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-rw-r--r--genqrcode/tests/rscode.c274
1 files changed, 274 insertions, 0 deletions
diff --git a/genqrcode/tests/rscode.c b/genqrcode/tests/rscode.c
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+++ b/genqrcode/tests/rscode.c
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+/*
+ * qrencode - QR Code encoder
+ *
+ * Reed solomon encoder. This code is taken from Phil Karn's libfec then
+ * editted and packed into a pair of .c and .h files.
+ *
+ * Copyright (C) 2002, 2003, 2004, 2006 Phil Karn, KA9Q
+ * (libfec is released under the GNU Lesser General Public License.)
+ *
+ * Copyright (C) 2006-2011 Kentaro Fukuchi <kentaro@fukuchi.org>
+ *
+ * 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 2.1 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
+ */
+
+#if HAVE_CONFIG_H
+# include "config.h"
+#endif
+#include <stdlib.h>
+#include <string.h>
+
+#include "rscode.h"
+
+/* Stuff specific to the 8-bit symbol version of the general purpose RS codecs
+ *
+ */
+typedef unsigned char data_t;
+
+
+/**
+ * Reed-Solomon codec control block
+ */
+struct _RS {
+ int mm; /* Bits per symbol */
+ int nn; /* Symbols per block (= (1<<mm)-1) */
+ data_t *alpha_to; /* log lookup table */
+ data_t *index_of; /* Antilog lookup table */
+ data_t *genpoly; /* Generator polynomial */
+ int nroots; /* Number of generator roots = number of parity symbols */
+ int fcr; /* First consecutive root, index form */
+ int prim; /* Primitive element, index form */
+ int iprim; /* prim-th root of 1, index form */
+ int pad; /* Padding bytes in shortened block */
+ int gfpoly;
+};
+
+static inline int modnn(RS *rs, int x){
+ while (x >= rs->nn) {
+ x -= rs->nn;
+ x = (x >> rs->mm) + (x & rs->nn);
+ }
+ return x;
+}
+
+
+#define MODNN(x) modnn(rs,x)
+
+#define MM (rs->mm)
+#define NN (rs->nn)
+#define ALPHA_TO (rs->alpha_to)
+#define INDEX_OF (rs->index_of)
+#define GENPOLY (rs->genpoly)
+#define NROOTS (rs->nroots)
+#define FCR (rs->fcr)
+#define PRIM (rs->prim)
+#define IPRIM (rs->iprim)
+#define PAD (rs->pad)
+#define A0 (NN)
+
+
+/* Initialize a Reed-Solomon codec
+ * symsize = symbol size, bits
+ * gfpoly = Field generator polynomial coefficients
+ * fcr = first root of RS code generator polynomial, index form
+ * prim = primitive element to generate polynomial roots
+ * nroots = RS code generator polynomial degree (number of roots)
+ * pad = padding bytes at front of shortened block
+ */
+static RS *init_rs_char(int symsize, int gfpoly, int fcr, int prim, int nroots, int pad)
+{
+ RS *rs;
+
+
+/* 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)
+ */
+//#undef NULL
+//#define NULL ((void *)0)
+
+ int i, j, sr,root,iprim;
+
+ rs = NULL;
+ /* Check parameter ranges */
+ if(symsize < 0 || symsize > (int)(8*sizeof(data_t))){
+ goto done;
+ }
+
+ if(fcr < 0 || fcr >= (1<<symsize))
+ goto done;
+ if(prim <= 0 || prim >= (1<<symsize))
+ goto done;
+ if(nroots < 0 || nroots >= (1<<symsize))
+ goto done; /* Can't have more roots than symbol values! */
+ if(pad < 0 || pad >= ((1<<symsize) -1 - nroots))
+ goto done; /* Too much padding */
+
+ rs = (RS *)calloc(1,sizeof(RS));
+ if(rs == NULL)
+ goto done;
+
+ rs->mm = symsize;
+ rs->nn = (1<<symsize)-1;
+ rs->pad = pad;
+
+ rs->alpha_to = (data_t *)malloc(sizeof(data_t)*(rs->nn+1));
+ if(rs->alpha_to == NULL){
+ free(rs);
+ rs = NULL;
+ goto done;
+ }
+ rs->index_of = (data_t *)malloc(sizeof(data_t)*(rs->nn+1));
+ if(rs->index_of == NULL){
+ free(rs->alpha_to);
+ free(rs);
+ rs = NULL;
+ goto done;
+ }
+
+ /* 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! */
+ free(rs->alpha_to);
+ free(rs->index_of);
+ free(rs);
+ rs = NULL;
+ goto done;
+ }
+
+ /* Form RS code generator polynomial from its roots */
+ rs->genpoly = (data_t *)malloc(sizeof(data_t)*(nroots+1));
+ if(rs->genpoly == NULL){
+ free(rs->alpha_to);
+ free(rs->index_of);
+ free(rs);
+ rs = NULL;
+ goto done;
+ }
+ 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)
+ ;
+ rs->iprim = 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[modnn(rs,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[modnn(rs,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]];
+ done:;
+
+ return rs;
+}
+
+RS *init_rs(int symsize, int gfpoly, int fcr, int prim, int nroots, int pad)
+{
+ return init_rs_char(symsize, gfpoly, fcr, prim, nroots, pad);
+}
+
+
+void free_rs_char(RS *rs)
+{
+ free(rs->alpha_to);
+ free(rs->index_of);
+ free(rs->genpoly);
+ free(rs);
+}
+
+/* The guts of the Reed-Solomon encoder, meant to be #included
+ * into a function body with the following typedefs, macros and variables supplied
+ * according to the code parameters:
+
+ * data_t - a typedef for the data symbol
+ * data_t data[] - array of NN-NROOTS-PAD and type data_t to be encoded
+ * data_t parity[] - an array of NROOTS and type data_t to be written with parity symbols
+ * NROOTS - the number of roots in the RS code generator polynomial,
+ * which is the same as the number of parity symbols in a block.
+ Integer variable or literal.
+ *
+ * NN - the total number of symbols in a RS block. Integer variable or literal.
+ * PAD - the number of pad symbols in a block. Integer variable or literal.
+ * ALPHA_TO - The address of an array of NN elements to convert Galois field
+ * elements in index (log) form to polynomial form. Read only.
+ * INDEX_OF - The address of an array of NN elements to convert Galois field
+ * elements in polynomial form to index (log) form. Read only.
+ * MODNN - a function to reduce its argument modulo NN. May be inline or a macro.
+ * GENPOLY - an array of NROOTS+1 elements containing the generator polynomial in index form
+
+ * The memset() and memmove() functions are used. The appropriate header
+ * file declaring these functions (usually <string.h>) must be included by the calling
+ * program.
+
+ * Copyright 2004, Phil Karn, KA9Q
+ * May be used under the terms of the GNU Lesser General Public License (LGPL)
+ */
+
+#undef A0
+#define A0 (NN) /* Special reserved value encoding zero in index form */
+
+void encode_rs_char(RS *rs, const data_t *data, data_t *parity)
+{
+ int i, j;
+ data_t feedback;
+
+ memset(parity,0,NROOTS*sizeof(data_t));
+
+ for(i=0;i<NN-NROOTS-PAD;i++){
+ feedback = INDEX_OF[data[i] ^ parity[0]];
+ if(feedback != A0){ /* feedback term is non-zero */
+#ifdef UNNORMALIZED
+ /* This line is unnecessary when GENPOLY[NROOTS] is unity, as it must
+ * always be for the polynomials constructed by init_rs()
+ */
+ feedback = MODNN(NN - GENPOLY[NROOTS] + feedback);
+#endif
+ for(j=1;j<NROOTS;j++)
+ parity[j] ^= ALPHA_TO[MODNN(feedback + GENPOLY[NROOTS-j])];
+ }
+ /* Shift */
+ memmove(&parity[0],&parity[1],sizeof(data_t)*(NROOTS-1));
+ if(feedback != A0)
+ parity[NROOTS-1] = ALPHA_TO[MODNN(feedback + GENPOLY[0])];
+ else
+ parity[NROOTS-1] = 0;
+ }
+}
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