Diff: decoder.h

Revision:

0:e33621169e44

diff -r 000000000000 -r e33621169e44 decoder.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/decoder.h	Fri Jan 10 20:29:52 2020 +0000
@@ -0,0 +1,205 @@
+/*------------------------------------------------------------------------
+ *  Copyright 2007-2009 (c) Jeff Brown <spadix@users.sourceforge.net>
+ *
+ *  This file is part of the ZBar Bar Code Reader.
+ *
+ *  The ZBar Bar Code Reader is free software; you can redistribute it
+ *  and/or modify it under the terms of the GNU Lesser Public License as
+ *  published by the Free Software Foundation; either version 2.1 of
+ *  the License, or (at your option) any later version.
+ *
+ *  The ZBar Bar Code Reader 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 Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser Public License
+ *  along with the ZBar Bar Code Reader; if not, write to the Free
+ *  Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ *  Boston, MA  02110-1301  USA
+ *
+ *  http://sourceforge.net/projects/zbar
+ *------------------------------------------------------------------------*/
+#ifndef _DECODER_H_
+#define _DECODER_H_
+
+#include "config.h"
+#include <stdlib.h>     /* realloc */
+
+#include <zbar.h>
+
+#define NUM_CFGS (ZBAR_CFG_MAX_LEN - ZBAR_CFG_MIN_LEN + 1)
+
+#ifdef ENABLE_EAN
+# include "decoder/ean.h"
+#endif
+#ifdef ENABLE_I25
+# include "decoder/i25.h"
+#endif
+#ifdef ENABLE_CODE39
+# include "decoder/code39.h"
+#endif
+#ifdef ENABLE_CODE128
+# include "decoder/code128.h"
+#endif
+#ifdef ENABLE_PDF417
+# include "decoder/pdf417.h"
+#endif
+#ifdef ENABLE_QRCODE
+# include "decoder/qr_finder.h"
+#endif
+
+/* size of bar width history (implementation assumes power of two) */
+#ifndef DECODE_WINDOW
+# define DECODE_WINDOW  16
+#endif
+
+/* initial data buffer allocation */
+#ifndef BUFFER_MIN
+# define BUFFER_MIN   0x20
+#endif
+
+/* maximum data buffer allocation
+ * (longer symbols are rejected)
+ */
+#ifndef BUFFER_MAX
+# define BUFFER_MAX  0x100
+#endif
+
+/* buffer allocation increment */
+#ifndef BUFFER_INCR
+# define BUFFER_INCR  0x10
+#endif
+
+#define CFG(dcode, cfg) ((dcode).configs[(cfg) - ZBAR_CFG_MIN_LEN])
+#define TEST_CFG(config, cfg) (((config) >> (cfg)) & 1)
+
+/* symbology independent decoder state */
+struct zbar_decoder_s {
+    unsigned char idx;                  /* current width index */
+    unsigned w[DECODE_WINDOW];          /* window of last N bar widths */
+    zbar_symbol_type_t type;            /* type of last decoded data */
+    zbar_symbol_type_t lock;            /* buffer lock */
+
+    /* everything above here is automatically reset */
+    unsigned buf_alloc;                 /* dynamic buffer allocation */
+    unsigned buflen;                    /* binary data length */
+    unsigned char *buf;                 /* decoded characters */
+    void *userdata;                     /* application data */
+    zbar_decoder_handler_t *handler;    /* application callback */
+
+    /* symbology specific state */
+#ifdef ENABLE_EAN
+    ean_decoder_t ean;                  /* EAN/UPC parallel decode attempts */
+#endif
+#ifdef ENABLE_I25
+    i25_decoder_t i25;                  /* Interleaved 2 of 5 decode state */
+#endif
+#ifdef ENABLE_CODE39
+    code39_decoder_t code39;            /* Code 39 decode state */
+#endif
+#ifdef ENABLE_CODE128
+    code128_decoder_t code128;          /* Code 128 decode state */
+#endif
+#ifdef ENABLE_PDF417
+    pdf417_decoder_t pdf417;            /* PDF417 decode state */
+#endif
+#ifdef ENABLE_QRCODE
+    qr_finder_t qrf;                    /* QR Code finder state */
+#endif
+};
+
+/* return current element color */
+static inline char get_color (const zbar_decoder_t *dcode)
+{
+    return(dcode->idx & 1);
+}
+
+/* retrieve i-th previous element width */
+static inline unsigned get_width (const zbar_decoder_t *dcode,
+                                  unsigned char offset)
+{
+    return(dcode->w[(dcode->idx - offset) & (DECODE_WINDOW - 1)]);
+}
+
+/* retrieve bar+space pair width starting at offset i */
+static inline unsigned pair_width (const zbar_decoder_t *dcode,
+                                   unsigned char offset)
+{
+    return(get_width(dcode, offset) + get_width(dcode, offset + 1));
+}
+
+/* calculate total character width "s"
+ *   - start of character identified by context sensitive offset
+ *     (<= DECODE_WINDOW - n)
+ *   - size of character is n elements
+ */
+static inline unsigned calc_s (const zbar_decoder_t *dcode,
+                               unsigned char offset,
+                               unsigned char n)
+{
+    /* FIXME check that this gets unrolled for constant n */
+    unsigned s = 0;
+    while(n--)
+        s += get_width(dcode, offset++);
+    return(s);
+}
+
+/* fixed character width decode assist
+ * bar+space width are compared as a fraction of the reference dimension "x"
+ *   - +/- 1/2 x tolerance
+ *   - measured total character width (s) compared to symbology baseline (n)
+ *     (n = 7 for EAN/UPC, 11 for Code 128)
+ *   - bar+space *pair width* "e" is used to factor out bad "exposures"
+ *     ("blooming" or "swelling" of dark or light areas)
+ *     => using like-edge measurements avoids these issues
+ *   - n should be > 3
+ */
+static inline int decode_e (unsigned e,
+                            unsigned s,
+                            unsigned n)
+{
+    /* result is encoded number of units - 2
+     * (for use as zero based index)
+     * or -1 if invalid
+     */
+    unsigned char E = ((e * n * 2 + 1) / s - 3) / 2;
+    return((E >= n - 3) ? -1 : E);
+}
+
+/* acquire shared state lock */
+static inline char get_lock (zbar_decoder_t *dcode,
+                             zbar_symbol_type_t req)
+{
+    if(dcode->lock)
+        return(1);
+    dcode->lock = req;
+    return(0);
+}
+
+/* ensure output buffer has sufficient allocation for request */
+static inline char size_buf (zbar_decoder_t *dcode,
+                             unsigned len)
+{
+    if(len < dcode->buf_alloc)
+        /* FIXME size reduction heuristic? */
+        return(0);
+    if(len > BUFFER_MAX)
+        return(1);
+    if(len < dcode->buf_alloc + BUFFER_INCR) {
+        len = dcode->buf_alloc + BUFFER_INCR;
+        if(len > BUFFER_MAX)
+            len = BUFFER_MAX;
+    }
+    unsigned char *buf = realloc(dcode->buf, len);
+    if(!buf)
+        return(1);
+    dcode->buf = buf;
+    dcode->buf_alloc = len;
+    return(0);
+}
+
+extern const char *_zbar_decoder_buf_dump (unsigned char *buf,
+                                            unsigned int buflen);
+
+#endif