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Commit 64c70b1c authored by Richard Purdie's avatar Richard Purdie Committed by Linus Torvalds
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Add LZO1X algorithm to the kernel 



This is a hybrid version of the patch to add the LZO1X compression
algorithm to the kernel.  Nitin and myself have merged the best parts of
the various patches to form this version which we're both happy with (and
are jointly signing off).

The performance of this version is equivalent to the original minilzo code
it was based on.  Bytecode comparisons have also been made on ARM, i386 and
x86_64 with favourable results.

There are several users of LZO lined up including jffs2, crypto and reiser4
since its much faster than zlib.

Signed-off-by: default avatarNitin Gupta <nitingupta910@gmail.com>
Signed-off-by: default avatarRichard Purdie <rpurdie@openedhand.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4c75f741

include/linux/lzo.h

0 → 100644
+44 −0
Original line number Diff line number Diff line 
#ifndef __LZO_H__

#define __LZO_H__

/*

 *  LZO Public Kernel Interface

 *  A mini subset of the LZO real-time data compression library

 *

 *  Copyright (C) 1996-2005 Markus F.X.J. Oberhumer <markus@oberhumer.com>

 *

 *  The full LZO package can be found at:

 *  http://www.oberhumer.com/opensource/lzo/

 *

 *  Changed for kernel use by:

 *  Nitin Gupta <nitingupta910@gmail.com>

 *  Richard Purdie <rpurdie@openedhand.com>

 */



#define LZO1X_MEM_COMPRESS	(16384 * sizeof(unsigned char *))

#define LZO1X_1_MEM_COMPRESS	LZO1X_MEM_COMPRESS



#define lzo1x_worst_compress(x) (x + (x / 64) + 16 + 3)



/* This requires 'workmem' of size LZO1X_1_MEM_COMPRESS */

int lzo1x_1_compress(const unsigned char *src, size_t src_len,

			unsigned char *dst, size_t *dst_len, void *wrkmem);



/* safe decompression with overrun testing */

int lzo1x_decompress_safe(const unsigned char *src, size_t src_len,

			unsigned char *dst, size_t *dst_len);



/*

 * Return values (< 0 = Error)

 */

#define LZO_E_OK			0

#define LZO_E_ERROR			(-1)

#define LZO_E_OUT_OF_MEMORY		(-2)

#define LZO_E_NOT_COMPRESSIBLE		(-3)

#define LZO_E_INPUT_OVERRUN		(-4)

#define LZO_E_OUTPUT_OVERRUN		(-5)

#define LZO_E_LOOKBEHIND_OVERRUN	(-6)

#define LZO_E_EOF_NOT_FOUND		(-7)

#define LZO_E_INPUT_NOT_CONSUMED	(-8)

#define LZO_E_NOT_YET_IMPLEMENTED	(-9)



#endif

lib/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -64,6 +64,12 @@ config ZLIB_INFLATE 
config ZLIB_DEFLATE

	tristate



config LZO_COMPRESS

	tristate



config LZO_DECOMPRESS

	tristate



#

# Generic allocator support is selected if needed

#

lib/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -49,6 +49,8 @@ obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o 
obj-$(CONFIG_ZLIB_INFLATE) += zlib_inflate/

obj-$(CONFIG_ZLIB_DEFLATE) += zlib_deflate/

obj-$(CONFIG_REED_SOLOMON) += reed_solomon/

obj-$(CONFIG_LZO_COMPRESS) += lzo/

obj-$(CONFIG_LZO_DECOMPRESS) += lzo/



obj-$(CONFIG_TEXTSEARCH) += textsearch.o

obj-$(CONFIG_TEXTSEARCH_KMP) += ts_kmp.o

lib/lzo/Makefile

0 → 100644
+5 −0
Original line number Diff line number Diff line 
lzo_compress-objs := lzo1x_compress.o

lzo_decompress-objs := lzo1x_decompress.o



obj-$(CONFIG_LZO_COMPRESS) += lzo_compress.o

obj-$(CONFIG_LZO_DECOMPRESS) += lzo_decompress.o

lib/lzo/lzo1x_compress.c

0 → 100644
+226 −0
Original line number Diff line number Diff line 
/*

 *  LZO1X Compressor from MiniLZO

 *

 *  Copyright (C) 1996-2005 Markus F.X.J. Oberhumer <markus@oberhumer.com>

 *

 *  The full LZO package can be found at:

 *  http://www.oberhumer.com/opensource/lzo/

 *

 *  Changed for kernel use by:

 *  Nitin Gupta <nitingupta910@gmail.com>

 *  Richard Purdie <rpurdie@openedhand.com>

 */



#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/lzo.h>

#include <asm/unaligned.h>

#include "lzodefs.h"



static noinline size_t

_lzo1x_1_do_compress(const unsigned char *in, size_t in_len,

		unsigned char *out, size_t *out_len, void *wrkmem)

{

	const unsigned char * const in_end = in + in_len;

	const unsigned char * const ip_end = in + in_len - M2_MAX_LEN - 5;

	const unsigned char ** const dict = wrkmem;

	const unsigned char *ip = in, *ii = ip;

	const unsigned char *end, *m, *m_pos;

	size_t m_off, m_len, dindex;

	unsigned char *op = out;



	ip += 4;



	for (;;) {

		dindex = ((0x21 * DX3(ip, 5, 5, 6)) >> 5) & D_MASK;

		m_pos = dict[dindex];



		if (m_pos < in)

			goto literal;



		if (ip == m_pos || (ip - m_pos) > M4_MAX_OFFSET)

			goto literal;



		m_off = ip - m_pos;

		if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])

			goto try_match;



		dindex = (dindex & (D_MASK & 0x7ff)) ^ (D_HIGH | 0x1f);

		m_pos = dict[dindex];



		if (m_pos < in)

			goto literal;



		if (ip == m_pos || (ip - m_pos) > M4_MAX_OFFSET)

			goto literal;



		m_off = ip - m_pos;

		if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])

			goto try_match;



		goto literal;



try_match:

		if (get_unaligned((const unsigned short *)m_pos)

				== get_unaligned((const unsigned short *)ip)) {

			if (likely(m_pos[2] == ip[2]))

					goto match;

		}



literal:

		dict[dindex] = ip;

		++ip;

		if (unlikely(ip >= ip_end))

			break;

		continue;



match:

		dict[dindex] = ip;

		if (ip != ii) {

			size_t t = ip - ii;



			if (t <= 3) {

				op[-2] |= t;

			} else if (t <= 18) {

				*op++ = (t - 3);

			} else {

				size_t tt = t - 18;



				*op++ = 0;

				while (tt > 255) {

					tt -= 255;

					*op++ = 0;

				}

				*op++ = tt;

			}

			do {

				*op++ = *ii++;

			} while (--t > 0);

		}



		ip += 3;

		if (m_pos[3] != *ip++ || m_pos[4] != *ip++

				|| m_pos[5] != *ip++ || m_pos[6] != *ip++

				|| m_pos[7] != *ip++ || m_pos[8] != *ip++) {

			--ip;

			m_len = ip - ii;



			if (m_off <= M2_MAX_OFFSET) {

				m_off -= 1;

				*op++ = (((m_len - 1) << 5)

						| ((m_off & 7) << 2));

				*op++ = (m_off >> 3);

			} else if (m_off <= M3_MAX_OFFSET) {

				m_off -= 1;

				*op++ = (M3_MARKER | (m_len - 2));

				goto m3_m4_offset;

			} else {

				m_off -= 0x4000;



				*op++ = (M4_MARKER | ((m_off & 0x4000) >> 11)

						| (m_len - 2));

				goto m3_m4_offset;

			}

		} else {

			end = in_end;

			m = m_pos + M2_MAX_LEN + 1;



			while (ip < end && *m == *ip) {

				m++;

				ip++;

			}

			m_len = ip - ii;



			if (m_off <= M3_MAX_OFFSET) {

				m_off -= 1;

				if (m_len <= 33) {

					*op++ = (M3_MARKER | (m_len - 2));

				} else {

					m_len -= 33;

					*op++ = M3_MARKER | 0;

					goto m3_m4_len;

				}

			} else {

				m_off -= 0x4000;

				if (m_len <= M4_MAX_LEN) {

					*op++ = (M4_MARKER

						| ((m_off & 0x4000) >> 11)

						| (m_len - 2));

				} else {

					m_len -= M4_MAX_LEN;

					*op++ = (M4_MARKER

						| ((m_off & 0x4000) >> 11));

m3_m4_len:

					while (m_len > 255) {

						m_len -= 255;

						*op++ = 0;

					}



					*op++ = (m_len);

				}

			}

m3_m4_offset:

			*op++ = ((m_off & 63) << 2);

			*op++ = (m_off >> 6);

		}



		ii = ip;

		if (unlikely(ip >= ip_end))

			break;

	}



	*out_len = op - out;

	return in_end - ii;

}



int lzo1x_1_compress(const unsigned char *in, size_t in_len, unsigned char *out,

			size_t *out_len, void *wrkmem)

{

	const unsigned char *ii;

	unsigned char *op = out;

	size_t t;



	if (unlikely(in_len <= M2_MAX_LEN + 5)) {

		t = in_len;

	} else {

		t = _lzo1x_1_do_compress(in, in_len, op, out_len, wrkmem);

		op += *out_len;

	}



	if (t > 0) {

		ii = in + in_len - t;



		if (op == out && t <= 238) {

			*op++ = (17 + t);

		} else if (t <= 3) {

			op[-2] |= t;

		} else if (t <= 18) {

			*op++ = (t - 3);

		} else {

			size_t tt = t - 18;



			*op++ = 0;

			while (tt > 255) {

				tt -= 255;

				*op++ = 0;

			}



			*op++ = tt;

		}

		do {

			*op++ = *ii++;

		} while (--t > 0);

	}



	*op++ = M4_MARKER | 1;

	*op++ = 0;

	*op++ = 0;



	*out_len = op - out;

	return LZO_E_OK;

}

EXPORT_SYMBOL_GPL(lzo1x_1_compress);



MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("LZO1X-1 Compressor");