i25.c

00001 /*------------------------------------------------------------------------
00002  *  Copyright 2008-2009 (c) Jeff Brown <spadix@users.sourceforge.net>
00003  *
00004  *  This file is part of the ZBar Bar Code Reader.
00005  *
00006  *  The ZBar Bar Code Reader is free software; you can redistribute it
00007  *  and/or modify it under the terms of the GNU Lesser Public License as
00008  *  published by the Free Software Foundation; either version 2.1 of
00009  *  the License, or (at your option) any later version.
00010  *
00011  *  The ZBar Bar Code Reader is distributed in the hope that it will be
00012  *  useful, but WITHOUT ANY WARRANTY; without even the implied warranty
00013  *  of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014  *  GNU Lesser Public License for more details.
00015  *
00016  *  You should have received a copy of the GNU Lesser Public License
00017  *  along with the ZBar Bar Code Reader; if not, write to the Free
00018  *  Software Foundation, Inc., 51 Franklin St, Fifth Floor,
00019  *  Boston, MA  02110-1301  USA
00020  *
00021  *  http://sourceforge.net/projects/zbar
00022  *------------------------------------------------------------------------*/
00023 
00024 #include "../config.h"
00025 #include <string.h>     /* memmove */
00026 
00027 #ifdef ENABLE_I25
00028 
00029 #include <zbar.h>
00030 #include "../decoder.h"
00031 
00032 #ifdef DEBUG_I25
00033 # define DEBUG_LEVEL (DEBUG_I25)
00034 #endif
00035 #include "../debug.h"
00036 
00037 static inline unsigned char i25_decode1 (unsigned char enc,
00038                                          unsigned e,
00039                                          unsigned s)
00040 {
00041     unsigned char E = decode_e(e, s, 45);
00042     if(E > 7)
00043         return(0xff);
00044     enc <<= 1;
00045     if(E > 2)
00046         enc |= 1;
00047     return(enc);
00048 }
00049 
00050 static inline unsigned char i25_decode10 (zbar_decoder_t *dcode,
00051                                           unsigned char offset)
00052 {
00053     i25_decoder_t *dcode25 = &dcode->i25;
00054     dprintf(2, " s=%d", dcode25->s10);
00055     if(dcode25->s10 < 10)
00056         return(0xff);
00057 
00058     /* threshold bar width ratios */
00059     unsigned char enc = 0, par = 0;
00060     signed char i;
00061     for(i = 8; i >= 0; i -= 2) {
00062         unsigned char j = offset + ((dcode25->direction) ? i : 8 - i);
00063         enc = i25_decode1(enc, get_width(dcode, j), dcode25->s10);
00064         if(enc == 0xff)
00065             return(0xff);
00066         if(enc & 1)
00067             par++;
00068     }
00069 
00070     dprintf(2, " enc=%02x par=%x", enc, par);
00071 
00072     /* parity check */
00073     if(par != 2) {
00074         dprintf(2, " [bad parity]");
00075         return(0xff);
00076     }
00077 
00078     /* decode binary weights */
00079     enc &= 0xf;
00080     if(enc & 8) {
00081         if(enc == 12)
00082             enc = 0;
00083         else if(--enc > 9) {
00084             dprintf(2, " [invalid encoding]");
00085             return(0xff);
00086         }
00087     }
00088 
00089     dprintf(2, " => %x", enc);
00090     return(enc);
00091 }
00092 
00093 static inline signed char i25_decode_start (zbar_decoder_t *dcode)
00094 {
00095     i25_decoder_t *dcode25 = &dcode->i25;
00096     if(dcode25->s10 < 10)
00097         return(ZBAR_NONE);
00098 
00099     unsigned char enc = 0;
00100     unsigned char i = 10;
00101     enc = i25_decode1(enc, get_width(dcode, i++), dcode25->s10);
00102     enc = i25_decode1(enc, get_width(dcode, i++), dcode25->s10);
00103     enc = i25_decode1(enc, get_width(dcode, i++), dcode25->s10);
00104 
00105     if((get_color(dcode) == ZBAR_BAR)
00106        ? enc != 4
00107        : (enc = i25_decode1(enc, get_width(dcode, i++), dcode25->s10))) {
00108         dprintf(4, "      i25: s=%d enc=%x [invalid]\n", dcode25->s10, enc);
00109         return(ZBAR_NONE);
00110     }
00111 
00112     /* check leading quiet zone - spec is 10n(?)
00113      * we require 5.25n for w=2n to 6.75n for w=3n
00114      * (FIXME should really factor in w:n ratio)
00115      */
00116     unsigned quiet = get_width(dcode, i++);
00117     if(quiet && quiet < dcode25->s10 * 3 / 8) {
00118         dprintf(3, "      i25: s=%d enc=%x q=%d [invalid qz]\n",
00119                 dcode25->s10, enc, quiet);
00120         return(ZBAR_NONE);
00121     }
00122 
00123     dcode25->direction = get_color(dcode);
00124     dcode25->element = 1;
00125     dcode25->character = 0;
00126     return(ZBAR_PARTIAL);
00127 }
00128 
00129 static inline signed char i25_decode_end (zbar_decoder_t *dcode)
00130 {
00131     i25_decoder_t *dcode25 = &dcode->i25;
00132 
00133     /* check trailing quiet zone */
00134     unsigned quiet = get_width(dcode, 0);
00135     if((quiet && quiet < dcode25->width * 3 / 8) ||
00136        decode_e(get_width(dcode, 1), dcode25->width, 45) > 2 ||
00137        decode_e(get_width(dcode, 2), dcode25->width, 45) > 2) {
00138         dprintf(3, " s=%d q=%d [invalid qz]\n", dcode25->width, quiet);
00139         return(ZBAR_NONE);
00140     }
00141 
00142     /* check exit condition */
00143     unsigned char E = decode_e(get_width(dcode, 3), dcode25->width, 45);
00144     if((!dcode25->direction)
00145        ? E - 3 > 4
00146        : (E > 2 ||
00147           decode_e(get_width(dcode, 4), dcode25->width, 45) > 2))
00148         return(ZBAR_NONE);
00149 
00150     if(dcode25->direction) {
00151         /* reverse buffer */
00152         dprintf(2, " (rev)");
00153         int i;
00154         for(i = 0; i < dcode25->character / 2; i++) {
00155             unsigned j = dcode25->character - 1 - i;
00156             char c = dcode->buf[i];
00157             dcode->buf[i] = dcode->buf[j];
00158             dcode->buf[j] = c;
00159         }
00160     }
00161 
00162     if(dcode25->character < CFG(*dcode25, ZBAR_CFG_MIN_LEN) ||
00163        (CFG(*dcode25, ZBAR_CFG_MAX_LEN) > 0 &&
00164         dcode25->character > CFG(*dcode25, ZBAR_CFG_MAX_LEN))) {
00165         dprintf(2, " [invalid len]\n");
00166         dcode->lock = 0;
00167         dcode25->character = -1;
00168         return(ZBAR_NONE);
00169     }
00170 
00171     dcode->buflen = dcode25->character;
00172     dcode->buf[dcode25->character] = '\0';
00173     dprintf(2, " [valid end]\n");
00174     dcode25->character = -1;
00175     return(ZBAR_I25);
00176 }
00177 
00178 zbar_symbol_type_t _zbar_decode_i25 (zbar_decoder_t *dcode)
00179 {
00180     i25_decoder_t *dcode25 = &dcode->i25;
00181 
00182     /* update latest character width */
00183     dcode25->s10 -= get_width(dcode, 10);
00184     dcode25->s10 += get_width(dcode, 0);
00185 
00186     if(dcode25->character < 0 &&
00187        !i25_decode_start(dcode))
00188         return(ZBAR_NONE);
00189 
00190     if(--dcode25->element == 6 - dcode25->direction)
00191         return(i25_decode_end(dcode));
00192     else if(dcode25->element)
00193         return(ZBAR_NONE);
00194 
00195     /* FIXME check current character width against previous */
00196     dcode25->width = dcode25->s10;
00197 
00198     dprintf(2, "      i25[%c%02d+%x]",
00199             (dcode25->direction) ? '<' : '>',
00200             dcode25->character, dcode25->element);
00201 
00202     /* lock shared resources */
00203     if(!dcode25->character && get_lock(dcode, ZBAR_I25)) {
00204         dcode25->character = -1;
00205         dprintf(2, " [locked %d]\n", dcode->lock);
00206         return(ZBAR_PARTIAL);
00207     }
00208 
00209     unsigned char c = i25_decode10(dcode, 1);
00210     dprintf(2, " c=%x", c);
00211 
00212     if(c > 9 ||
00213        ((dcode25->character >= BUFFER_MIN) &&
00214         size_buf(dcode, dcode25->character + 2))) {
00215         dprintf(2, (c > 9) ? " [aborted]\n" : " [overflow]\n");
00216         dcode->lock = 0;
00217         dcode25->character = -1;
00218         return(ZBAR_NONE);
00219     }
00220     dcode->buf[dcode25->character++] = c + '0';
00221 
00222     c = i25_decode10(dcode, 0);
00223     dprintf(2, " c=%x", c);
00224     if(c > 9) {
00225         dprintf(2, " [aborted]\n");
00226         dcode->lock = 0;
00227         dcode25->character = -1;
00228         return(ZBAR_NONE);
00229     }
00230     else
00231         dprintf(2, "\n");
00232 
00233     dcode->buf[dcode25->character++] = c + '0';
00234     dcode25->element = 10;
00235     return((dcode25->character == 2) ? ZBAR_PARTIAL : ZBAR_NONE);
00236 }
00237 
00238 #endif