 1);
            $result[$j++] = ((ord($str{$i++}) & 0x01) << 14) | (ord($str{$i++}) << 6) | (ord($str{$i}) >> 2);
            $result[$j++] = ((ord($str{$i++}) & 0x03) << 13) | (ord($str{$i++}) << 5) | (ord($str{$i}) >> 3);
            $result[$j++] = ((ord($str{$i++}) & 0x07) << 12) | (ord($str{$i++}) << 4) | (ord($str{$i}) >> 4);
            $result[$j++] = ((ord($str{$i++}) & 0x0f) << 11) | (ord($str{$i++}) << 3) | (ord($str{$i}) >> 5);
            $result[$j++] = ((ord($str{$i++}) & 0x1f) << 10) | (ord($str{$i++}) << 2) | (ord($str{$i}) >> 6);
            $result[$j++] = ((ord($str{$i++}) & 0x3f) << 9)  | (ord($str{$i++}) << 1) | (ord($str{$i}) >> 7);
            $result[$j++] = ((ord($str{$i++}) & 0x7f) << 8)  | ord($str{$i});
        }
        $result = array_reverse($result);
        $i = count($result) - 1;
        while ($result[$i] == 0)
        {
            array_pop($result);
            $i--;
        }
        return $result;
    }


    protected static function _num2str($num)
    {
        ksort($num, SORT_NUMERIC);
        $n = count($num);
        $n += 8 - ($n % 8);
        $num = array_reverse(array_pad($num, $n, 0));
        $s = '';
        for ($i = 0; $i < $n; $i++)
        {
            $s .= chr($num[$i] >> 7);
            $s .= chr((($num[$i++] & 0x7f) << 1) | ($num[$i] >> 14));
            $s .= chr(($num[$i] >> 6) & 0xff);
            $s .= chr((($num[$i++] & 0x3f) << 2) | ($num[$i] >> 13));
            $s .= chr(($num[$i] >> 5) & 0xff);
            $s .= chr((($num[$i++] & 0x1f) << 3) | ($num[$i] >> 12));
            $s .= chr(($num[$i] >> 4) & 0xff);
            $s .= chr((($num[$i++] & 0x0f) << 4) | ($num[$i] >> 11));
            $s .= chr(($num[$i] >> 3) & 0xff);
            $s .= chr((($num[$i++] & 0x07) << 5) | ($num[$i] >> 10));
            $s .= chr(($num[$i] >> 2) & 0xff);
            $s .= chr((($num[$i++] & 0x03) << 6) | ($num[$i] >> 9));
            $s .= chr(($num[$i] >> 1) & 0xff);
            $s .= chr((($num[$i++] & 0x01) << 7) | ($num[$i] >> 8));
            $s .= chr($num[$i] & 0xff);
        }

        return ltrim($s, chr(0));
    }

    protected static function _random($n, $s)
    {
        $lowBitMasks = array
        (
            0x0000, 0x0001, 0x0003, 0x0007,
            0x000f, 0x001f, 0x003f, 0x007f,
            0x00ff, 0x01ff, 0x03ff, 0x07ff,
            0x0fff, 0x1fff, 0x3fff
        );

        $r = $n % 15;
        $q = floor($n / 15);
        $result = array();
        for ($i = 0; $i < $q; $i++)
        {
            $result[$i] = mt_rand(0, 0x7fff);
        }

        if ($r != 0)
        {
            $result[$q] = mt_rand(0, $lowBitMasks[$r]);
            if ($s)
            {
                $result[$q] |= 1 << ($r - 1);
            }
        }
        else if ($s)
        {
            $result[$q - 1] |= 0x4000;
        }
        return $result;
    }

    protected static function _powmod($x, $y, $m)
    {
        $n = count($y);
        $p = array(1);
        for ($i = 0; $i < $n - 1; $i++)
        {
            $tmp = $y[$i];
            for ($j = 0; $j < 0xf; $j++)
            {
                if ($tmp & 1) $p = BigInt::div(BigInt::mul($p, $x), $m, 1);
                $tmp >>= 1;
                $x = BigInt::div(BigInt::mul($x, $x), $m, 1);
            }
        }
        $tmp = $y[$i];
        while ($tmp)
        {
            if ($tmp & 1) $p = BigInt::div(BigInt::mul($p, $x), $m, 1);
            $tmp >>= 1;
            $x = BigInt::div(BigInt::mul($x, $x), $m, 1);
        }

        return $p;
    }
}