[lc-devel] [RFC] LZO de/compression support in kernel [5/5]
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[lc-devel] [RFC] LZO de/compression support in kernel [5/5]
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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); |
