+/**
+ * \file
+ * <!--
+ * This file is part of BeRTOS.
+ *
+ * Bertos is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction. Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License. This exception does not however
+ * invalidate any other reasons why the executable file might be covered by
+ * the GNU General Public License.
+ *
+ * Copyright 2004 Develer S.r.l. (http://www.develer.com/)
+ * Copyright 1999, 2000, 2001 Bernie Innocenti <bernie@codewiz.org>
+ *
+ * -->
+ *
+ * \brief General-purpose run-length {en,de}coding algorithm (implementation)
+ *
+ * Original source code from http://www.compuphase.com/compress.htm
+ *
+ * \version $Id$
+ * \author Bernie Innocenti <bernie@codewiz.org>
+ */
+
+#include "rle.h"
+
+
+/**
+ * Run-length encode \a len bytes from the \a input buffer
+ * to the \a output buffer.
+ */
+int rle(unsigned char *output, const unsigned char *input, int len)
+{
+ int count, index, i;
+ unsigned char first;
+ unsigned char *out;
+
+
+ out = output;
+ count = 0;
+ while (count < len)
+ {
+ index = count;
+ first = input[index++];
+
+ /* Scan for bytes identical to the first one */
+ while ((index < len) && (index - count < 127) && (input[index] == first))
+ index++;
+
+ if (index - count == 1)
+ {
+ /* Failed to "replicate" the current byte. See how many to copy.
+ */
+ while ((index < len) && (index - count < 127))
+ {
+ /* Avoid a replicate run of only 2-bytes after a literal run.
+ * There is no gain in this, and there is a risc of loss if the
+ * run after the two identical bytes is another literal run.
+ * So search for 3 identical bytes.
+ */
+ if ((input[index] == input[index - 1]) &&
+ ((index > 1) && (input[index] == input[index - 2])))
+ {
+ /* Reset the index so we can back up these three identical
+ * bytes in the next run.
+ */
+ index -= 2;
+ break;
+ }
+
+ index++;
+ }
+
+ /* Output a run of uncompressed bytes: write length and values */
+ *out++ = (unsigned char)(count - index);
+ for (i = count; i < index; i++)
+ *out++ = input[i];
+ }
+ else
+ {
+ /* Output a compressed run: write length and value */
+ *out++ = (unsigned char)(index - count);
+ *out++ = first;
+ }
+
+ count = index;
+ }
+
+ /* Output EOF marker */
+ *out++ = 0;
+
+ return (out - output);
+}
+
+
+/**
+ * Run-length decode from the \a input buffer to the \a output
+ * buffer.
+ *
+ * \note The output buffer must be large enough to accomodate
+ * all decoded output.
+ */
+int unrle(unsigned char *output, const unsigned char *input)
+{
+ signed char count;
+ unsigned char *out;
+ unsigned char value;
+
+
+ out = output;
+
+ for (;;)
+ {
+ count = (signed char)*input++;
+ if (count > 0)
+ {
+ /* replicate run */
+ value = *input++;
+ while (count--)
+ *out++ = value;
+ }
+ else if (count < 0)
+ {
+ /* literal run */
+ while (count++)
+ *out++ = *input++;
+ }
+ else
+ /* EOF */
+ break;
+ }
+
+ return (out - output);
+}