openwrt/target/linux/ar71xx/patches-4.14/310-lib-add-rle-decompression.patch

--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -265,6 +265,9 @@ config LZMA_COMPRESS
 config LZMA_DECOMPRESS
     tristate
 
+config RLE_DECOMPRESS
+	tristate
+
 #
 # These all provide a common interface (hence the apparent duplication with
 # ZLIB_INFLATE; DECOMPRESS_GZIP is just a wrapper.)
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -146,6 +146,7 @@ obj-$(CONFIG_XZ_DEC) += xz/
 obj-$(CONFIG_RAID6_PQ) += raid6/
 obj-$(CONFIG_LZMA_COMPRESS) += lzma/
 obj-$(CONFIG_LZMA_DECOMPRESS) += lzma/
+obj-$(CONFIG_RLE_DECOMPRESS) += rle.o
 
 lib-$(CONFIG_DECOMPRESS_GZIP) += decompress_inflate.o
 lib-$(CONFIG_DECOMPRESS_BZIP2) += decompress_bunzip2.o
--- /dev/null
+++ b/include/linux/rle.h
@@ -0,0 +1,18 @@
+#ifndef _RLE_H_
+#define _RLE_H_
+
+#ifdef CONFIG_RLE_DECOMPRESS
+int rle_decode(const unsigned char *src, size_t srclen,
+	       unsigned char *dst, size_t dstlen,
+	       size_t *src_done, size_t *dst_done);
+#else
+static inline int
+rle_decode(const unsigned char *src, size_t srclen,
+	   unsigned char *dst, size_t dstlen,
+	   size_t *src_done, size_t *dst_done)
+{
+	return -ENOTSUPP;
+}
+#endif /* CONFIG_RLE_DECOMPRESS */
+
+#endif /* _RLE_H_ */
--- /dev/null
+++ b/lib/rle.c
@@ -0,0 +1,78 @@
+/*
+ *  RLE decoding routine
+ *
+ *  Copyright (C) 2012 Gabor Juhos <juhosg@openwrt.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License version 2 as published
+ *  by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/rle.h>
+
+int rle_decode(const unsigned char *src, size_t srclen,
+	       unsigned char *dst, size_t dstlen,
+	       size_t *src_done, size_t *dst_done)
+{
+	size_t srcpos, dstpos;
+	int ret;
+
+	srcpos = 0;
+	dstpos = 0;
+	ret = -EINVAL;
+
+	/* sanity checks */
+	if (!src || !srclen || !dst || !dstlen)
+		goto out;
+
+	while (1) {
+		char count;
+
+		if (srcpos >= srclen)
+			break;
+
+		count = (char) src[srcpos++];
+		if (count == 0) {
+			ret = 0;
+			break;
+		}
+
+		if (count > 0) {
+			unsigned char c;
+
+			if (srcpos >= srclen)
+				break;
+
+			c = src[srcpos++];
+
+			while (count--) {
+				if (dstpos >= dstlen)
+					break;
+
+				dst[dstpos++] = c;
+			}
+		} else {
+			count *= -1;
+
+			while (count--) {
+				if (srcpos >= srclen)
+					break;
+				if (dstpos >= dstlen)
+					break;
+				dst[dstpos++] = src[srcpos++];
+			}
+		}
+	}
+
+out:
+	if (src_done)
+		*src_done = srcpos;
+	if (dst_done)
+		*dst_done = dstpos;
+
+	return ret;
+}
+
+EXPORT_SYMBOL_GPL(rle_decode);