Thread: [lc-devel] [RFC] LZO de/compression support in kernel [0/5]
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From: Nitin G. <nit...@gm...> - 2007-05-14 12:47:46
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Hi, This is kernel port of LZO1X-1 compression algo stripped down to just ~500 lines! The original code is from: http://www.oberhumer.com/opensource/lzo/download/lzo-2.02.tar.gz This is the same flavour of LZO that we are currently using in compressed caching. Before posting this to LKML, it would be great we replace existing LZO code in ccaching patche with this version. If it can take torture of ccaching then it's good enough for mainline w.r.t stability. Please also look into coding style if it's acceptable for mainline - I did not consider much about the diffability with original LZO code as I just wanted a clean looking code :-) I have created a simple kernel module to test this LZO port. I will refine that a bit and post on http://linux-mm.org/CompressedCaching/Code soon. Any comments/reviews are welcome :) (patches are against 2.6.22-rc1) Cheers, Nitin |
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From: Nitin G. <nit...@gm...> - 2007-05-14 12:51:06
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This is the public interface for LZO de/compression. Index: linux-cc/include/linux/lzo1x.h =================================================================== --- /dev/null +++ linux-cc/include/linux/lzo1x.h @@ -0,0 +1,61 @@ +/* lzo1x.h -- public interface of the LZO1X compression algorithm + + This file is part of the LZO real-time data compression library. + + Copyright (C) 2005 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2004 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2003 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2002 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2001 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2000 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1999 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1998 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1997 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1996 Markus Franz Xaver Johannes Oberhumer + All Rights Reserved. + + The LZO library 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. + + The LZO library 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 the LZO library; see the file COPYING. + If not, write to the Free Software Foundation, Inc., + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + + Markus F.X.J. Oberhumer + <ma...@ob...> + http://www.oberhumer.com/opensource/lzo/ + + + This file is modified version of lzo1x.h found in original LZO 2.02 + code. Some additional changes have also been made to make it work + in kernel space. + + Nitin Gupta + <nit...@gm...> + */ + +#ifndef __LZO1X_H +#define __LZO1X_H + +/* Size of temp buffer (workmem) required by lzo1x_compress */ +#define LZO1X_WORKMEM_SIZE ((size_t) (16384L * sizeof(unsigned char *))) + +/* LZO1X_1 compression */ +int +lzo1x_compress(const unsigned char *src, size_t src_len, + unsigned char *dst, size_t *dst_len, + void *workmem); + +/* LZO1X_1 decompression */ +int +lzo1x_decompress(const unsigned char *src, size_t src_len, + unsigned char *dst, size_t *dst_len); + +#endif |
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From: Nitin G. <nit...@gm...> - 2007-05-14 12:55:39
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This contains stuff used internally by LZO code. This is not intended to be used directly by other modules. Signed-off-by: Nitin Gupta <nit...@gm...> Index: linux-cc/lib/lzo1x/lzo1x_int.h =================================================================== --- /dev/null +++ linux-cc/lib/lzo1x/lzo1x_int.h @@ -0,0 +1,105 @@ +/* lzo1x_int.h -- to be used internally by LZO de/compression algorithms + + This file is part of the LZO real-time data compression library. + + Copyright (C) 2005 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2004 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2003 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2002 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2001 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2000 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1999 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1998 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1997 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1996 Markus Franz Xaver Johannes Oberhumer + All Rights Reserved. + + The LZO library 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. + + The LZO library 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 the LZO library; see the file COPYING. + If not, write to the Free Software Foundation, Inc., + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + + Markus F.X.J. Oberhumer + <ma...@ob...> + http://www.oberhumer.com/opensource/lzo/ + + + This file was derived from several header files found in original + LZO 2.02 code. Some additional changes have also been made to make + it work in kernel space. + + Nitin Gupta + <nit...@gm...> + */ + +#ifndef __LZO1X_INT_H +#define __LZO1X_INT_H + +#include <linux/types.h> + +#define D_SIZE (1u << D_BITS) +#define D_MASK (D_SIZE - 1) +#define D_HIGH ((D_MASK >> 1) + 1) + +#define DX2(p,s1,s2) \ + (((((size_t)((p)[2]) << (s2)) ^ (p)[1]) << (s1)) ^ (p)[0]) +#define DX3(p,s1,s2,s3) ((DX2((p)+1,s2,s3) << (s1)) ^ (p)[0]) +#define DMUL(a,b) ((size_t) ((a) * (b))) +#define DMS(v,s) ((size_t) (((v) & (D_MASK >> (s))) << (s))) +#define DM(v) DMS(v,0) + +#define D_BITS 14 +#define DINDEX1(d,p) d = DM(DMUL(0x21,DX3(p,5,5,6)) >> 5) +#define DINDEX2(d,p) d = (d & (D_MASK & 0x7ff)) ^ (D_HIGH | 0x1f) +#define DENTRY(p,in) (p) + +#define PTR(a) ((unsigned long) (a)) +#define PTR_LT(a,b) (PTR(a) < PTR(b)) +#define PTR_GE(a,b) (PTR(a) >= PTR(b)) +#define PTR_DIFF(a,b) (PTR(a) - PTR(b)) +#define pd(a,b) ((size_t) ((a)-(b))) + +#define LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,max_offset) \ + ( m_pos = ip - (size_t) PTR_DIFF(ip,m_pos), \ + PTR_LT(m_pos,in) || \ + (m_off = (size_t) PTR_DIFF(ip,m_pos)) <= 0 || \ + m_off > max_offset ) + +#define COPY4(dst,src) *(size_t *)(dst) = *(size_t *)(src) + + +/* LZO1X Specific constants */ + +#define M1_MAX_OFFSET 0x0400 +#define M2_MAX_OFFSET 0x0800 +#define M3_MAX_OFFSET 0x4000 +#define M4_MAX_OFFSET 0xbfff + +#define MX_MAX_OFFSET (M1_MAX_OFFSET + M2_MAX_OFFSET) + +#define M1_MIN_LEN 2 +#define M1_MAX_LEN 2 +#define M2_MIN_LEN 3 +#define M2_MAX_LEN 8 +#define M3_MIN_LEN 3 +#define M3_MAX_LEN 33 +#define M4_MIN_LEN 3 +#define M4_MAX_LEN 9 + +#define M1_MARKER 0 +#define M2_MARKER 64 +#define M3_MARKER 32 +#define M4_MARKER 16 + +#define MIN_LOOKAHEAD (M2_MAX_LEN + 1) + +#endif /* already included */ |
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From: Nitin G. <nit...@gm...> - 2007-05-14 12:57:53
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This is the LZO1X-1 compression code. Signed-off-by: Nitin Gupta <nit...@gm...> Index: linux-cc/lib/lzo1x/lzo1x_compress.c =================================================================== --- /dev/null +++ linux-cc/lib/lzo1x/lzo1x_compress.c @@ -0,0 +1,284 @@ +/* lzo1x_compress.c -- LZO1X-1 compression + + This file is part of the LZO real-time data compression library. + + Copyright (C) 2005 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2004 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2003 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2002 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2001 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2000 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1999 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1998 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1997 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1996 Markus Franz Xaver Johannes Oberhumer + All Rights Reserved. + + The LZO library 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. + + The LZO library 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 the LZO library; see the file COPYING. + If not, write to the Free Software Foundation, Inc., + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + + Markus F.X.J. Oberhumer + <ma...@ob...> + http://www.oberhumer.com/opensource/lzo/ + + + This file is derived from lzo1x_1.c and lzo1x_c.ch found in original + LZO 2.02 code. Some additional changes have also been made to make + it work in kernel space. + + Nitin Gupta + <nit...@gm...> + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/compiler.h> + +#include "lzo1x_int.h" + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("LZO1X Compression"); + +/*********************************************************************** +// compress a block of data. +************************************************************************/ + +static unsigned int +lzo1x_compress_worker(const unsigned char *in, size_t in_len, + unsigned char *out, size_t *out_len, + void *workmem) +{ + register const unsigned char *ip; + unsigned char *op; + 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 *ii; + const unsigned char ** const dict = (const unsigned char **)workmem; + + op = out; + ip = in; + ii = ip; + + ip += 4; + for (;;) + { + register const unsigned char *m_pos; + size_t m_off; + size_t m_len; + size_t dindex; + + DINDEX1(dindex,ip); + m_pos = dict[dindex]; + if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M4_MAX_OFFSET)) + goto literal; + if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3]) + goto try_match; + DINDEX2(dindex,ip); + + m_pos = dict[dindex]; + if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M4_MAX_OFFSET)) + goto literal; + if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3]) + goto try_match; + goto literal; + + +try_match: + if (*(const unsigned short *)m_pos != *(const unsigned short *)ip) + { + } + else + { + if (likely(m_pos[2] == ip[2])) + goto match; + } + + /* a literal */ +literal: + dict[dindex] = ip; + ++ip; + if (unlikely(ip >= ip_end)) + break; + continue; + + + /* a match */ +match: + dict[dindex] = ip; + /* store current literal run */ + if (pd(ip,ii) > 0) + { + register size_t t = pd(ip,ii); + + if (t <= 3) + { + op[-2] |= (unsigned char)(t); + } + else if (t <= 18) + *op++ = (unsigned char)(t - 3); + else + { + register size_t tt = t - 18; + + *op++ = 0; + while (tt > 255) + { + tt -= 255; + *op++ = 0; + } + *op++ = (unsigned char)(tt); + } + do *op++ = *ii++; while (--t > 0); + } + + /* code the match */ + 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 = pd(ip, ii); + + if (m_off <= M2_MAX_OFFSET) + { + m_off -= 1; + *op++ = (unsigned char)(((m_len - 1) << 5) | ((m_off & 7) << 2)); + *op++ = (unsigned char)(m_off >> 3); + } + else if (m_off <= M3_MAX_OFFSET) + { + m_off -= 1; + *op++ = (unsigned char)(M3_MARKER | (m_len - 2)); + goto m3_m4_offset; + } + else + { + m_off -= 0x4000; + *op++ = (unsigned char)(M4_MARKER | + ((m_off & 0x4000) >> 11) | (m_len - 2)); + goto m3_m4_offset; + } + } + else + { + { + const unsigned char *end = in_end; + const unsigned char *m = m_pos + M2_MAX_LEN + 1; + while (ip < end && *m == *ip) + m++, ip++; + m_len = pd(ip, ii); + } + + if (m_off <= M3_MAX_OFFSET) + { + m_off -= 1; + if (m_len <= 33) + *op++ = (unsigned char)(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++ = (unsigned char)(M4_MARKER | + ((m_off & 0x4000) >> 11) | (m_len - 2)); + else + { + m_len -= M4_MAX_LEN; + *op++ = (unsigned char)(M4_MARKER | ((m_off & 0x4000) >> 11)); +m3_m4_len: + while (m_len > 255) + { + m_len -= 255; + *op++ = 0; + } + *op++ = (unsigned char)(m_len); + } + } + +m3_m4_offset: + *op++ = (unsigned char)((m_off & 63) << 2); + *op++ = (unsigned char)(m_off >> 6); + } + + ii = ip; + if (unlikely(ip >= ip_end)) + break; + } + + *out_len = pd(op, out); + return pd(in_end,ii); +} + + +/*********************************************************************** +// public entry point +************************************************************************/ + +int +lzo1x_compress(const unsigned char *in, size_t in_len, + unsigned char *out, size_t *out_len, + void *workmem) +{ + unsigned char *op = out; + size_t t; + + if (unlikely(in_len <= M2_MAX_LEN + 5)) + t = in_len; + else + { + t = lzo1x_compress_worker(in,in_len,op,out_len,workmem); + op += *out_len; + } + + if (t > 0) + { + const unsigned char *ii = in + in_len - t; + + if (op == out && t <= 238) + *op++ = (unsigned char)(17 + t); + else if (t <= 3) + op[-2] |= (unsigned char)(t); + else if (t <= 18) + *op++ = (unsigned char)(t - 3); + else + { + size_t tt = t - 18; + + *op++ = 0; + while (tt > 255) + { + tt -= 255; + *op++ = 0; + } + *op++ = (unsigned char)(tt); + } + do *op++ = *ii++; while (--t > 0); + } + + *op++ = M4_MARKER | 1; + *op++ = 0; + *op++ = 0; + + *out_len = pd(op, out); + return 0; +} + +EXPORT_SYMBOL(lzo1x_compress); |
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From: Nitin G. <nit...@gm...> - 2007-05-14 12:59:05
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This is LZO decompression code. Signed-off-by: Nitin Gupta <nit...@gm...> Index: linux-cc/lib/lzo1x/lzo1x_decompress.c =================================================================== --- /dev/null +++ linux-cc/lib/lzo1x/lzo1x_decompress.c @@ -0,0 +1,226 @@ +/* lzo1x_decompress.c -- LZO1X decompression + + This file is part of the LZO real-time data compression library. + + Copyright (C) 2005 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2004 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2003 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2002 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2001 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2000 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1999 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1998 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1997 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 1996 Markus Franz Xaver Johannes Oberhumer + All Rights Reserved. + + The LZO library 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. + + The LZO library 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 the LZO library; see the file COPYING. + If not, write to the Free Software Foundation, Inc., + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + + Markus F.X.J. Oberhumer + <ma...@ob...> + http://www.oberhumer.com/opensource/lzo/ + + + This file is derived from lzo1x_d1.c and lzo1x_d.ch found in original + LZO 2.02 code. Some additional changes have also been made to make + it work in kernel space. + + Nitin Gupta + <nit...@gm...> + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <asm/byteorder.h> + +#include "lzo1x_int.h" + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("LZO1X Decompression"); + +/*********************************************************************** +// decompress a block of data. +************************************************************************/ + +int +lzo1x_decompress(const unsigned char *in, size_t in_len, + unsigned char *out, size_t *out_len) +{ + register size_t t; + register unsigned char *op; + register const unsigned char *ip, *m_pos; + const unsigned char * const ip_end = in + in_len; + + *out_len = 0; + + op = out; + ip = in; + + if (*ip > 17) + { + t = *ip++ - 17; + if (t < 4) + goto match_next; + do *op++ = *ip++; while (--t > 0); + goto first_literal_run; + } + + while (1) + { + t = *ip++; + if (t >= 16) + goto match; + /* a literal run */ + if (t == 0) + { + while (*ip == 0) + { + t += 255; + ip++; + } + t += 15 + *ip++; + } + /* copy literals */ + COPY4(op,ip); + op += 4; ip += 4; + if (--t > 0) + { + if (t >= 4) + { + do { + COPY4(op,ip); + op += 4; ip += 4; t -= 4; + } while (t >= 4); + if (t > 0) do *op++ = *ip++; while (--t > 0); + } + else + do *op++ = *ip++; while (--t > 0); + } + +first_literal_run: + + + t = *ip++; + if (t >= 16) + goto match; + m_pos = op - (1 + M2_MAX_OFFSET); + m_pos -= t >> 2; + m_pos -= *ip++ << 2; + *op++ = *m_pos++; *op++ = *m_pos++; *op++ = *m_pos; + goto match_done; + + + /* handle matches */ + do { +match: + if (t >= 64) /* a M2 match */ + { + m_pos = op - 1; + m_pos -= (t >> 2) & 7; + m_pos -= *ip++ << 3; + t = (t >> 5) - 1; + goto copy_match; + } + else if (t >= 32) /* a M3 match */ + { + t &= 31; + if (t == 0) + { + while (*ip == 0) + { + t += 255; + ip++; + } + t += 31 + *ip++; + } +#if defined(__LITTLE_ENDIAN) + m_pos = op - 1; + m_pos -= (*(const unsigned short *)ip) >> 2; +#else + m_pos = op - 1; + m_pos -= (ip[0] >> 2) + (ip[1] << 6); +#endif + ip += 2; + } + else if (t >= 16) /* a M4 match */ + { + m_pos = op; + m_pos -= (t & 8) << 11; + t &= 7; + if (t == 0) + { + while (*ip == 0) + { + t += 255; + ip++; + } + t += 7 + *ip++; + } +#if defined(__LITTLE_ENDIAN) + m_pos -= (*(const unsigned short *)ip) >> 2; +#else + m_pos -= (ip[0] >> 2) + (ip[1] << 6); +#endif + ip += 2; + if (m_pos == op) + goto eof_found; + m_pos -= 0x4000; + } + else /* a M1 match */ + { + m_pos = op - 1; + m_pos -= t >> 2; + m_pos -= *ip++ << 2; + *op++ = *m_pos++; *op++ = *m_pos; + goto match_done; + } + + /* copy match */ + if (t >= 2 * 4 - (3 - 1) && (op - m_pos) >= 4) + { + COPY4(op,m_pos); + op += 4; m_pos += 4; t -= 4 - (3 - 1); + do { + COPY4(op,m_pos); + op += 4; m_pos += 4; t -= 4; + } while (t >= 4); + if (t > 0) do *op++ = *m_pos++; while (--t > 0); + } + else + { +copy_match: + *op++ = *m_pos++; *op++ = *m_pos++; + do *op++ = *m_pos++; while (--t > 0); + } + +match_done: + t = ip[-2] & 3; + if (t == 0) + break; + + /* copy literals */ +match_next: + *op++ = *ip++; + if (t > 1) { *op++ = *ip++; if (t > 2) { *op++ = *ip++; } } + t = *ip++; + } while (1); + } + +eof_found: + *out_len = pd(op, out); + return (ip == ip_end ? 0 : -1); +} + +EXPORT_SYMBOL(lzo1x_decompress); |
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From: Nitin G. <nit...@gm...> - 2007-05-14 12:53:14
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This adds LZO1X as config option in kernel and does Makefile changes to add it as additional target. Signed-off-by: Nitin Gupta <nit...@gm...> Index: linux-cc/lib/Kconfig =================================================================== --- linux-cc.orig/lib/Kconfig +++ linux-cc/lib/Kconfig @@ -64,6 +64,9 @@ config ZLIB_INFLATE config ZLIB_DEFLATE tristate +config LZO1X + tristate "LZO1X Compression/Decompression" + # # Generic allocator support is selected if needed # Index: linux-cc/lib/Makefile =================================================================== --- linux-cc.orig/lib/Makefile +++ linux-cc/lib/Makefile @@ -49,6 +49,7 @@ obj-$(CONFIG_GENERIC_ALLOCATOR) += genal obj-$(CONFIG_ZLIB_INFLATE) += zlib_inflate/ obj-$(CONFIG_ZLIB_DEFLATE) += zlib_deflate/ obj-$(CONFIG_REED_SOLOMON) += reed_solomon/ +obj-$(CONFIG_LZO1X) += lzo1x/ obj-$(CONFIG_TEXTSEARCH) += textsearch.o obj-$(CONFIG_TEXTSEARCH_KMP) += ts_kmp.o Index: linux-cc/lib/lzo1x/Makefile =================================================================== --- /dev/null +++ linux-cc/lib/lzo1x/Makefile @@ -0,0 +1,2 @@ +obj-$(CONFIG_LZO1X) += lzo1x.o +lzo1x-objs := lzo1x_compress.o lzo1x_decompress.o |
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From: Nitin G. <nit...@gm...> - 2007-05-15 10:06:45
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Hi, On 5/14/07, Richard Purdie <ri...@op...> wrote: > * The safe decompression version of the decompress function is missing. > Ideally we should have that as I suspect most kernel use cases should be > doing bounds checking. I did wonder if we should have bounds checking in > the compression case too although its less significant from a security > PoV. > I think the "safe" decompress version is only required when we suspect that compressed data might be corrupted. Otherwise, if such data corruption is not possible then this "unsafe" decompress will never overrun output buffer -- since output buffer lenght is not used by unsafe version but still it should never exceed buffer size beyoond original data size. I think I should contact the author to make sure I am correct here... Also "safe" decompress will obviously have perf penalties too. But anyhow adding option for have safe decompress is worth it. > * The code doesn't conform to CodingStyle as tabs aren't used for > indentation for a start and the brackets don't conform either. > > * For a better version of the include/linux/lzo1x.h header file see my > include/linux/lzo.h patch which includes error codes and maximum > compression size defines. > > * My patch series adds crypto layer support which might be useful for > testing > > * The patch series will need to be merged into one patch for submission > to mainline since its all interdependent. > > Just to confirm, this code is 100% compatible with data compressed with > LZO's lzo1x_compress function? > > I suspect there is some hybrid between the two versions which would be > ideal! :) > > Cheers, > > Richard > > |
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From: Nitin G. <nit...@gm...> - 2007-05-15 10:13:07
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> > > * The code doesn't conform to CodingStyle as tabs aren't used for > > indentation for a start and the brackets don't conform either. > > I am now done will all formatting - will post newer version (as single patch) soon. > > * For a better version of the include/linux/lzo1x.h header file see my > > include/linux/lzo.h patch which includes error codes and maximum > > compression size defines. > > I could not see any use for those LZO error codes (like LZO_E_OK). Simple return value of 0 (success) and -1 (error) look fine. > > * My patch series adds crypto layer support which might be useful for > > testing > > For now, I am just looking at plain LZO algo... > > * The patch series will need to be merged into one patch for submission > > to mainline since its all interdependent. Yes. I did that splitting only for easier reviewing. I will post that as single patch soon. > > > > Just to confirm, this code is 100% compatible with data compressed with > > LZO's lzo1x_compress function? > > Yes. > > I suspect there is some hybrid between the two versions which would be > > ideal! :) > > I don't know :-) Cheers, Nitin |
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