From 3e64690f20260eb01ea440d745c177930fba6568 Mon Sep 17 00:00:00 2001
From: bernie <bernie@38d2e660-2303-0410-9eaa-f027e97ec537>
Date: Wed, 4 Aug 2004 02:35:54 +0000
Subject: [PATCH] Import simple RLE algorithm.

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@103 38d2e660-2303-0410-9eaa-f027e97ec537
---
 mware/rle.c | 133 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 mware/rle.h |  27 +++++++++++
 2 files changed, 160 insertions(+)
 create mode 100755 mware/rle.c
 create mode 100755 mware/rle.h

diff --git a/mware/rle.c b/mware/rle.c
new file mode 100755
index 00000000..4655ab66
--- /dev/null
+++ b/mware/rle.c
@@ -0,0 +1,133 @@
+/*!
+ * \file
+ * <!--
+ * Copyright 2004 Develer S.r.l. (http://www.develer.com/)
+ * Copyright 1999, 2000, 2001 Bernardo Innocenti <bernie@develer.com>
+ * This file is part of DevLib - See devlib/README for information.
+ * -->
+ *
+ * \brief General-purpose run-length {en,de}coding algorithm (implementation)
+ *
+ * Original source code from http://www.compuphase.com/compress.htm
+ *
+ * \version $Id$
+ * \author Bernardo Innocenti <bernie@develer.com>
+ */
+
+/*
+ * $Log$
+ * Revision 1.1  2004/08/04 02:35:54  bernie
+ * Import simple RLE algorithm.
+ *
+ */
+
+#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);
+}
diff --git a/mware/rle.h b/mware/rle.h
new file mode 100755
index 00000000..b23da7dd
--- /dev/null
+++ b/mware/rle.h
@@ -0,0 +1,27 @@
+/*!
+ * \file
+ * <!--
+ * Copyright 2004 Develer S.r.l. (http://www.develer.com/)
+ * Copyright 1999, 2000, 2001 Bernardo Innocenti <bernie@develer.com>
+ * This file is part of DevLib - See devlib/README for information.
+ * -->
+ *
+ * \brief General-purpose run-length {en,de}coding algorithm (interface)
+ *
+ * \version $Id$
+ * \author Bernardo Innocenti <bernie@develer.com>
+ */
+
+/*
+ * $Log$
+ * Revision 1.1  2004/08/04 02:35:54  bernie
+ * Import simple RLE algorithm.
+ *
+ */
+#ifndef RLE_H
+#define RLE_H
+
+int rle(unsigned char *output, const unsigned char *input, int length);
+int unrle(unsigned char *output, const unsigned char *input);
+
+#endif /* RLE_H */
-- 
2.25.1