| 1 | /*
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| 2 | * Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
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| 3 | *
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| 4 | * Redistribution and use in source and binary forms, with or without modifica-
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| 5 | * tion, are permitted provided that the following conditions are met:
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| 6 | *
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| 7 | * 1. Redistributions of source code must retain the above copyright notice,
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| 8 | * this list of conditions and the following disclaimer.
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| 9 | *
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| 10 | * 2. Redistributions in binary form must reproduce the above copyright
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| 11 | * notice, this list of conditions and the following disclaimer in the
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| 12 | * documentation and/or other materials provided with the distribution.
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| 13 | *
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| 14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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| 15 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
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| 16 | * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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| 17 | * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
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| 18 | * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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| 19 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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| 20 | * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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| 21 | * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
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| 22 | * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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| 23 | * OF THE POSSIBILITY OF SUCH DAMAGE.
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| 24 | *
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| 25 | * Alternatively, the contents of this file may be used under the terms of
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| 26 | * the GNU General Public License ("GPL") version 2 or any later version,
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| 27 | * in which case the provisions of the GPL are applicable instead of
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| 28 | * the above. If you wish to allow the use of your version of this file
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| 29 | * only under the terms of the GPL and not to allow others to use your
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| 30 | * version of this file under the BSD license, indicate your decision
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| 31 | * by deleting the provisions above and replace them with the notice
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| 32 | * and other provisions required by the GPL. If you do not delete the
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| 33 | * provisions above, a recipient may use your version of this file under
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| 34 | * either the BSD or the GPL.
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| 35 | */
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| 36 |
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| 37 | #include "lzfP.h"
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| 38 | #ifdef VBOX
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| 39 | # include "lzf.h" /* need the prototype */
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| 40 | #endif
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| 41 |
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| 42 | #define HSIZE (1 << (HLOG))
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| 43 |
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| 44 | /*
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| 45 | * don't play with this unless you benchmark!
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| 46 | * decompression is not dependent on the hash function
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| 47 | * the hashing function might seem strange, just believe me
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| 48 | * it works ;)
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| 49 | */
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| 50 | #ifndef FRST
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| 51 | # define FRST(p) (((p[0]) << 8) | p[1])
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| 52 | # define NEXT(v,p) (((v) << 8) | p[2])
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| 53 | # if ULTRA_FAST
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| 54 | # define IDX(h) ((( h >> (3*8 - HLOG)) - h ) & (HSIZE - 1))
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| 55 | # elif VERY_FAST
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| 56 | # define IDX(h) ((( h >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
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| 57 | # else
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| 58 | # define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
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| 59 | # endif
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| 60 | #endif
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| 61 | /*
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| 62 | * IDX works because it is very similar to a multiplicative hash, e.g.
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| 63 | * ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1))
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| 64 | * the latter is also quite fast on newer CPUs, and compresses similarly.
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| 65 | *
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| 66 | * the next one is also quite good, albeit slow ;)
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| 67 | * (int)(cos(h & 0xffffff) * 1e6)
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| 68 | */
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| 69 |
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| 70 | #if 0
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| 71 | /* original lzv-like hash function, much worse and thus slower */
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| 72 | # define FRST(p) (p[0] << 5) ^ p[1]
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| 73 | # define NEXT(v,p) ((v) << 5) ^ p[2]
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| 74 | # define IDX(h) ((h) & (HSIZE - 1))
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| 75 | #endif
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| 76 |
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| 77 | #define MAX_LIT (1 << 5)
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| 78 | #define MAX_OFF (1 << 13)
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| 79 | #define MAX_REF ((1 << 8) + (1 << 3))
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| 80 |
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| 81 | #if __GNUC__ >= 3
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| 82 | # define expect(expr,value) __builtin_expect ((expr),(value))
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| 83 | # define inline inline
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| 84 | #else
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| 85 | # define expect(expr,value) (expr)
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| 86 | # define inline static
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| 87 | #endif
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| 88 |
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| 89 | #define expect_false(expr) expect ((expr) != 0, 0)
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| 90 | #define expect_true(expr) expect ((expr) != 0, 1)
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| 91 |
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| 92 | /*
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| 93 | * compressed format
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| 94 | *
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| 95 | * 000LLLLL <L+1> ; literal
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| 96 | * LLLooooo oooooooo ; backref L
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| 97 | * 111ooooo LLLLLLLL oooooooo ; backref L+7
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| 98 | *
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| 99 | */
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| 100 |
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| 101 | unsigned int
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| 102 | lzf_compress (const void *const in_data, unsigned int in_len,
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| 103 | void *out_data, unsigned int out_len
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| 104 | #if LZF_STATE_ARG
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| 105 | , LZF_STATE htab
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| 106 | #endif
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| 107 | )
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| 108 | {
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| 109 | #if !LZF_STATE_ARG
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| 110 | LZF_STATE htab;
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| 111 | #endif
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| 112 | const u8 **hslot;
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| 113 | const u8 *ip = (const u8 *)in_data;
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| 114 | u8 *op = (u8 *)out_data;
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| 115 | const u8 *in_end = ip + in_len;
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| 116 | u8 *out_end = op + out_len;
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| 117 | const u8 *ref;
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| 118 |
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| 119 | /* off requires a type wide enough to hold a general pointer difference.
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| 120 | * ISO C doesn't have that (size_t might not be enough and ptrdiff_t only
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| 121 | * works for differences within a single object). We also assume that no
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| 122 | * no bit pattern traps. Since the only platform that is both non-POSIX
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| 123 | * and fails to support both assumptions is windows 64 bit, we make a
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| 124 | * special workaround for it.
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| 125 | */
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| 126 | #if defined (WIN32) && defined (_M_X64)
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| 127 | unsigned _int64 off; /* workaround for missing POSIX compliance */
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| 128 | #else
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| 129 | unsigned long off;
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| 130 | #endif
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| 131 | unsigned int hval;
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| 132 | int lit;
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| 133 |
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| 134 | if (!in_len || !out_len)
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| 135 | return 0;
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| 136 |
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| 137 | #if INIT_HTAB
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| 138 | memset (htab, 0, sizeof (htab));
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| 139 | # if 0
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| 140 | for (hslot = htab; hslot < htab + HSIZE; hslot++)
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| 141 | *hslot++ = ip;
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| 142 | # endif
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| 143 | #endif
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| 144 |
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| 145 | lit = 0; op++; /* start run */
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| 146 |
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| 147 | hval = FRST (ip);
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| 148 | while (ip < in_end - 2)
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| 149 | {
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| 150 | hval = NEXT (hval, ip);
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| 151 | hslot = htab + IDX (hval);
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| 152 | ref = *hslot; *hslot = ip;
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| 153 |
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| 154 | if (1
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| 155 | #if INIT_HTAB
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| 156 | && ref < ip /* the next test will actually take care of this, but this is faster */
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| 157 | #endif
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| 158 | && (off = ip - ref - 1) < MAX_OFF
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| 159 | && ip + 4 < in_end
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| 160 | && ref > (u8 *)in_data
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| 161 | #if STRICT_ALIGN
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| 162 | && ref[0] == ip[0]
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| 163 | && ref[1] == ip[1]
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| 164 | && ref[2] == ip[2]
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| 165 | #else
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| 166 | && *(u16 *)ref == *(u16 *)ip
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| 167 | && ref[2] == ip[2]
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| 168 | #endif
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| 169 | )
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| 170 | {
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| 171 | /* match found at *ref++ */
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| 172 | unsigned int len = 2;
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| 173 | unsigned int maxlen = in_end - ip - len;
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| 174 | maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
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| 175 |
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| 176 | op [- lit - 1] = lit - 1; /* stop run */
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| 177 | op -= !lit; /* undo run if length is zero */
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| 178 |
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| 179 | if (expect_false (op + 3 + 1 >= out_end))
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| 180 | return 0;
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| 181 |
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| 182 | for (;;)
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| 183 | {
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| 184 | if (expect_true (maxlen > 16))
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| 185 | {
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| 186 | len++; if (ref [len] != ip [len]) break;
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| 187 | len++; if (ref [len] != ip [len]) break;
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| 188 | len++; if (ref [len] != ip [len]) break;
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| 189 | len++; if (ref [len] != ip [len]) break;
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| 190 |
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| 191 | len++; if (ref [len] != ip [len]) break;
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| 192 | len++; if (ref [len] != ip [len]) break;
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| 193 | len++; if (ref [len] != ip [len]) break;
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| 194 | len++; if (ref [len] != ip [len]) break;
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| 195 |
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| 196 | len++; if (ref [len] != ip [len]) break;
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| 197 | len++; if (ref [len] != ip [len]) break;
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| 198 | len++; if (ref [len] != ip [len]) break;
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| 199 | len++; if (ref [len] != ip [len]) break;
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| 200 |
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| 201 | len++; if (ref [len] != ip [len]) break;
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| 202 | len++; if (ref [len] != ip [len]) break;
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| 203 | len++; if (ref [len] != ip [len]) break;
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| 204 | len++; if (ref [len] != ip [len]) break;
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| 205 | }
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| 206 |
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| 207 | do
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| 208 | len++;
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| 209 | while (len < maxlen && ref[len] == ip[len]);
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| 210 |
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| 211 | break;
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| 212 | }
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| 213 |
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| 214 | len -= 2; /* len is now #octets - 1 */
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| 215 | ip++;
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| 216 |
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| 217 | if (len < 7)
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| 218 | {
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| 219 | *op++ = (off >> 8) + (len << 5);
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| 220 | }
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| 221 | else
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| 222 | {
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| 223 | *op++ = (off >> 8) + ( 7 << 5);
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| 224 | *op++ = len - 7;
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| 225 | }
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| 226 |
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| 227 | *op++ = off;
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| 228 | lit = 0; op++; /* start run */
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| 229 |
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| 230 | ip += len + 1;
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| 231 |
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| 232 | if (expect_false (ip >= in_end - 2))
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| 233 | break;
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| 234 |
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| 235 | #if ULTRA_FAST || VERY_FAST
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| 236 | --ip;
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| 237 | # if VERY_FAST && !ULTRA_FAST
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| 238 | --ip;
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| 239 | # endif
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| 240 | hval = FRST (ip);
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| 241 |
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| 242 | hval = NEXT (hval, ip);
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| 243 | htab[IDX (hval)] = ip;
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| 244 | ip++;
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| 245 |
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| 246 | # if VERY_FAST && !ULTRA_FAST
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| 247 | hval = NEXT (hval, ip);
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| 248 | htab[IDX (hval)] = ip;
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| 249 | ip++;
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| 250 | # endif
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| 251 | #else
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| 252 | ip -= len + 1;
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| 253 |
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| 254 | do
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| 255 | {
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| 256 | hval = NEXT (hval, ip);
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| 257 | htab[IDX (hval)] = ip;
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| 258 | ip++;
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| 259 | }
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| 260 | while (len--);
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| 261 | #endif
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| 262 | }
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| 263 | else
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| 264 | {
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| 265 | /* one more literal byte we must copy */
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| 266 | if (expect_false (op >= out_end))
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| 267 | return 0;
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| 268 |
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| 269 | lit++; *op++ = *ip++;
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| 270 |
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| 271 | if (expect_false (lit == MAX_LIT))
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| 272 | {
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| 273 | op [- lit - 1] = lit - 1; /* stop run */
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| 274 | lit = 0; op++; /* start run */
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| 275 | }
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| 276 | }
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| 277 | }
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| 278 |
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| 279 | if (op + 3 > out_end) /* at most 3 bytes can be missing here */
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| 280 | return 0;
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| 281 |
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| 282 | while (ip < in_end)
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| 283 | {
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| 284 | lit++; *op++ = *ip++;
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| 285 |
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| 286 | if (expect_false (lit == MAX_LIT))
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| 287 | {
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| 288 | op [- lit - 1] = lit - 1; /* stop run */
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| 289 | lit = 0; op++; /* start run */
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| 290 | }
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| 291 | }
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| 292 |
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| 293 | op [- lit - 1] = lit - 1; /* end run */
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| 294 | op -= !lit; /* undo run if length is zero */
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| 295 |
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| 296 | return op - (u8 *)out_data;
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| 297 | }
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| 298 |
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