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Copy pathCompress.cpp
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338 lines (276 loc) · 7.53 KB
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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
*/
#include "stdafx.h"
#include "Compress.h"
#include "../zlib/zlib.h"
#define NBBY 8
#define MATCH_BITS 6
#define MATCH_MIN 3
#define MATCH_MAX ((1 << MATCH_BITS) + (MATCH_MIN - 1))
#define OFFSET_MASK ((1 << (16 - MATCH_BITS)) - 1)
#define LEMPEL_SIZE 1024
/*
* We keep our own copy of this algorithm for 3 main reasons:
* 1. If we didn't, anyone modifying common/os/compress.c would
* directly break our on disk format
* 2. Our version of lzjb does not have a number of checks that the
* common/os version needs and uses
* 3. We initialize the lempel to ensure deterministic results,
* so that identical blocks can always be deduplicated.
* In particular, we are adding the "feature" that compress() can
* take a destination buffer size and returns the compressed length, or the
* source length if compression would overflow the destination buffer.
*/
size_t lzjb_compress(void* s_start, void* d_start, size_t s_len, size_t d_len, int n)
{
uint8_t* src = (uint8_t*)s_start;
uint8_t* dst = (uint8_t*)d_start;
uint8_t* cpy;
uint8_t* copymap;
int copymask = 1 << (NBBY - 1);
int mlen, offset, hash;
uint16_t* hp;
uint16_t lempel[LEMPEL_SIZE] = { 0 };
while(src < (uint8_t*)s_start + s_len)
{
if((copymask <<= 1) == (1 << NBBY))
{
if(dst >= (uint8_t *)d_start + d_len - 1 - 2 * NBBY)
{
return s_len;
}
copymask = 1;
copymap = dst;
*dst++ = 0;
}
if(src > (uint8_t*)s_start + s_len - MATCH_MAX)
{
*dst++ = *src++;
continue;
}
hash = (src[0] << 16) + (src[1] << 8) + src[2];
hash += hash >> 9;
hash += hash >> 5;
hp = &lempel[hash & (LEMPEL_SIZE - 1)];
offset = (intptr_t)(src - *hp) & OFFSET_MASK;
*hp = (uint16_t)(uintptr_t)src;
cpy = src - offset;
if(cpy >= (uint8_t *)s_start && cpy != src && src[0] == cpy[0] && src[1] == cpy[1] && src[2] == cpy[2])
{
*copymap |= copymask;
for(mlen = MATCH_MIN; mlen < MATCH_MAX; mlen++)
{
if(src[mlen] != cpy[mlen])
{
break;
}
}
*dst++ = ((mlen - MATCH_MIN) << (NBBY - MATCH_BITS)) | (offset >> NBBY);
*dst++ = (uint8_t)offset;
src += mlen;
}
else
{
*dst++ = *src++;
}
}
return dst - (uint8_t*)d_start;
}
int lzjb_decompress(void* s_start, void* d_start, size_t s_len, size_t d_len)
{
uint8_t* src = (uint8_t*)s_start;
uint8_t* dst = (uint8_t*)d_start;
uint8_t* d_end = (uint8_t*)d_start + d_len;
uint8_t* cpy;
uint8_t copymap;
int copymask = 1 << (NBBY - 1);
while(dst < d_end)
{
if((copymask <<= 1) == (1 << NBBY))
{
copymask = 1;
copymap = *src++;
}
if(copymap & copymask)
{
int mlen = (src[0] >> (NBBY - MATCH_BITS)) + MATCH_MIN;
int offset = ((src[0] << NBBY) | src[1]) & OFFSET_MASK;
src += 2;
if((cpy = dst - offset) < (uint8_t*)d_start)
{
return -1;
}
while(--mlen >= 0 && dst < d_end)
{
*dst++ = *cpy++;
}
}
else
{
*dst++ = *src++;
}
}
return 0;
}
size_t gzip_compress(void* s_start, void* d_start, size_t s_len, size_t d_len, int n)
{
size_t dstlen = d_len;
ASSERT(d_len <= s_len);
uLongf len = dstlen;
if(compress2((Bytef*)d_start, &len, (Bytef*)s_start, s_len, n) != Z_OK)
{
if(d_len != s_len)
{
return s_len;
}
memcpy(s_start, d_start, s_len);
return s_len;
}
dstlen = len;
return dstlen;
}
int gzip_decompress(void* s_start, void* d_start, size_t s_len, size_t d_len)
{
size_t dstlen = d_len;
ASSERT(d_len >= s_len);
uLongf len = dstlen;
if(uncompress((Bytef*)d_start, &len, (Bytef*)s_start, s_len) != Z_OK)
{
return -1;
}
dstlen = len;
return 0;
}
/*
* Zero-length encoding. This is a fast and simple algorithm to eliminate
* runs of zeroes. Each chunk of compressed data begins with a length byte, b.
* If b < n (where n is the compression parameter) then the next b + 1 bytes
* are literal values. If b >= n then the next (256 - b + 1) bytes are zero.
*/
size_t zle_compress(void* s_start, void* d_start, size_t s_len, size_t d_len, int n)
{
uint8_t* src = (uint8_t*)s_start;
uint8_t* dst = (uint8_t*)d_start;
uint8_t* s_end = src + s_len;
uint8_t* d_end = dst + d_len;
while(src < s_end && dst < d_end - 1)
{
uint8_t* first = src;
uint8_t* len = dst++;
if(src[0] == 0)
{
uint8_t* last = src + (256 - n);
while(src < std::min<uint8_t*>(last, s_end) && src[0] == 0)
{
src++;
}
*len = src - first - 1 + n;
}
else
{
uint8_t* last = src + n;
if(d_end - dst < n)
{
break;
}
while(src < std::min<uint8_t*>(last, s_end) - 1 && (src[0] | src[1]))
{
*dst++ = *src++;
}
if(src[0])
{
*dst++ = *src++;
}
*len = src - first - 1;
}
}
return src == s_end ? dst - (uint8_t*)d_start : s_len;
}
int zle_decompress_64(void* s_start, void* d_start, size_t s_len, size_t d_len)
{
const int n = 64;
uint8_t* src = (uint8_t*)s_start;
uint8_t* dst = (uint8_t*)d_start;
uint8_t* s_end = src + s_len;
uint8_t* d_end = dst + d_len;
while(src < s_end && dst < d_end)
{
int len = 1 + *src++;
if(len <= n)
{
while(len-- != 0)
{
*dst++ = *src++;
}
}
else
{
len -= n;
while(len-- != 0)
{
*dst++ = 0;
}
}
}
return dst == d_end ? 0 : -1;
}
int copy_decompress(void* s_start, void* d_start, size_t s_len, size_t d_len)
{
ASSERT(s_len == d_len);
size_t size = std::min<size_t>(s_len, d_len);
memcpy(d_start, s_start, size);
return size;
}
typedef int (*decompress_func_t)(void* s_start, void* d_start, size_t s_len, size_t d_len);
static decompress_func_t s_decompress_func[] =
{
NULL, // ZIO_COMPRESS_INHERIT
lzjb_decompress, // ZIO_COMPRESS_ON
copy_decompress, // ZIO_COMPRESS_OFF
lzjb_decompress, // ZIO_COMPRESS_LZJB
NULL, // ZIO_COMPRESS_EMPTY
gzip_decompress, // ZIO_COMPRESS_GZIP_1
gzip_decompress, // ZIO_COMPRESS_GZIP_2
gzip_decompress, // ZIO_COMPRESS_GZIP_3
gzip_decompress, // ZIO_COMPRESS_GZIP_4
gzip_decompress, // ZIO_COMPRESS_GZIP_5
gzip_decompress, // ZIO_COMPRESS_GZIP_6
gzip_decompress, // ZIO_COMPRESS_GZIP_7
gzip_decompress, // ZIO_COMPRESS_GZIP_8
gzip_decompress, // ZIO_COMPRESS_GZIP_9
zle_decompress_64, // ZIO_COMPRESS_ZLE
};
bool ZFS::decompress(void* src, void* dst, size_t psize, size_t lsize, uint8_t comp_type)
{
if(comp_type < sizeof(s_decompress_func) / sizeof(s_decompress_func[0]))
{
decompress_func_t f = s_decompress_func[comp_type];
if(f != NULL)
{
f(src, dst, psize, lsize);
return true;
}
}
return false;
}