156 lines
4.0 KiB
C
156 lines
4.0 KiB
C
/*
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* msi.c -- encoding for MSI-Plessey
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*
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* Copyright (c) 2000 Leonid A. Broukhis (leob@mailcom.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <ctype.h>
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#include <errno.h>
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#include "barcode.h"
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/* Patterns */
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static char *patterns[] = { "13", "31" };
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static char *fillers[] = { "031", "131" };
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static int width = 16 /* each character uses 4 patterns */,
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startpos = 6 /* length of the first filler */;
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/*
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* Check that the text can be encoded. Returns 0 or -1.
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*/
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int Barcode_msi_verify(unsigned char *text)
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{
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int i;
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if (!strlen(text))
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return -1;
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for (i=0; text[i]; i++) {
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if (!isdigit(text[i]))
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return -1;
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}
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return 0;
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}
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static int add_one(char *ptr, int code)
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{
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sprintf(ptr, "%s%s%s%s",
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patterns[(code >> 3) & 1],
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patterns[(code >> 2) & 1],
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patterns[(code >> 1) & 1],
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patterns[code & 1]);
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return 0;
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}
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/*
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* The encoding functions fills the "partial" and "textinfo" fields.
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* Lowercase chars are converted to uppercase
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*/
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int Barcode_msi_encode(struct Barcode_Item *bc)
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{
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static char *text;
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static char *partial; /* dynamic */
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static char *textinfo; /* dynamic */
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char *ptr, *textptr;
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int i, code, textpos, usesum, checksum = 0;
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if (bc->partial)
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free(bc->partial);
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if (bc->textinfo)
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free(bc->textinfo);
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bc->partial = bc->textinfo = NULL; /* safe */
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if (!bc->encoding)
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bc->encoding = strdup("msi");
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if ((bc->flags & BARCODE_NO_CHECKSUM))
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usesum = 0;
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else
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usesum = 1;
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text = bc->ascii;
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/* the partial code is head + 8 * (text + check) + tail + margin + term. */
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partial = malloc( 3 + 8 * (strlen(text) + 1) + 3 + 2 );
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if (!partial) {
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bc->error = errno;
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return -1;
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}
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/* the text information is at most "nnn:fff:c " * strlen +term */
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textinfo = malloc(10*strlen(text) + 2);
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if (!textinfo) {
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bc->error = errno;
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free(partial);
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return -1;
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}
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strcpy(partial, fillers[0]);
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ptr = partial + strlen(partial);
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textptr = textinfo;
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textpos = startpos;
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for (i=0; i<strlen(text); i++) {
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code = text[i] - '0';
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add_one(ptr, code);
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sprintf(textptr, "%i:12:%c ", textpos, text[i]);
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textpos += width; /* width of each code */
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textptr += strlen(textptr);
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ptr += strlen(ptr);
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if (usesum) {
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/* For a code ...FEDCBA the checksum is computed
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* as the sum of digits of the number ...FDB plus
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* the sum of digits of the number ...ECA * 2.
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* Which is equivalent to the sum of each digit of ...ECA doubled
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* plus carry.
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*/
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if ((i ^ strlen(text)) & 1) {
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/* a last digit, 2 away from last, etc. */
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checksum += 2 * code + (2 * code) / 10;
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} else {
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checksum += code;
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}
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}
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}
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/* Some implementations use a double checksum. Currently the only way
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* to print a barcode with double checksum is to put the checksum
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* digit printed below at the end of a code in the command line
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* and re-run the program.
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*/
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if (usesum) {
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/* the check digit is the complement of the checksum
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* to a multiple of 10.
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*/
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checksum = (checksum + 9) / 10 * 10 - checksum;
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/* fprintf(stderr, "Checksum: %d\n", checksum); */
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add_one(ptr, checksum);
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ptr += strlen(ptr);
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}
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strcpy(ptr, fillers[1]);
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bc->partial = partial;
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bc->textinfo = textinfo;
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return 0;
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}
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