| /* |
| * Copyright (c) 2000-2010 Marc Alexander Lehmann <[email protected]> |
| * |
| * Redistribution and use in source and binary forms, with or without modifica- |
| * tion, are permitted provided that the following conditions are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright notice, |
| * this list of conditions and the following disclaimer. |
| * |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER- |
| * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO |
| * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE- |
| * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; |
| * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
| * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH- |
| * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
| * OF THE POSSIBILITY OF SUCH DAMAGE. |
| * |
| * Alternatively, the contents of this file may be used under the terms of |
| * the GNU General Public License ("GPL") version 2 or any later version, |
| * in which case the provisions of the GPL are applicable instead of |
| * the above. If you wish to allow the use of your version of this file |
| * only under the terms of the GPL and not to allow others to use your |
| * version of this file under the BSD license, indicate your decision |
| * by deleting the provisions above and replace them with the notice |
| * and other provisions required by the GPL. If you do not delete the |
| * provisions above, a recipient may use your version of this file under |
| * either the BSD or the GPL. |
| */ |
| |
| #include "lzfP.h" |
| |
| #define HSIZE (1 << (HLOG)) |
| |
| /* |
| * don't play with this unless you benchmark! |
| * the data format is not dependent on the hash function. |
| * the hash function might seem strange, just believe me, |
| * it works ;) |
| */ |
| #ifndef FRST |
| # define FRST(p) (((p[0]) << 8) | p[1]) |
| # define NEXT(v,p) (((v) << 8) | p[2]) |
| # if ULTRA_FAST |
| # define IDX(h) ((( h >> (3*8 - HLOG)) - h ) & (HSIZE - 1)) |
| # elif VERY_FAST |
| # define IDX(h) ((( h >> (3*8 - HLOG)) - h*5) & (HSIZE - 1)) |
| # else |
| # define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1)) |
| # endif |
| #endif |
| /* |
| * IDX works because it is very similar to a multiplicative hash, e.g. |
| * ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1)) |
| * the latter is also quite fast on newer CPUs, and compresses similarly. |
| * |
| * the next one is also quite good, albeit slow ;) |
| * (int)(cos(h & 0xffffff) * 1e6) |
| */ |
| |
| #if 0 |
| /* original lzv-like hash function, much worse and thus slower */ |
| # define FRST(p) (p[0] << 5) ^ p[1] |
| # define NEXT(v,p) ((v) << 5) ^ p[2] |
| # define IDX(h) ((h) & (HSIZE - 1)) |
| #endif |
| |
| #define MAX_LIT (1 << 5) |
| #define MAX_OFF (1 << 13) |
| #define MAX_REF ((1 << 8) + (1 << 3)) |
| |
| #if __GNUC__ >= 3 |
| # define expect(expr,value) __builtin_expect ((expr),(value)) |
| # define inline inline |
| #else |
| # define expect(expr,value) (expr) |
| # define inline static |
| #endif |
| |
| #define expect_false(expr) expect ((expr) != 0, 0) |
| #define expect_true(expr) expect ((expr) != 0, 1) |
| |
| /* |
| * compressed format |
| * |
| * 000LLLLL <L+1> ; literal, L+1=1..33 octets |
| * LLLooooo oooooooo ; backref L+1=1..7 octets, o+1=1..4096 offset |
| * 111ooooo LLLLLLLL oooooooo ; backref L+8 octets, o+1=1..4096 offset |
| * |
| */ |
| |
| unsigned int |
| lzf_compress (const void *const in_data, unsigned int in_len, |
| void *out_data, unsigned int out_len |
| #if LZF_STATE_ARG |
| , LZF_STATE htab |
| #endif |
| ) |
| { |
| #if !LZF_STATE_ARG |
| LZF_STATE htab; |
| #endif |
| const u8 *ip = (const u8 *)in_data; |
| u8 *op = (u8 *)out_data; |
| const u8 *in_end = ip + in_len; |
| u8 *out_end = op + out_len; |
| const u8 *ref; |
| |
| /* off requires a type wide enough to hold a general pointer difference. |
| * ISO C doesn't have that (size_t might not be enough and ptrdiff_t only |
| * works for differences within a single object). We also assume that no |
| * no bit pattern traps. Since the only platform that is both non-POSIX |
| * and fails to support both assumptions is windows 64 bit, we make a |
| * special workaround for it. |
| */ |
| #if defined (WIN32) && defined (_M_X64) |
| unsigned _int64 off; /* workaround for missing POSIX compliance */ |
| #else |
| unsigned long off; |
| #endif |
| unsigned int hval; |
| int lit; |
| |
| if (!in_len || !out_len) |
| return 0; |
| |
| #if INIT_HTAB |
| memset (htab, 0, sizeof (htab)); |
| #endif |
| |
| lit = 0; op++; /* start run */ |
| |
| hval = FRST (ip); |
| while (ip < in_end - 2) |
| { |
| LZF_HSLOT *hslot; |
| |
| hval = NEXT (hval, ip); |
| hslot = htab + IDX (hval); |
| ref = *hslot + LZF_HSLOT_BIAS; *hslot = ip - LZF_HSLOT_BIAS; |
| |
| if (1 |
| #if INIT_HTAB |
| && ref < ip /* the next test will actually take care of this, but this is faster */ |
| #endif |
| && (off = ip - ref - 1) < MAX_OFF |
| && ref > (u8 *)in_data |
| && ref[2] == ip[2] |
| #if STRICT_ALIGN |
| && ((ref[1] << 8) | ref[0]) == ((ip[1] << 8) | ip[0]) |
| #else |
| && *(u16 *)ref == *(u16 *)ip |
| #endif |
| ) |
| { |
| /* match found at *ref++ */ |
| unsigned int len = 2; |
| unsigned int maxlen = in_end - ip - len; |
| maxlen = maxlen > MAX_REF ? MAX_REF : maxlen; |
| |
| if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */ |
| if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */ |
| return 0; |
| |
| op [- lit - 1] = lit - 1; /* stop run */ |
| op -= !lit; /* undo run if length is zero */ |
| |
| for (;;) |
| { |
| if (expect_true (maxlen > 16)) |
| { |
| len++; if (ref [len] != ip [len]) break; |
| len++; if (ref [len] != ip [len]) break; |
| len++; if (ref [len] != ip [len]) break; |
| len++; if (ref [len] != ip [len]) break; |
| |
| len++; if (ref [len] != ip [len]) break; |
| len++; if (ref [len] != ip [len]) break; |
| len++; if (ref [len] != ip [len]) break; |
| len++; if (ref [len] != ip [len]) break; |
| |
| len++; if (ref [len] != ip [len]) break; |
| len++; if (ref [len] != ip [len]) break; |
| len++; if (ref [len] != ip [len]) break; |
| len++; if (ref [len] != ip [len]) break; |
| |
| len++; if (ref [len] != ip [len]) break; |
| len++; if (ref [len] != ip [len]) break; |
| len++; if (ref [len] != ip [len]) break; |
| len++; if (ref [len] != ip [len]) break; |
| } |
| |
| do |
| len++; |
| while (len < maxlen && ref[len] == ip[len]); |
| |
| break; |
| } |
| |
| len -= 2; /* len is now #octets - 1 */ |
| ip++; |
| |
| if (len < 7) |
| { |
| *op++ = (off >> 8) + (len << 5); |
| } |
| else |
| { |
| *op++ = (off >> 8) + ( 7 << 5); |
| *op++ = len - 7; |
| } |
| |
| *op++ = off; |
| |
| lit = 0; op++; /* start run */ |
| |
| ip += len + 1; |
| |
| if (expect_false (ip >= in_end - 2)) |
| break; |
| |
| #if ULTRA_FAST || VERY_FAST |
| --ip; |
| # if VERY_FAST && !ULTRA_FAST |
| --ip; |
| # endif |
| hval = FRST (ip); |
| |
| hval = NEXT (hval, ip); |
| htab[IDX (hval)] = ip - LZF_HSLOT_BIAS; |
| ip++; |
| |
| # if VERY_FAST && !ULTRA_FAST |
| hval = NEXT (hval, ip); |
| htab[IDX (hval)] = ip - LZF_HSLOT_BIAS; |
| ip++; |
| # endif |
| #else |
| ip -= len + 1; |
| |
| do |
| { |
| hval = NEXT (hval, ip); |
| htab[IDX (hval)] = ip - LZF_HSLOT_BIAS; |
| ip++; |
| } |
| while (len--); |
| #endif |
| } |
| else |
| { |
| /* one more literal byte we must copy */ |
| if (expect_false (op >= out_end)) |
| return 0; |
| |
| lit++; *op++ = *ip++; |
| |
| if (expect_false (lit == MAX_LIT)) |
| { |
| op [- lit - 1] = lit - 1; /* stop run */ |
| lit = 0; op++; /* start run */ |
| } |
| } |
| } |
| |
| if (op + 3 > out_end) /* at most 3 bytes can be missing here */ |
| return 0; |
| |
| while (ip < in_end) |
| { |
| lit++; *op++ = *ip++; |
| |
| if (expect_false (lit == MAX_LIT)) |
| { |
| op [- lit - 1] = lit - 1; /* stop run */ |
| lit = 0; op++; /* start run */ |
| } |
| } |
| |
| op [- lit - 1] = lit - 1; /* end run */ |
| op -= !lit; /* undo run if length is zero */ |
| |
| return op - (u8 *)out_data; |
| } |
| |
