296 lines
8.7 KiB
C
296 lines
8.7 KiB
C
/*
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* Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
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*
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* Redistribution and use in source and binary forms, with or without modifica-
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* tion, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
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* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
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* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
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* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Alternatively, the contents of this file may be used under the terms of
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* the GNU General Public License ("GPL") version 2 or any later version,
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* in which case the provisions of the GPL are applicable instead of
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* the above. If you wish to allow the use of your version of this file
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* only under the terms of the GPL and not to allow others to use your
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* version of this file under the BSD license, indicate your decision
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* by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL. If you do not delete the
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* provisions above, a recipient may use your version of this file under
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* either the BSD or the GPL.
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*/
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#include "lzfP.h"
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#define HSIZE (1 << (HLOG))
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/*
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* don't play with this unless you benchmark!
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* decompression is not dependent on the hash function
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* the hashing function might seem strange, just believe me
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* it works ;)
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*/
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#ifndef FRST
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# define FRST(p) (((p[0]) << 8) | p[1])
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# define NEXT(v,p) (((v) << 8) | p[2])
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# if ULTRA_FAST
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# define IDX(h) ((( h >> (3*8 - HLOG)) - h ) & (HSIZE - 1))
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# elif VERY_FAST
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# define IDX(h) ((( h >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
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# else
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# define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
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# endif
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#endif
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/*
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* IDX works because it is very similar to a multiplicative hash, e.g.
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* ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1))
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* the latter is also quite fast on newer CPUs, and compresses similarly.
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*
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* the next one is also quite good, albeit slow ;)
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* (int)(cos(h & 0xffffff) * 1e6)
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*/
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#if 0
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/* original lzv-like hash function, much worse and thus slower */
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# define FRST(p) (p[0] << 5) ^ p[1]
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# define NEXT(v,p) ((v) << 5) ^ p[2]
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# define IDX(h) ((h) & (HSIZE - 1))
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#endif
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#define MAX_LIT (1 << 5)
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#define MAX_OFF (1 << 13)
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#define MAX_REF ((1 << 8) + (1 << 3))
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#if __GNUC__ >= 3
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# define expect(expr,value) __builtin_expect ((expr),(value))
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# define inline inline
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#else
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# define expect(expr,value) (expr)
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# define inline static
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#endif
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#define expect_false(expr) expect ((expr) != 0, 0)
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#define expect_true(expr) expect ((expr) != 0, 1)
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/*
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* compressed format
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*
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* 000LLLLL <L+1> ; literal
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* LLLooooo oooooooo ; backref L
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* 111ooooo LLLLLLLL oooooooo ; backref L+7
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*
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*/
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unsigned int
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lzf_compress (const void *const in_data, unsigned int in_len,
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void *out_data, unsigned int out_len
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#if LZF_STATE_ARG
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, LZF_STATE htab
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#endif
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)
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{
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#if !LZF_STATE_ARG
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LZF_STATE htab;
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#endif
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const u8 **hslot;
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const u8 *ip = (const u8 *)in_data;
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u8 *op = (u8 *)out_data;
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const u8 *in_end = ip + in_len;
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u8 *out_end = op + out_len;
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const u8 *ref;
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/* off requires a type wide enough to hold a general pointer difference.
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* ISO C doesn't have that (size_t might not be enough and ptrdiff_t only
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* works for differences within a single object). We also assume that no
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* no bit pattern traps. Since the only platform that is both non-POSIX
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* and fails to support both assumptions is windows 64 bit, we make a
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* special workaround for it.
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*/
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#if defined (WIN32) && defined (_M_X64)
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unsigned _int64 off; /* workaround for missing POSIX compliance */
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#else
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unsigned long off;
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#endif
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unsigned int hval;
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int lit;
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if (!in_len || !out_len)
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return 0;
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#if INIT_HTAB
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memset (htab, 0, sizeof (htab));
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# if 0
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for (hslot = htab; hslot < htab + HSIZE; hslot++)
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*hslot++ = ip;
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# endif
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#endif
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lit = 0; op++; /* start run */
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hval = FRST (ip);
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while (ip < in_end - 2)
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{
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hval = NEXT (hval, ip);
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hslot = htab + IDX (hval);
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ref = *hslot; *hslot = ip;
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if (1
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#if INIT_HTAB
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&& ref < ip /* the next test will actually take care of this, but this is faster */
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#endif
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&& (off = ip - ref - 1) < MAX_OFF
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&& ip + 4 < in_end
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&& ref > (u8 *)in_data
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#if STRICT_ALIGN
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&& ref[0] == ip[0]
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&& ref[1] == ip[1]
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&& ref[2] == ip[2]
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#else
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&& *(u16 *)ref == *(u16 *)ip
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&& ref[2] == ip[2]
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#endif
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)
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{
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/* match found at *ref++ */
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unsigned int len = 2;
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unsigned int maxlen = in_end - ip - len;
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maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
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op [- lit - 1] = lit - 1; /* stop run */
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op -= !lit; /* undo run if length is zero */
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if (expect_false (op + 3 + 1 >= out_end))
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return 0;
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for (;;)
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{
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if (expect_true (maxlen > 16))
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{
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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len++; if (ref [len] != ip [len]) break;
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}
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do
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len++;
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while (len < maxlen && ref[len] == ip[len]);
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break;
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}
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len -= 2; /* len is now #octets - 1 */
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ip++;
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if (len < 7)
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{
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*op++ = (off >> 8) + (len << 5);
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}
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else
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{
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*op++ = (off >> 8) + ( 7 << 5);
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*op++ = len - 7;
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}
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*op++ = off;
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lit = 0; op++; /* start run */
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ip += len + 1;
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if (expect_false (ip >= in_end - 2))
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break;
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#if ULTRA_FAST || VERY_FAST
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--ip;
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# if VERY_FAST && !ULTRA_FAST
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--ip;
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# endif
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hval = FRST (ip);
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hval = NEXT (hval, ip);
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htab[IDX (hval)] = ip;
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ip++;
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# if VERY_FAST && !ULTRA_FAST
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hval = NEXT (hval, ip);
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htab[IDX (hval)] = ip;
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ip++;
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# endif
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#else
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ip -= len + 1;
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do
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{
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hval = NEXT (hval, ip);
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htab[IDX (hval)] = ip;
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ip++;
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}
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while (len--);
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#endif
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}
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else
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{
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/* one more literal byte we must copy */
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if (expect_false (op >= out_end))
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return 0;
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lit++; *op++ = *ip++;
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if (expect_false (lit == MAX_LIT))
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{
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op [- lit - 1] = lit - 1; /* stop run */
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lit = 0; op++; /* start run */
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}
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}
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}
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if (op + 3 > out_end) /* at most 3 bytes can be missing here */
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return 0;
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while (ip < in_end)
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{
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lit++; *op++ = *ip++;
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if (expect_false (lit == MAX_LIT))
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{
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op [- lit - 1] = lit - 1; /* stop run */
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lit = 0; op++; /* start run */
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}
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}
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op [- lit - 1] = lit - 1; /* end run */
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op -= !lit; /* undo run if length is zero */
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return op - (u8 *)out_data;
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}
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