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1 | /* | |
2 | * LibXDiff by Davide Libenzi ( File Differential Library ) | |
3 | * Copyright (C) 2003 Davide Libenzi | |
4 | * | |
5 | * This library is free software; you can redistribute it and/or | |
6 | * modify it under the terms of the GNU Lesser General Public | |
7 | * License as published by the Free Software Foundation; either | |
8 | * version 2.1 of the License, or (at your option) any later version. | |
9 | * | |
10 | * This library is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | * Lesser General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU Lesser General Public | |
16 | * License along with this library; if not, write to the Free Software | |
17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
18 | * | |
19 | * Davide Libenzi <davidel@xmailserver.org> | |
20 | * | |
21 | */ | |
22 | ||
23 | #include "xinclude.h" | |
24 | ||
25 | ||
26 | ||
27 | #define XDL_MAX_COST_MIN 256 | |
28 | #define XDL_HEUR_MIN_COST 256 | |
29 | #define XDL_LINE_MAX (long)((1UL << (8 * sizeof(long) - 1)) - 1) | |
30 | #define XDL_SNAKE_CNT 20 | |
31 | #define XDL_K_HEUR 4 | |
32 | ||
33 | ||
34 | ||
35 | typedef struct s_xdpsplit { | |
36 | long i1, i2; | |
37 | int min_lo, min_hi; | |
38 | } xdpsplit_t; | |
39 | ||
40 | ||
41 | ||
42 | ||
43 | static long xdl_split(unsigned long const *ha1, long off1, long lim1, | |
44 | unsigned long const *ha2, long off2, long lim2, | |
45 | long *kvdf, long *kvdb, int need_min, xdpsplit_t *spl, | |
46 | xdalgoenv_t *xenv); | |
47 | static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1, long chg2); | |
48 | ||
49 | ||
50 | ||
51 | ||
52 | /* | |
53 | * See "An O(ND) Difference Algorithm and its Variations", by Eugene Myers. | |
54 | * Basically considers a "box" (off1, off2, lim1, lim2) and scan from both | |
55 | * the forward diagonal starting from (off1, off2) and the backward diagonal | |
56 | * starting from (lim1, lim2). If the K values on the same diagonal crosses | |
57 | * returns the furthest point of reach. We might end up having to expensive | |
58 | * cases using this algorithm is full, so a little bit of heuristic is needed | |
59 | * to cut the search and to return a suboptimal point. | |
60 | */ | |
61 | static long xdl_split(unsigned long const *ha1, long off1, long lim1, | |
62 | unsigned long const *ha2, long off2, long lim2, | |
63 | long *kvdf, long *kvdb, int need_min, xdpsplit_t *spl, | |
64 | xdalgoenv_t *xenv) { | |
65 | long dmin = off1 - lim2, dmax = lim1 - off2; | |
66 | long fmid = off1 - off2, bmid = lim1 - lim2; | |
67 | long odd = (fmid - bmid) & 1; | |
68 | long fmin = fmid, fmax = fmid; | |
69 | long bmin = bmid, bmax = bmid; | |
70 | long ec, d, i1, i2, prev1, best, dd, v, k; | |
71 | ||
72 | /* | |
73 | * Set initial diagonal values for both forward and backward path. | |
74 | */ | |
75 | kvdf[fmid] = off1; | |
76 | kvdb[bmid] = lim1; | |
77 | ||
78 | for (ec = 1;; ec++) { | |
79 | int got_snake = 0; | |
80 | ||
81 | /* | |
82 | * We need to extent the diagonal "domain" by one. If the next | |
83 | * values exits the box boundaries we need to change it in the | |
84 | * opposite direction because (max - min) must be a power of two. | |
85 | * Also we initialize the extenal K value to -1 so that we can | |
86 | * avoid extra conditions check inside the core loop. | |
87 | */ | |
88 | if (fmin > dmin) | |
89 | kvdf[--fmin - 1] = -1; | |
90 | else | |
91 | ++fmin; | |
92 | if (fmax < dmax) | |
93 | kvdf[++fmax + 1] = -1; | |
94 | else | |
95 | --fmax; | |
96 | ||
97 | for (d = fmax; d >= fmin; d -= 2) { | |
98 | if (kvdf[d - 1] >= kvdf[d + 1]) | |
99 | i1 = kvdf[d - 1] + 1; | |
100 | else | |
101 | i1 = kvdf[d + 1]; | |
102 | prev1 = i1; | |
103 | i2 = i1 - d; | |
104 | for (; i1 < lim1 && i2 < lim2 && ha1[i1] == ha2[i2]; i1++, i2++); | |
105 | if (i1 - prev1 > xenv->snake_cnt) | |
106 | got_snake = 1; | |
107 | kvdf[d] = i1; | |
108 | if (odd && bmin <= d && d <= bmax && kvdb[d] <= i1) { | |
109 | spl->i1 = i1; | |
110 | spl->i2 = i2; | |
111 | spl->min_lo = spl->min_hi = 1; | |
112 | return ec; | |
113 | } | |
114 | } | |
115 | ||
116 | /* | |
117 | * We need to extent the diagonal "domain" by one. If the next | |
118 | * values exits the box boundaries we need to change it in the | |
119 | * opposite direction because (max - min) must be a power of two. | |
120 | * Also we initialize the extenal K value to -1 so that we can | |
121 | * avoid extra conditions check inside the core loop. | |
122 | */ | |
123 | if (bmin > dmin) | |
124 | kvdb[--bmin - 1] = XDL_LINE_MAX; | |
125 | else | |
126 | ++bmin; | |
127 | if (bmax < dmax) | |
128 | kvdb[++bmax + 1] = XDL_LINE_MAX; | |
129 | else | |
130 | --bmax; | |
131 | ||
132 | for (d = bmax; d >= bmin; d -= 2) { | |
133 | if (kvdb[d - 1] < kvdb[d + 1]) | |
134 | i1 = kvdb[d - 1]; | |
135 | else | |
136 | i1 = kvdb[d + 1] - 1; | |
137 | prev1 = i1; | |
138 | i2 = i1 - d; | |
139 | for (; i1 > off1 && i2 > off2 && ha1[i1 - 1] == ha2[i2 - 1]; i1--, i2--); | |
140 | if (prev1 - i1 > xenv->snake_cnt) | |
141 | got_snake = 1; | |
142 | kvdb[d] = i1; | |
143 | if (!odd && fmin <= d && d <= fmax && i1 <= kvdf[d]) { | |
144 | spl->i1 = i1; | |
145 | spl->i2 = i2; | |
146 | spl->min_lo = spl->min_hi = 1; | |
147 | return ec; | |
148 | } | |
149 | } | |
150 | ||
151 | if (need_min) | |
152 | continue; | |
153 | ||
154 | /* | |
155 | * If the edit cost is above the heuristic trigger and if | |
156 | * we got a good snake, we sample current diagonals to see | |
157 | * if some of the, have reached an "interesting" path. Our | |
158 | * measure is a function of the distance from the diagonal | |
159 | * corner (i1 + i2) penalized with the distance from the | |
160 | * mid diagonal itself. If this value is above the current | |
161 | * edit cost times a magic factor (XDL_K_HEUR) we consider | |
162 | * it interesting. | |
163 | */ | |
164 | if (got_snake && ec > xenv->heur_min) { | |
165 | for (best = 0, d = fmax; d >= fmin; d -= 2) { | |
166 | dd = d > fmid ? d - fmid: fmid - d; | |
167 | i1 = kvdf[d]; | |
168 | i2 = i1 - d; | |
169 | v = (i1 - off1) + (i2 - off2) - dd; | |
170 | ||
171 | if (v > XDL_K_HEUR * ec && v > best && | |
172 | off1 + xenv->snake_cnt <= i1 && i1 < lim1 && | |
173 | off2 + xenv->snake_cnt <= i2 && i2 < lim2) { | |
174 | for (k = 1; ha1[i1 - k] == ha2[i2 - k]; k++) | |
175 | if (k == xenv->snake_cnt) { | |
176 | best = v; | |
177 | spl->i1 = i1; | |
178 | spl->i2 = i2; | |
179 | break; | |
180 | } | |
181 | } | |
182 | } | |
183 | if (best > 0) { | |
184 | spl->min_lo = 1; | |
185 | spl->min_hi = 0; | |
186 | return ec; | |
187 | } | |
188 | ||
189 | for (best = 0, d = bmax; d >= bmin; d -= 2) { | |
190 | dd = d > bmid ? d - bmid: bmid - d; | |
191 | i1 = kvdb[d]; | |
192 | i2 = i1 - d; | |
193 | v = (lim1 - i1) + (lim2 - i2) - dd; | |
194 | ||
195 | if (v > XDL_K_HEUR * ec && v > best && | |
196 | off1 < i1 && i1 <= lim1 - xenv->snake_cnt && | |
197 | off2 < i2 && i2 <= lim2 - xenv->snake_cnt) { | |
198 | for (k = 0; ha1[i1 + k] == ha2[i2 + k]; k++) | |
199 | if (k == xenv->snake_cnt - 1) { | |
200 | best = v; | |
201 | spl->i1 = i1; | |
202 | spl->i2 = i2; | |
203 | break; | |
204 | } | |
205 | } | |
206 | } | |
207 | if (best > 0) { | |
208 | spl->min_lo = 0; | |
209 | spl->min_hi = 1; | |
210 | return ec; | |
211 | } | |
212 | } | |
213 | ||
214 | /* | |
215 | * Enough is enough. We spent too much time here and now we collect | |
216 | * the furthest reaching path using the (i1 + i2) measure. | |
217 | */ | |
218 | if (ec >= xenv->mxcost) { | |
219 | long fbest, fbest1, bbest, bbest1; | |
220 | ||
221 | fbest = -1; | |
222 | for (d = fmax; d >= fmin; d -= 2) { | |
223 | i1 = XDL_MIN(kvdf[d], lim1); | |
224 | i2 = i1 - d; | |
225 | if (lim2 < i2) | |
226 | i1 = lim2 + d, i2 = lim2; | |
227 | if (fbest < i1 + i2) { | |
228 | fbest = i1 + i2; | |
229 | fbest1 = i1; | |
230 | } | |
231 | } | |
232 | ||
233 | bbest = XDL_LINE_MAX; | |
234 | for (d = bmax; d >= bmin; d -= 2) { | |
235 | i1 = XDL_MAX(off1, kvdb[d]); | |
236 | i2 = i1 - d; | |
237 | if (i2 < off2) | |
238 | i1 = off2 + d, i2 = off2; | |
239 | if (i1 + i2 < bbest) { | |
240 | bbest = i1 + i2; | |
241 | bbest1 = i1; | |
242 | } | |
243 | } | |
244 | ||
245 | if ((lim1 + lim2) - bbest < fbest - (off1 + off2)) { | |
246 | spl->i1 = fbest1; | |
247 | spl->i2 = fbest - fbest1; | |
248 | spl->min_lo = 1; | |
249 | spl->min_hi = 0; | |
250 | } else { | |
251 | spl->i1 = bbest1; | |
252 | spl->i2 = bbest - bbest1; | |
253 | spl->min_lo = 0; | |
254 | spl->min_hi = 1; | |
255 | } | |
256 | return ec; | |
257 | } | |
258 | } | |
259 | ||
260 | return -1; | |
261 | } | |
262 | ||
263 | ||
264 | /* | |
265 | * Rule: "Divide et Impera". Recursively split the box in sub-boxes by calling | |
266 | * the box splitting function. Note that the real job (marking changed lines) | |
267 | * is done in the two boundary reaching checks. | |
268 | */ | |
269 | int xdl_recs_cmp(diffdata_t *dd1, long off1, long lim1, | |
270 | diffdata_t *dd2, long off2, long lim2, | |
271 | long *kvdf, long *kvdb, int need_min, xdalgoenv_t *xenv) { | |
272 | unsigned long const *ha1 = dd1->ha, *ha2 = dd2->ha; | |
273 | ||
274 | /* | |
275 | * Shrink the box by walking through each diagonal snake (SW and NE). | |
276 | */ | |
277 | for (; off1 < lim1 && off2 < lim2 && ha1[off1] == ha2[off2]; off1++, off2++); | |
278 | for (; off1 < lim1 && off2 < lim2 && ha1[lim1 - 1] == ha2[lim2 - 1]; lim1--, lim2--); | |
279 | ||
280 | /* | |
281 | * If one dimension is empty, then all records on the other one must | |
282 | * be obviously changed. | |
283 | */ | |
284 | if (off1 == lim1) { | |
285 | char *rchg2 = dd2->rchg; | |
286 | long *rindex2 = dd2->rindex; | |
287 | ||
288 | for (; off2 < lim2; off2++) | |
289 | rchg2[rindex2[off2]] = 1; | |
290 | } else if (off2 == lim2) { | |
291 | char *rchg1 = dd1->rchg; | |
292 | long *rindex1 = dd1->rindex; | |
293 | ||
294 | for (; off1 < lim1; off1++) | |
295 | rchg1[rindex1[off1]] = 1; | |
296 | } else { | |
297 | long ec; | |
298 | xdpsplit_t spl; | |
299 | ||
300 | /* | |
301 | * Divide ... | |
302 | */ | |
303 | if ((ec = xdl_split(ha1, off1, lim1, ha2, off2, lim2, kvdf, kvdb, | |
304 | need_min, &spl, xenv)) < 0) { | |
305 | ||
306 | return -1; | |
307 | } | |
308 | ||
309 | /* | |
310 | * ... et Impera. | |
311 | */ | |
312 | if (xdl_recs_cmp(dd1, off1, spl.i1, dd2, off2, spl.i2, | |
313 | kvdf, kvdb, spl.min_lo, xenv) < 0 || | |
314 | xdl_recs_cmp(dd1, spl.i1, lim1, dd2, spl.i2, lim2, | |
315 | kvdf, kvdb, spl.min_hi, xenv) < 0) { | |
316 | ||
317 | return -1; | |
318 | } | |
319 | } | |
320 | ||
321 | return 0; | |
322 | } | |
323 | ||
324 | ||
325 | int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp, | |
326 | xdfenv_t *xe) { | |
327 | long ndiags; | |
328 | long *kvd, *kvdf, *kvdb; | |
329 | xdalgoenv_t xenv; | |
330 | diffdata_t dd1, dd2; | |
331 | ||
332 | if (xdl_prepare_env(mf1, mf2, xpp, xe) < 0) { | |
333 | ||
334 | return -1; | |
335 | } | |
336 | ||
337 | /* | |
338 | * Allocate and setup K vectors to be used by the differential algorithm. | |
339 | * One is to store the forward path and one to store the backward path. | |
340 | */ | |
341 | ndiags = xe->xdf1.nreff + xe->xdf2.nreff + 3; | |
342 | if (!(kvd = (long *) xdl_malloc((2 * ndiags + 2) * sizeof(long)))) { | |
343 | ||
344 | xdl_free_env(xe); | |
345 | return -1; | |
346 | } | |
347 | kvdf = kvd; | |
348 | kvdb = kvdf + ndiags; | |
349 | kvdf += xe->xdf2.nreff + 1; | |
350 | kvdb += xe->xdf2.nreff + 1; | |
351 | ||
352 | /* | |
353 | * Classical integer square root approximation using shifts. | |
354 | */ | |
355 | xenv.mxcost = 1; | |
356 | for (; ndiags; ndiags >>= 2) | |
357 | xenv.mxcost <<= 1; | |
358 | if (xenv.mxcost < XDL_MAX_COST_MIN) | |
359 | xenv.mxcost = XDL_MAX_COST_MIN; | |
360 | xenv.snake_cnt = XDL_SNAKE_CNT; | |
361 | xenv.heur_min = XDL_HEUR_MIN_COST; | |
362 | ||
363 | dd1.nrec = xe->xdf1.nreff; | |
364 | dd1.ha = xe->xdf1.ha; | |
365 | dd1.rchg = xe->xdf1.rchg; | |
366 | dd1.rindex = xe->xdf1.rindex; | |
367 | dd2.nrec = xe->xdf2.nreff; | |
368 | dd2.ha = xe->xdf2.ha; | |
369 | dd2.rchg = xe->xdf2.rchg; | |
370 | dd2.rindex = xe->xdf2.rindex; | |
371 | ||
372 | if (xdl_recs_cmp(&dd1, 0, dd1.nrec, &dd2, 0, dd2.nrec, | |
373 | kvdf, kvdb, (xpp->flags & XDF_NEED_MINIMAL) != 0, &xenv) < 0) { | |
374 | ||
375 | xdl_free(kvd); | |
376 | xdl_free_env(xe); | |
377 | return -1; | |
378 | } | |
379 | ||
380 | xdl_free(kvd); | |
381 | ||
382 | return 0; | |
383 | } | |
384 | ||
385 | ||
386 | static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1, long chg2) { | |
387 | xdchange_t *xch; | |
388 | ||
389 | if (!(xch = (xdchange_t *) xdl_malloc(sizeof(xdchange_t)))) | |
390 | return NULL; | |
391 | ||
392 | xch->next = xscr; | |
393 | xch->i1 = i1; | |
394 | xch->i2 = i2; | |
395 | xch->chg1 = chg1; | |
396 | xch->chg2 = chg2; | |
397 | ||
398 | return xch; | |
399 | } | |
400 | ||
401 | ||
402 | int xdl_build_script(xdfenv_t *xe, xdchange_t **xscr) { | |
403 | xdchange_t *cscr = NULL, *xch; | |
404 | char *rchg1 = xe->xdf1.rchg, *rchg2 = xe->xdf2.rchg; | |
405 | long i1, i2, l1, l2; | |
406 | ||
407 | /* | |
408 | * Trivial. Collects "groups" of changes and creates an edit script. | |
409 | */ | |
410 | for (i1 = xe->xdf1.nrec, i2 = xe->xdf2.nrec; i1 >= 0 || i2 >= 0; i1--, i2--) | |
411 | if (rchg1[i1 - 1] || rchg2[i2 - 1]) { | |
412 | for (l1 = i1; rchg1[i1 - 1]; i1--); | |
413 | for (l2 = i2; rchg2[i2 - 1]; i2--); | |
414 | ||
415 | if (!(xch = xdl_add_change(cscr, i1, i2, l1 - i1, l2 - i2))) { | |
416 | xdl_free_script(cscr); | |
417 | return -1; | |
418 | } | |
419 | cscr = xch; | |
420 | } | |
421 | ||
422 | *xscr = cscr; | |
423 | ||
424 | return 0; | |
425 | } | |
426 | ||
427 | ||
428 | void xdl_free_script(xdchange_t *xscr) { | |
429 | xdchange_t *xch; | |
430 | ||
431 | while ((xch = xscr) != NULL) { | |
432 | xscr = xscr->next; | |
433 | xdl_free(xch); | |
434 | } | |
435 | } | |
436 | ||
437 | ||
438 | int xdl_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp, | |
439 | xdemitconf_t const *xecfg, xdemitcb_t *ecb) { | |
440 | xdchange_t *xscr; | |
441 | xdfenv_t xe; | |
442 | ||
443 | if (xdl_do_diff(mf1, mf2, xpp, &xe) < 0) { | |
444 | ||
445 | return -1; | |
446 | } | |
447 | ||
448 | if (xdl_build_script(&xe, &xscr) < 0) { | |
449 | ||
450 | xdl_free_env(&xe); | |
451 | return -1; | |
452 | } | |
453 | ||
454 | if (xscr) { | |
455 | if (xdl_emit_diff(&xe, xscr, ecb, xecfg) < 0) { | |
456 | ||
457 | xdl_free_script(xscr); | |
458 | xdl_free_env(&xe); | |
459 | return -1; | |
460 | } | |
461 | ||
462 | xdl_free_script(xscr); | |
463 | } | |
464 | ||
465 | xdl_free_env(&xe); | |
466 | ||
467 | return 0; | |
468 | } | |
469 |