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- <?php
- class QRrsItem
- {
- public $mm;
- public $nn;
- public $alpha_to = array();
- public $index_of = array();
- public $genpoly = array();
- public $nroots;
- public $fcr;
- public $prim;
- public $iprim;
- public $pad;
- public $gfpoly;
- public function modnn($x)
- {
- while ($this->nn <= $x) {
- $x -= $this->nn;
- $x = ($x >> $this->mm) + ($x & $this->nn);
- }
- return $x;
- }
- static public function init_rs_char($symsize, $gfpoly, $fcr, $prim, $nroots, $pad)
- {
- $rs = NULL;
- if ($symsize < 0 || 8 < $symsize) {
- return $rs;
- }
- if ($fcr < 0 || 1 << $symsize <= $fcr) {
- return $rs;
- }
- if ($prim <= 0 || 1 << $symsize <= $prim) {
- return $rs;
- }
- if ($nroots < 0 || 1 << $symsize <= $nroots) {
- return $rs;
- }
- if ($pad < 0 || (1 << $symsize) - 1 - $nroots <= $pad) {
- return $rs;
- }
- $rs = new QRrsItem();
- $rs->mm = $symsize;
- $rs->nn = (1 << $symsize) - 1;
- $rs->pad = $pad;
- $rs->alpha_to = array_fill(0, $rs->nn + 1, 0);
- $rs->index_of = array_fill(0, $rs->nn + 1, 0);
- $NN = &$rs->nn;
- $A0 = &$NN;
- $rs->index_of[0] = $A0;
- $rs->alpha_to[$A0] = 0;
- $sr = 1;
- for ($i = 0; $i < $rs->nn; $i++) {
- $rs->index_of[$sr] = $i;
- $rs->alpha_to[$i] = $sr;
- $sr <<= 1;
- if ($sr & 1 << $symsize) {
- $sr ^= $gfpoly;
- }
- $sr &= $rs->nn;
- }
- if ($sr != 1) {
- $rs = NULL;
- return $rs;
- }
- $rs->genpoly = array_fill(0, $nroots + 1, 0);
- $rs->fcr = $fcr;
- $rs->prim = $prim;
- $rs->nroots = $nroots;
- $rs->gfpoly = $gfpoly;
- for ($iprim = 1; $iprim % $prim != 0; $iprim += $rs->nn) {
- }
- $rs->iprim = (int) ($iprim / $prim);
- $rs->genpoly[0] = 1;
- $i = 0;
- for ($root = $fcr * $prim; $i < $nroots; $i++, $root += $prim) {
- $rs->genpoly[$i + 1] = 1;
- for ($j = $i; 0 < $j; $j--) {
- if ($rs->genpoly[$j] != 0) {
- $rs->genpoly[$j] = $rs->genpoly[$j - 1] ^ $rs->alpha_to[$rs->modnn($rs->index_of[$rs->genpoly[$j]] + $root)];
- }
- else {
- $rs->genpoly[$j] = $rs->genpoly[$j - 1];
- }
- }
- $rs->genpoly[0] = $rs->alpha_to[$rs->modnn($rs->index_of[$rs->genpoly[0]] + $root)];
- }
- for ($i = 0; $i <= $nroots; $i++) {
- $rs->genpoly[$i] = $rs->index_of[$rs->genpoly[$i]];
- }
- return $rs;
- }
- public function encode_rs_char($data, &$parity)
- {
- $MM = &$this->mm;
- $NN = &$this->nn;
- $ALPHA_TO = &$this->alpha_to;
- $INDEX_OF = &$this->index_of;
- $GENPOLY = &$this->genpoly;
- $NROOTS = &$this->nroots;
- $FCR = &$this->fcr;
- $PRIM = &$this->prim;
- $IPRIM = &$this->iprim;
- $PAD = &$this->pad;
- $A0 = &$NN;
- $parity = array_fill(0, $NROOTS, 0);
- for ($i = 0; $i < $NN - $NROOTS - $PAD; $i++) {
- $feedback = $INDEX_OF[$data[$i] ^ $parity[0]];
- if ($feedback != $A0) {
- $feedback = $this->modnn($NN - $GENPOLY[$NROOTS] + $feedback);
- for ($j = 1; $j < $NROOTS; $j++) {
- $parity[$j] ^= $ALPHA_TO[$this->modnn($feedback + $GENPOLY[$NROOTS - $j])];
- }
- }
- array_shift($parity);
- if ($feedback != $A0) {
- array_push($parity, $ALPHA_TO[$this->modnn($feedback + $GENPOLY[0])]);
- }
- else {
- array_push($parity, 0);
- }
- }
- }
- }
- class QRrs
- {
- static public $items = array();
- static public function init_rs($symsize, $gfpoly, $fcr, $prim, $nroots, $pad)
- {
- foreach (self::$items as $rs) {
- if ($rs->pad != $pad) {
- continue;
- }
- if ($rs->nroots != $nroots) {
- continue;
- }
- if ($rs->mm != $symsize) {
- continue;
- }
- if ($rs->gfpoly != $gfpoly) {
- continue;
- }
- if ($rs->fcr != $fcr) {
- continue;
- }
- if ($rs->prim != $prim) {
- continue;
- }
- return $rs;
- }
- $rs = QRrsItem::init_rs_char($symsize, $gfpoly, $fcr, $prim, $nroots, $pad);
- array_unshift(self::$items, $rs);
- return $rs;
- }
- }
- ?>
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