diff options
Diffstat (limited to 'src/liblzf/lzf_c.c')
| -rw-r--r-- | src/liblzf/lzf_c.c | 242 |
1 files changed, 242 insertions, 0 deletions
diff --git a/src/liblzf/lzf_c.c b/src/liblzf/lzf_c.c new file mode 100644 index 0000000..b9b9ef9 --- /dev/null +++ b/src/liblzf/lzf_c.c @@ -0,0 +1,242 @@ +/* + * Copyright (c) 2000-2005 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. + * + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * 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 version 2 (the "GPL"), 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]) +# define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1)) +#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 sligthly better + * + * 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)) + +/* + * compressed format + * + * 000LLLLL <L+1> ; 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; + + unsigned int hval = FRST (ip); + unsigned long off; + int lit = 0; + +#if INIT_HTAB +# if USE_MEMCPY + memset (htab, 0, sizeof (htab)); +# else + for (hslot = htab; hslot < htab + HSIZE; hslot++) + *hslot++ = ip; +# endif +#endif + + for (;;) + { + if (ip < in_end - 2) + { + hval = NEXT (hval, ip); + hslot = htab + IDX (hval); + ref = *hslot; *hslot = ip; + + if (1 +#if INIT_HTAB && !USE_MEMCPY + && 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 (op + lit + 1 + 3 >= out_end) + return 0; + + do + len++; + while (len < maxlen && ref[len] == ip[len]); + + if (lit) + { + *op++ = lit - 1; + lit = -lit; + do + *op++ = ip[lit]; + while (++lit); + } + + len -= 2; + ip++; + + if (len < 7) + { + *op++ = (off >> 8) + (len << 5); + } + else + { + *op++ = (off >> 8) + ( 7 << 5); + *op++ = len - 7; + } + + *op++ = off; + +#if ULTRA_FAST || VERY_FAST + ip += len; +#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 + do + { + hval = NEXT (hval, ip); + htab[IDX (hval)] = ip; + ip++; + } + while (len--); +#endif + continue; + } + } + else if (ip == in_end) + break; + + /* one more literal byte we must copy */ + lit++; + ip++; + + if (lit == MAX_LIT) + { + if (op + 1 + MAX_LIT >= out_end) + return 0; + + *op++ = MAX_LIT - 1; +#if USE_MEMCPY + memcpy (op, ip - MAX_LIT, MAX_LIT); + op += MAX_LIT; + lit = 0; +#else + lit = -lit; + do + *op++ = ip[lit]; + while (++lit); +#endif + } + } + + if (lit) + { + if (op + lit + 1 >= out_end) + return 0; + + *op++ = lit - 1; + lit = -lit; + do + *op++ = ip[lit]; + while (++lit); + } + + return op - (u8 *) out_data; +} |