/* * Copyright (c) 2000-2008 Marc Alexander Lehmann * * 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! * decompression is not dependent on the hash function * the hashing 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 ; literal * LLLooooo oooooooo ; backref L * 111ooooo LLLLLLLL oooooooo ; backref L+7 * */ 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 **hslot; 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 long long 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)); # if 0 for (hslot = htab; hslot < htab + HSIZE; hslot++) *hslot++ = ip; # endif #endif lit = 0; op++; /* start run */ hval = FRST (ip); while (ip < in_end - 2) { hval = NEXT (hval, ip); hslot = htab + IDX (hval); ref = *hslot; *hslot = ip; 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 && ip + 4 < in_end && ref > (u8 *)in_data #if STRICT_ALIGN && ref[0] == ip[0] && ref[1] == ip[1] && ref[2] == ip[2] #else && *(u16 *)ref == *(u16 *)ip && ref[2] == ip[2] #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; ip++; # if VERY_FAST && !ULTRA_FAST hval = NEXT (hval, ip); htab[IDX (hval)] = ip; ip++; # endif #else ip -= len + 1; do { hval = NEXT (hval, ip); htab[IDX (hval)] = ip; 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; }