1 /*------------------------------------------------------------------------
2 * Copyright 2007-2009 (c) Jeff Brown <spadix@users.sourceforge.net>
3 *
4 * This file is part of the ZBar Bar Code Reader.
5 *
6 * The ZBar Bar Code Reader is free software; you can redistribute it
7 * and/or modify it under the terms of the GNU Lesser Public License as
8 * published by the Free Software Foundation; either version 2.1 of
9 * the License, or (at your option) any later version.
10 *
11 * The ZBar Bar Code Reader is distributed in the hope that it will be
12 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
13 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU Lesser Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser Public License
17 * along with the ZBar Bar Code Reader; if not, write to the Free
18 * Software Foundation, Inc., 51 Franklin St, Fifth Floor,
19 * Boston, MA 02110-1301 USA
20 *
21 * http://sourceforge.net/projects/zbar
22 *------------------------------------------------------------------------*/
23 #ifndef _DECODER_H_
24 #define _DECODER_H_
25
26 #include <stdlib.h> /* realloc */
27
28 #include <zbar.h>
29
30 #define NUM_CFGS (ZBAR_CFG_MAX_LEN - ZBAR_CFG_MIN_LEN + 1)
31
32 #ifdef ENABLE_EAN
33 # include "decoder/ean.h"
34 #endif
35 #ifdef ENABLE_I25
36 # include "decoder/i25.h"
37 #endif
38 #ifdef ENABLE_CODE39
39 # include "decoder/code39.h"
40 #endif
41 #ifdef ENABLE_CODE128
42 # include "decoder/code128.h"
43 #endif
44 #ifdef ENABLE_PDF417
45 # include "decoder/pdf417.h"
46 #endif
47 #ifdef ENABLE_QRCODE
48 # include "decoder/qr_finder.h"
49 #endif
50
51 /* size of bar width history (implementation assumes power of two) */
52 #ifndef DECODE_WINDOW
53 # define DECODE_WINDOW 16
54 #endif
55
56 /* initial data buffer allocation */
57 #ifndef BUFFER_MIN
58 # define BUFFER_MIN 0x20
59 #endif
60
61 /* maximum data buffer allocation
62 * (longer symbols are rejected)
63 */
64 #ifndef BUFFER_MAX
65 # define BUFFER_MAX 0x100
66 #endif
67
68 /* buffer allocation increment */
69 #ifndef BUFFER_INCR
70 # define BUFFER_INCR 0x10
71 #endif
72
73 #define CFG(dcode, cfg) ((dcode).configs[(cfg) - ZBAR_CFG_MIN_LEN])
74 #define TEST_CFG(config, cfg) (((config) >> (cfg)) & 1)
75
76 /* symbology independent decoder state */
77 struct zbar_decoder_s {
78 unsigned char idx; /* current width index */
79 unsigned w[DECODE_WINDOW]; /* window of last N bar widths */
80 zbar_symbol_type_t type; /* type of last decoded data */
81 zbar_symbol_type_t lock; /* buffer lock */
82
83 /* everything above here is automatically reset */
84 unsigned buf_alloc; /* dynamic buffer allocation */
85 unsigned buflen; /* binary data length */
86 unsigned char *buf; /* decoded characters */
87 void *userdata; /* application data */
88 zbar_decoder_handler_t *handler; /* application callback */
89
90 /* symbology specific state */
91 #ifdef ENABLE_EAN
92 ean_decoder_t ean; /* EAN/UPC parallel decode attempts */
93 #endif
94 #ifdef ENABLE_I25
95 i25_decoder_t i25; /* Interleaved 2 of 5 decode state */
96 #endif
97 #ifdef ENABLE_CODE39
98 code39_decoder_t code39; /* Code 39 decode state */
99 #endif
100 #ifdef ENABLE_CODE128
101 code128_decoder_t code128; /* Code 128 decode state */
102 #endif
103 #ifdef ENABLE_PDF417
104 pdf417_decoder_t pdf417; /* PDF417 decode state */
105 #endif
106 #ifdef ENABLE_QRCODE
107 qr_finder_t qrf; /* QR Code finder state */
108 #endif
109 };
110
111 /* return current element color */
get_color(const zbar_decoder_t * dcode)112 static inline char get_color (const zbar_decoder_t *dcode)
113 {
114 return(dcode->idx & 1);
115 }
116
117 /* retrieve i-th previous element width */
get_width(const zbar_decoder_t * dcode,unsigned char offset)118 static inline unsigned get_width (const zbar_decoder_t *dcode,
119 unsigned char offset)
120 {
121 return(dcode->w[(dcode->idx - offset) & (DECODE_WINDOW - 1)]);
122 }
123
124 /* retrieve bar+space pair width starting at offset i */
pair_width(const zbar_decoder_t * dcode,unsigned char offset)125 static inline unsigned pair_width (const zbar_decoder_t *dcode,
126 unsigned char offset)
127 {
128 return(get_width(dcode, offset) + get_width(dcode, offset + 1));
129 }
130
131 /* calculate total character width "s"
132 * - start of character identified by context sensitive offset
133 * (<= DECODE_WINDOW - n)
134 * - size of character is n elements
135 */
calc_s(const zbar_decoder_t * dcode,unsigned char offset,unsigned char n)136 static inline unsigned calc_s (const zbar_decoder_t *dcode,
137 unsigned char offset,
138 unsigned char n)
139 {
140 /* FIXME check that this gets unrolled for constant n */
141 unsigned s = 0;
142 while(n--)
143 s += get_width(dcode, offset++);
144 return(s);
145 }
146
147 /* fixed character width decode assist
148 * bar+space width are compared as a fraction of the reference dimension "x"
149 * - +/- 1/2 x tolerance
150 * - measured total character width (s) compared to symbology baseline (n)
151 * (n = 7 for EAN/UPC, 11 for Code 128)
152 * - bar+space *pair width* "e" is used to factor out bad "exposures"
153 * ("blooming" or "swelling" of dark or light areas)
154 * => using like-edge measurements avoids these issues
155 * - n should be > 3
156 */
decode_e(unsigned e,unsigned s,unsigned n)157 static inline int decode_e (unsigned e,
158 unsigned s,
159 unsigned n)
160 {
161 /* result is encoded number of units - 2
162 * (for use as zero based index)
163 * or -1 if invalid
164 */
165 unsigned char E = ((e * n * 2 + 1) / s - 3) / 2;
166 return((E >= n - 3) ? -1 : E);
167 }
168
169 /* acquire shared state lock */
get_lock(zbar_decoder_t * dcode,zbar_symbol_type_t req)170 static inline char get_lock (zbar_decoder_t *dcode,
171 zbar_symbol_type_t req)
172 {
173 if(dcode->lock)
174 return(1);
175 dcode->lock = req;
176 return(0);
177 }
178
179 /* ensure output buffer has sufficient allocation for request */
size_buf(zbar_decoder_t * dcode,unsigned len)180 static inline char size_buf (zbar_decoder_t *dcode,
181 unsigned len)
182 {
183 if(len < dcode->buf_alloc)
184 /* FIXME size reduction heuristic? */
185 return(0);
186 if(len > BUFFER_MAX)
187 return(1);
188 if(len < dcode->buf_alloc + BUFFER_INCR) {
189 len = dcode->buf_alloc + BUFFER_INCR;
190 if(len > BUFFER_MAX)
191 len = BUFFER_MAX;
192 }
193 unsigned char *buf = realloc(dcode->buf, len);
194 if(!buf)
195 return(1);
196 dcode->buf = buf;
197 dcode->buf_alloc = len;
198 return(0);
199 }
200
201 extern const char *_zbar_decoder_buf_dump (unsigned char *buf,
202 unsigned int buflen);
203
204 #endif
205