2 * Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
4 * Redistribution and use in source and binary forms, with or without modifica-
5 * tion, are permitted provided that the following conditions are met:
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39 #define HSIZE (1 << (HLOG))
42 * don't play with this unless you benchmark!
43 * decompression is not dependent on the hash function
44 * the hashing function might seem strange, just believe me
48 # define FRST(p) (((p[0]) << 8) | p[1])
49 # define NEXT(v,p) (((v) << 8) | p[2])
51 # define IDX(h) ((( h >> (3*8 - HLOG)) - h ) & (HSIZE - 1))
53 # define IDX(h) ((( h >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
55 # define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
59 * IDX works because it is very similar to a multiplicative hash, e.g.
60 * ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1))
61 * the latter is also quite fast on newer CPUs, and compresses similarly.
63 * the next one is also quite good, albeit slow ;)
64 * (int)(cos(h & 0xffffff) * 1e6)
68 /* original lzv-like hash function, much worse and thus slower */
69 # define FRST(p) (p[0] << 5) ^ p[1]
70 # define NEXT(v,p) ((v) << 5) ^ p[2]
71 # define IDX(h) ((h) & (HSIZE - 1))
74 #define MAX_LIT (1 << 5)
75 #define MAX_OFF (1 << 13)
76 #define MAX_REF ((1 << 8) + (1 << 3))
79 # define expect(expr,value) __builtin_expect ((expr),(value))
80 # define inline inline
82 # define expect(expr,value) (expr)
83 # define inline static
86 #define expect_false(expr) expect ((expr) != 0, 0)
87 #define expect_true(expr) expect ((expr) != 0, 1)
92 * 000LLLLL <L+1> ; literal
93 * LLLooooo oooooooo ; backref L
94 * 111ooooo LLLLLLLL oooooooo ; backref L+7
99 lzf_compress (const void *const in_data, unsigned int in_len,
100 void *out_data, unsigned int out_len
110 const u8 *ip = (const u8 *)in_data;
111 u8 *op = (u8 *)out_data;
112 const u8 *in_end = ip + in_len;
113 u8 *out_end = op + out_len;
116 /* off requires a type wide enough to hold a general pointer difference.
117 * ISO C doesn't have that (size_t might not be enough and ptrdiff_t only
118 * works for differences within a single object). We also assume that no
119 * no bit pattern traps. Since the only platform that is both non-POSIX
120 * and fails to support both assumptions is windows 64 bit, we make a
121 * special workaround for it.
123 #if defined (WIN32) && defined (_M_X64)
124 unsigned _int64 off; /* workaround for missing POSIX compliance */
131 if (!in_len || !out_len)
135 memset (htab, 0, sizeof (htab));
137 for (hslot = htab; hslot < htab + HSIZE; hslot++)
142 lit = 0; op++; /* start run */
145 while (ip < in_end - 2)
147 hval = NEXT (hval, ip);
148 hslot = htab + IDX (hval);
149 ref = *hslot; *hslot = ip;
153 && ref < ip /* the next test will actually take care of this, but this is faster */
155 && (off = ip - ref - 1) < MAX_OFF
157 && ref > (const u8 *)in_data
163 && *(const u16 *)ref == *(const u16 *)ip
168 /* match found at *ref++ */
169 unsigned int len = 2;
170 unsigned int maxlen = in_end - ip - len;
171 maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
173 if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */
174 if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */
177 op [- lit - 1] = lit - 1; /* stop run */
178 op -= !lit; /* undo run if length is zero */
182 if (expect_true (maxlen > 16))
184 len++; if (ref [len] != ip [len]) break;
185 len++; if (ref [len] != ip [len]) break;
186 len++; if (ref [len] != ip [len]) break;
187 len++; if (ref [len] != ip [len]) break;
189 len++; if (ref [len] != ip [len]) break;
190 len++; if (ref [len] != ip [len]) break;
191 len++; if (ref [len] != ip [len]) break;
192 len++; if (ref [len] != ip [len]) break;
194 len++; if (ref [len] != ip [len]) break;
195 len++; if (ref [len] != ip [len]) break;
196 len++; if (ref [len] != ip [len]) break;
197 len++; if (ref [len] != ip [len]) break;
199 len++; if (ref [len] != ip [len]) break;
200 len++; if (ref [len] != ip [len]) break;
201 len++; if (ref [len] != ip [len]) break;
202 len++; if (ref [len] != ip [len]) break;
207 while (len < maxlen && ref[len] == ip[len]);
212 len -= 2; /* len is now #octets - 1 */
217 *op++ = (off >> 8) + (len << 5);
221 *op++ = (off >> 8) + ( 7 << 5);
226 lit = 0; op++; /* start run */
230 if (expect_false (ip >= in_end - 2))
233 #if ULTRA_FAST || VERY_FAST
235 # if VERY_FAST && !ULTRA_FAST
240 hval = NEXT (hval, ip);
241 htab[IDX (hval)] = ip;
244 # if VERY_FAST && !ULTRA_FAST
245 hval = NEXT (hval, ip);
246 htab[IDX (hval)] = ip;
254 hval = NEXT (hval, ip);
255 htab[IDX (hval)] = ip;
263 /* one more literal byte we must copy */
264 if (expect_false (op >= out_end))
267 lit++; *op++ = *ip++;
269 if (expect_false (lit == MAX_LIT))
271 op [- lit - 1] = lit - 1; /* stop run */
272 lit = 0; op++; /* start run */
277 if (op + 3 > out_end) /* at most 3 bytes can be missing here */
282 lit++; *op++ = *ip++;
284 if (expect_false (lit == MAX_LIT))
286 op [- lit - 1] = lit - 1; /* stop run */
287 lit = 0; op++; /* start run */
291 op [- lit - 1] = lit - 1; /* end run */
292 op -= !lit; /* undo run if length is zero */
294 return op - (u8 *)out_data;
298 # define SET_ERRNO(n)
301 # define SET_ERRNO(n) errno = (n)
304 #if (__i386 || __amd64) && __GNUC__ >= 3
305 # define lzf_movsb(dst, src, len) \
307 : "=D" (dst), "=S" (src), "=c" (len) \
308 : "0" (dst), "1" (src), "2" (len));
312 lzf_decompress (const void *const in_data, unsigned int in_len,
313 void *out_data, unsigned int out_len)
315 u8 const *ip = (const u8 *)in_data;
316 u8 *op = (u8 *)out_data;
317 u8 const *const in_end = ip + in_len;
318 u8 *const out_end = op + out_len;
322 unsigned int ctrl = *ip++;
324 if (ctrl < (1 << 5)) /* literal run */
328 if (op + ctrl > out_end)
335 if (ip + ctrl > in_end)
343 lzf_movsb (op, ip, ctrl);
350 else /* back reference */
352 unsigned int len = ctrl >> 5;
354 u8 *ref = op - ((ctrl & 0x1f) << 8) - 1;
377 if (op + len + 2 > out_end)
383 if (ref < (u8 *)out_data)
391 lzf_movsb (op, ref, len);
404 return op - (u8 *)out_data;