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Diffstat (limited to 'src/lzf_c.c')
| -rw-r--r-- | src/lzf_c.c | 302 |
1 files changed, 302 insertions, 0 deletions
diff --git a/src/lzf_c.c b/src/lzf_c.c new file mode 100644 index 0000000..7cbbc82 --- /dev/null +++ b/src/lzf_c.c @@ -0,0 +1,302 @@ +/* + * Copyright (c) 2000-2010 Marc Alexander Lehmann <schmorp@schmorp.de> + * + * 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) + +#if defined(__has_attribute) +# if __has_attribute(no_sanitize) +# define NO_SANITIZE(sanitizer) __attribute__((no_sanitize(sanitizer))) +# endif +#endif + +#if !defined(NO_SANITIZE) +# define NO_SANITIZE(sanitizer) +#endif + +/* + * 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 + * + */ +NO_SANITIZE("alignment") +size_t +lzf_compress (const void *const in_data, size_t in_len, + void *out_data, size_t 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 + size_t 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 ? (*hslot + LZF_HSLOT_BIAS) : NULL; /* avoid applying zero offset to null pointer */ + *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; + size_t 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; +} + |