--- a/lib/Kconfig +++ b/lib/Kconfig @@ -221,6 +221,9 @@ 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 @@ -94,6 +94,7 @@ 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);