* * PHP QR Code is distributed under LGPL 3 * Copyright (C) 2010 Dominik Dzienia * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 3 of the License, or any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ class QRrsItem { public $mm; // Bits per symbol public $nn; // Symbols per block (= (1<= $this->nn) { $x -= $this->nn; $x = ($x >> $this->mm) + ($x & $this->nn); } return $x; } //---------------------------------------------------------------------- public static function init_rs_char($symsize, $gfpoly, $fcr, $prim, $nroots, $pad) { // Common code for intializing a Reed-Solomon control block (char or int symbols) // Copyright 2004 Phil Karn, KA9Q // May be used under the terms of the GNU Lesser General Public License (LGPL) $rs = null; // Check parameter ranges if($symsize < 0 || $symsize > 8) return $rs; if($fcr < 0 || $fcr >= (1<<$symsize)) return $rs; if($prim <= 0 || $prim >= (1<<$symsize)) return $rs; if($nroots < 0 || $nroots >= (1<<$symsize)) return $rs; // Can't have more roots than symbol values! if($pad < 0 || $pad >= ((1<<$symsize) -1 - $nroots)) return $rs; // Too much padding $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); // PHP style macro replacement ;) $NN =& $rs->nn; $A0 =& $NN; // Generate Galois field lookup tables $rs->index_of[0] = $A0; // log(zero) = -inf $rs->alpha_to[$A0] = 0; // alpha**-inf = 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){ // field generator polynomial is not primitive! $rs = NULL; return $rs; } /* Form RS code generator polynomial from its roots */ $rs->genpoly = array_fill(0, $nroots+1, 0); $rs->fcr = $fcr; $rs->prim = $prim; $rs->nroots = $nroots; $rs->gfpoly = $gfpoly; /* Find prim-th root of 1, used in decoding */ for($iprim=1;($iprim % $prim) != 0;$iprim += $rs->nn) ; // intentional empty-body loop! $rs->iprim = (int)($iprim / $prim); $rs->genpoly[0] = 1; for ($i = 0,$root=$fcr*$prim; $i < $nroots; $i++, $root += $prim) { $rs->genpoly[$i+1] = 1; // Multiply rs->genpoly[] by @**(root + x) for ($j = $i; $j > 0; $j--) { if ($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] can never be zero $rs->genpoly[0] = $rs->alpha_to[$rs->modnn($rs->index_of[$rs->genpoly[0]] + $root)]; } // convert rs->genpoly[] to index form for quicker encoding for ($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 term is non-zero // This line is unnecessary when GENPOLY[NROOTS] is unity, as it must // always be for the polynomials constructed by init_rs() $feedback = $this->modnn($NN - $GENPOLY[$NROOTS] + $feedback); for($j=1;$j<$NROOTS;$j++) { $parity[$j] ^= $ALPHA_TO[$this->modnn($feedback + $GENPOLY[$NROOTS-$j])]; } } // Shift array_shift($parity); if($feedback != $A0) { array_push($parity, $ALPHA_TO[$this->modnn($feedback + $GENPOLY[0])]); } else { array_push($parity, 0); } } } } //########################################################################## class QRrs { public static $items = array(); //---------------------------------------------------------------------- public static function init_rs($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; } }