[thirdparty/git.git] / xdiff / xprepare.c

/*
 *  LibXDiff by Davide Libenzi ( File Differential Library )
 *  Copyright (C) 2003  Davide Libenzi
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  Davide Libenzi <davidel@xmailserver.org>
 *
 */

#include "xinclude.h"


#define XDL_KPDIS_RUN 4


typedef struct s_xdlclass {
	struct s_xdlclass *next;
	unsigned long ha;
	char const *line;
	long size;
	long idx;
} xdlclass_t;

typedef struct s_xdlclassifier {
	unsigned int hbits;
	long hsize;
	xdlclass_t **rchash;
	chastore_t ncha;
	long count;
} xdlclassifier_t;


static int xdl_init_classifier(xdlclassifier_t *cf, long size);
static void xdl_free_classifier(xdlclassifier_t *cf);
static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
			       xrecord_t *rec);
static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
			   xdlclassifier_t *cf, xdfile_t *xdf);
static void xdl_free_ctx(xdfile_t *xdf);
static int xdl_clean_mmatch(char const *dis, long i, long s, long e);
static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2);
static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2);
static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2);


static int xdl_init_classifier(xdlclassifier_t *cf, long size) {
	long i;

	cf->hbits = xdl_hashbits((unsigned int) size);
	cf->hsize = 1 << cf->hbits;

	if (xdl_cha_init(&cf->ncha, sizeof(xdlclass_t), size / 4 + 1) < 0) {

		return -1;
	}
	if (!(cf->rchash = (xdlclass_t **) xdl_malloc(cf->hsize * sizeof(xdlclass_t *)))) {

		xdl_cha_free(&cf->ncha);
		return -1;
	}
	for (i = 0; i < cf->hsize; i++)
		cf->rchash[i] = NULL;

	cf->count = 0;

	return 0;
}


static void xdl_free_classifier(xdlclassifier_t *cf) {

	xdl_free(cf->rchash);
	xdl_cha_free(&cf->ncha);
}


static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
			       xrecord_t *rec) {
	long hi;
	char const *line;
	xdlclass_t *rcrec;

	line = rec->ptr;
	hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
	for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)
		if (rcrec->ha == rec->ha && rcrec->size == rec->size &&
		    !memcmp(line, rcrec->line, rec->size))
			break;

	if (!rcrec) {
		if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {

			return -1;
		}
		rcrec->idx = cf->count++;
		rcrec->line = line;
		rcrec->size = rec->size;
		rcrec->ha = rec->ha;
		rcrec->next = cf->rchash[hi];
		cf->rchash[hi] = rcrec;
	}

	rec->ha = (unsigned long) rcrec->idx;

	hi = (long) XDL_HASHLONG(rec->ha, hbits);
	rec->next = rhash[hi];
	rhash[hi] = rec;

	return 0;
}


static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
			   xdlclassifier_t *cf, xdfile_t *xdf) {
	unsigned int hbits;
	long i, nrec, hsize, bsize;
	unsigned long hav;
	char const *blk, *cur, *top, *prev;
	xrecord_t *crec;
	xrecord_t **recs, **rrecs;
	xrecord_t **rhash;
	unsigned long *ha;
	char *rchg;
	long *rindex;

	if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0) {

		return -1;
	}
	if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *)))) {

		xdl_cha_free(&xdf->rcha);
		return -1;
	}

	hbits = xdl_hashbits((unsigned int) narec);
	hsize = 1 << hbits;
	if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *)))) {

		xdl_free(recs);
		xdl_cha_free(&xdf->rcha);
		return -1;
	}
	for (i = 0; i < hsize; i++)
		rhash[i] = NULL;

	nrec = 0;
	if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
		for (top = blk + bsize;;) {
			if (cur >= top) {
				if (!(cur = blk = xdl_mmfile_next(mf, &bsize)))
					break;
				top = blk + bsize;
			}
			prev = cur;
			hav = xdl_hash_record(&cur, top);
			if (nrec >= narec) {
				narec *= 2;
				if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *)))) {

					xdl_free(rhash);
					xdl_free(recs);
					xdl_cha_free(&xdf->rcha);
					return -1;
				}
				recs = rrecs;
			}
			if (!(crec = xdl_cha_alloc(&xdf->rcha))) {

				xdl_free(rhash);
				xdl_free(recs);
				xdl_cha_free(&xdf->rcha);
				return -1;
			}
			crec->ptr = prev;
			crec->size = (long) (cur - prev);
			crec->ha = hav;
			recs[nrec++] = crec;

			if (xdl_classify_record(cf, rhash, hbits, crec) < 0) {

				xdl_free(rhash);
				xdl_free(recs);
				xdl_cha_free(&xdf->rcha);
				return -1;
			}
		}
	}

	if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char)))) {

		xdl_free(rhash);
		xdl_free(recs);
		xdl_cha_free(&xdf->rcha);
		return -1;
	}
	memset(rchg, 0, (nrec + 2) * sizeof(char));

	if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long)))) {

		xdl_free(rchg);
		xdl_free(rhash);
		xdl_free(recs);
		xdl_cha_free(&xdf->rcha);
		return -1;
	}
	if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long)))) {

		xdl_free(rindex);
		xdl_free(rchg);
		xdl_free(rhash);
		xdl_free(recs);
		xdl_cha_free(&xdf->rcha);
		return -1;
	}

	xdf->nrec = nrec;
	xdf->recs = recs;
	xdf->hbits = hbits;
	xdf->rhash = rhash;
	xdf->rchg = rchg + 1;
	xdf->rindex = rindex;
	xdf->nreff = 0;
	xdf->ha = ha;
	xdf->dstart = 0;
	xdf->dend = nrec - 1;

	return 0;
}


static void xdl_free_ctx(xdfile_t *xdf) {

	xdl_free(xdf->rhash);
	xdl_free(xdf->rindex);
	xdl_free(xdf->rchg - 1);
	xdl_free(xdf->ha);
	xdl_free(xdf->recs);
	xdl_cha_free(&xdf->rcha);
}


int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
		    xdfenv_t *xe) {
	long enl1, enl2;
	xdlclassifier_t cf;

	enl1 = xdl_guess_lines(mf1) + 1;
	enl2 = xdl_guess_lines(mf2) + 1;

	if (xdl_init_classifier(&cf, enl1 + enl2 + 1) < 0) {

		return -1;
	}

	if (xdl_prepare_ctx(mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {

		xdl_free_classifier(&cf);
		return -1;
	}
	if (xdl_prepare_ctx(mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {

		xdl_free_ctx(&xe->xdf1);
		xdl_free_classifier(&cf);
		return -1;
	}

	xdl_free_classifier(&cf);

	if (xdl_optimize_ctxs(&xe->xdf1, &xe->xdf2) < 0) {

		xdl_free_ctx(&xe->xdf2);
		xdl_free_ctx(&xe->xdf1);
		return -1;
	}

	return 0;
}


void xdl_free_env(xdfenv_t *xe) {

	xdl_free_ctx(&xe->xdf2);
	xdl_free_ctx(&xe->xdf1);
}


static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
	long r, rdis, rpdis;

	for (r = 1, rdis = 0, rpdis = 1; (i - r) >= s; r++) {
		if (!dis[i - r])
			rdis++;
		else if (dis[i - r] == 2)
			rpdis++;
		else
			break;
	}
	for (r = 1; (i + r) <= e; r++) {
		if (!dis[i + r])
			rdis++;
		else if (dis[i + r] == 2)
			rpdis++;
		else
			break;
	}

	return rpdis * XDL_KPDIS_RUN < (rpdis + rdis);
}


/*
 * Try to reduce the problem complexity, discard records that have no
 * matches on the other file. Also, lines that have multiple matches
 * might be potentially discarded if they happear in a run of discardable.
 */
static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2) {
	long i, rhi, nreff;
	unsigned long hav;
	xrecord_t **recs;
	xrecord_t *rec;
	char *dis, *dis1, *dis2;

	if (!(dis = (char *) xdl_malloc((xdf1->nrec + xdf2->nrec + 2) * sizeof(char)))) {

		return -1;
	}
	memset(dis, 0, (xdf1->nrec + xdf2->nrec + 2) * sizeof(char));
	dis1 = dis;
	dis2 = dis1 + xdf1->nrec + 1;

	for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
		hav = (*recs)->ha;
		rhi = (long) XDL_HASHLONG(hav, xdf2->hbits);
		for (rec = xdf2->rhash[rhi]; rec; rec = rec->next)
			if (rec->ha == hav && ++dis1[i] == 2)
				break;
	}

	for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
		hav = (*recs)->ha;
		rhi = (long) XDL_HASHLONG(hav, xdf1->hbits);
		for (rec = xdf1->rhash[rhi]; rec; rec = rec->next)
			if (rec->ha == hav && ++dis2[i] == 2)
				break;
	}

	for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
	     i <= xdf1->dend; i++, recs++) {
		if (dis1[i] == 1 ||
		    (dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
			xdf1->rindex[nreff] = i;
			xdf1->ha[nreff] = (*recs)->ha;
			nreff++;
		} else
			xdf1->rchg[i] = 1;
	}
	xdf1->nreff = nreff;

	for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
	     i <= xdf2->dend; i++, recs++) {
		if (dis2[i] == 1 ||
		    (dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
			xdf2->rindex[nreff] = i;
			xdf2->ha[nreff] = (*recs)->ha;
			nreff++;
		} else
			xdf2->rchg[i] = 1;
	}
	xdf2->nreff = nreff;

	xdl_free(dis);

	return 0;
}


/*
 * Early trim initial and terminal matching records.
 */
static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2) {
	long i, lim;
	xrecord_t **recs1, **recs2;

	recs1 = xdf1->recs;
	recs2 = xdf2->recs;
	for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
	     i++, recs1++, recs2++)
		if ((*recs1)->ha != (*recs2)->ha)
			break;

	xdf1->dstart = xdf2->dstart = i;

	recs1 = xdf1->recs + xdf1->nrec - 1;
	recs2 = xdf2->recs + xdf2->nrec - 1;
	for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
		if ((*recs1)->ha != (*recs2)->ha)
			break;

	xdf1->dend = xdf1->nrec - i - 1;
	xdf2->dend = xdf2->nrec - i - 1;

	return 0;
}


static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2) {

	if (xdl_trim_ends(xdf1, xdf2) < 0 ||
	    xdl_cleanup_records(xdf1, xdf2) < 0) {

		return -1;
	}

	return 0;
}
Commit	Line	Data
3443546f LT	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_KPDIS_RUN 4
	28
	29
	30
	31	typedef struct s_xdlclass {
	32	struct s_xdlclass *next;
	33	unsigned long ha;
	34	char const *line;
	35	long size;
	36	long idx;
	37	} xdlclass_t;
	38
	39	typedef struct s_xdlclassifier {
	40	unsigned int hbits;
	41	long hsize;
	42	xdlclass_t **rchash;
	43	chastore_t ncha;
	44	long count;
	45	} xdlclassifier_t;
	46
	47
	48
	49
	50	static int xdl_init_classifier(xdlclassifier_t *cf, long size);
	51	static void xdl_free_classifier(xdlclassifier_t *cf);
	52	static int xdl_classify_record(xdlclassifier_t cf, xrecord_t *rhash, unsigned int hbits,
	53	xrecord_t *rec);
	54	static int xdl_prepare_ctx(mmfile_t mf, long narec, xpparam_t const xpp,
	55	xdlclassifier_t cf, xdfile_t xdf);
	56	static void xdl_free_ctx(xdfile_t *xdf);
	57	static int xdl_clean_mmatch(char const *dis, long i, long s, long e);
	58	static int xdl_cleanup_records(xdfile_t xdf1, xdfile_t xdf2);
	59	static int xdl_trim_ends(xdfile_t xdf1, xdfile_t xdf2);
	60	static int xdl_optimize_ctxs(xdfile_t xdf1, xdfile_t xdf2);
	61
	62
	63
	64
65	static int xdl_init_classifier(xdlclassifier_t *cf, long size) {
66	long i;
67
68	cf->hbits = xdl_hashbits((unsigned int) size);
69	cf->hsize = 1 << cf->hbits;
70
71	if (xdl_cha_init(&cf->ncha, sizeof(xdlclass_t), size / 4 + 1) < 0) {
72
73	return -1;
74	}
75	if (!(cf->rchash = (xdlclass_t *) xdl_malloc(cf->hsize sizeof(xdlclass_t *)))) {
76
77	xdl_cha_free(&cf->ncha);
78	return -1;
79	}
80	for (i = 0; i < cf->hsize; i++)
81	cf->rchash[i] = NULL;
82
83	cf->count = 0;
84
85	return 0;
86	}
87
88
89	static void xdl_free_classifier(xdlclassifier_t *cf) {
90
91	xdl_free(cf->rchash);
92	xdl_cha_free(&cf->ncha);
93	}
94
95
96	static int xdl_classify_record(xdlclassifier_t cf, xrecord_t *rhash, unsigned int hbits,
97	xrecord_t *rec) {
98	long hi;
99	char const *line;
100	xdlclass_t *rcrec;
101
102	line = rec->ptr;
103	hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
104	for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)
105	if (rcrec->ha == rec->ha && rcrec->size == rec->size &&
106	!memcmp(line, rcrec->line, rec->size))
107	break;
108
109	if (!rcrec) {
110	if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {
111
112	return -1;
113	}
114	rcrec->idx = cf->count++;
115	rcrec->line = line;
116	rcrec->size = rec->size;
117	rcrec->ha = rec->ha;
118	rcrec->next = cf->rchash[hi];
119	cf->rchash[hi] = rcrec;
120	}
121
122	rec->ha = (unsigned long) rcrec->idx;
123
124	hi = (long) XDL_HASHLONG(rec->ha, hbits);
125	rec->next = rhash[hi];
126	rhash[hi] = rec;
127
128	return 0;
129	}
130
131
132	static int xdl_prepare_ctx(mmfile_t mf, long narec, xpparam_t const xpp,
133	xdlclassifier_t cf, xdfile_t xdf) {
134	unsigned int hbits;
135	long i, nrec, hsize, bsize;
136	unsigned long hav;
137	char const blk, cur, top, prev;
138	xrecord_t *crec;
139	xrecord_t recs, rrecs;
140	xrecord_t **rhash;
141	unsigned long *ha;
142	char *rchg;
143	long *rindex;
144
145	if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0) {
146
147	return -1;
148	}
149	if (!(recs = (xrecord_t *) xdl_malloc(narec sizeof(xrecord_t *)))) {
150
151	xdl_cha_free(&xdf->rcha);
152	return -1;
153	}
154
155	hbits = xdl_hashbits((unsigned int) narec);
156	hsize = 1 << hbits;
157	if (!(rhash = (xrecord_t *) xdl_malloc(hsize sizeof(xrecord_t *)))) {
158
159	xdl_free(recs);
160	xdl_cha_free(&xdf->rcha);
161	return -1;
162	}
163	for (i = 0; i < hsize; i++)
164	rhash[i] = NULL;
165
166	nrec = 0;
167	if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
168	for (top = blk + bsize;;) {
169	if (cur >= top) {
170	if (!(cur = blk = xdl_mmfile_next(mf, &bsize)))
171	break;
172	top = blk + bsize;
173	}
174	prev = cur;
175	hav = xdl_hash_record(&cur, top);
176	if (nrec >= narec) {
177	narec *= 2;
178	if (!(rrecs = (xrecord_t *) xdl_realloc(recs, narec sizeof(xrecord_t *)))) {
179
180	xdl_free(rhash);
181	xdl_free(recs);
182	xdl_cha_free(&xdf->rcha);
183	return -1;
184	}
185	recs = rrecs;
186	}
187	if (!(crec = xdl_cha_alloc(&xdf->rcha))) {
188
189	xdl_free(rhash);
190	xdl_free(recs);
191	xdl_cha_free(&xdf->rcha);
192	return -1;
193	}
194	crec->ptr = prev;
195	crec->size = (long) (cur - prev);
196	crec->ha = hav;
197	recs[nrec++] = crec;
198
199	if (xdl_classify_record(cf, rhash, hbits, crec) < 0) {
200
201	xdl_free(rhash);
202	xdl_free(recs);
203	xdl_cha_free(&xdf->rcha);
204	return -1;
205	}
206	}
207	}
208
209	if (!(rchg = (char ) xdl_malloc((nrec + 2) sizeof(char)))) {
210
211	xdl_free(rhash);
212	xdl_free(recs);
213	xdl_cha_free(&xdf->rcha);
214	return -1;
215	}
216	memset(rchg, 0, (nrec + 2) * sizeof(char));
217
218	if (!(rindex = (long ) xdl_malloc((nrec + 1) sizeof(long)))) {
219
220	xdl_free(rchg);
221	xdl_free(rhash);
222	xdl_free(recs);
223	xdl_cha_free(&xdf->rcha);
224	return -1;
225	}
226	if (!(ha = (unsigned long ) xdl_malloc((nrec + 1) sizeof(unsigned long)))) {
227
228	xdl_free(rindex);
229	xdl_free(rchg);
230	xdl_free(rhash);
231	xdl_free(recs);
232	xdl_cha_free(&xdf->rcha);
233	return -1;
234	}
235
236	xdf->nrec = nrec;
237	xdf->recs = recs;
238	xdf->hbits = hbits;
239	xdf->rhash = rhash;
240	xdf->rchg = rchg + 1;
241	xdf->rindex = rindex;
242	xdf->nreff = 0;
243	xdf->ha = ha;
244	xdf->dstart = 0;
245	xdf->dend = nrec - 1;
246
247	return 0;
248	}
249
250
251	static void xdl_free_ctx(xdfile_t *xdf) {
252
253	xdl_free(xdf->rhash);
254	xdl_free(xdf->rindex);
255	xdl_free(xdf->rchg - 1);
256	xdl_free(xdf->ha);
257	xdl_free(xdf->recs);
258	xdl_cha_free(&xdf->rcha);
259	}
260
261
262	int xdl_prepare_env(mmfile_t mf1, mmfile_t mf2, xpparam_t const *xpp,
263	xdfenv_t *xe) {
264	long enl1, enl2;
265	xdlclassifier_t cf;
266
267	enl1 = xdl_guess_lines(mf1) + 1;
268	enl2 = xdl_guess_lines(mf2) + 1;
269
270	if (xdl_init_classifier(&cf, enl1 + enl2 + 1) < 0) {
271
272	return -1;
273	}
274
275	if (xdl_prepare_ctx(mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
276
277	xdl_free_classifier(&cf);
278	return -1;
279	}
280	if (xdl_prepare_ctx(mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
281
282	xdl_free_ctx(&xe->xdf1);
283	xdl_free_classifier(&cf);
284	return -1;
285	}
286
287	xdl_free_classifier(&cf);
288
289	if (xdl_optimize_ctxs(&xe->xdf1, &xe->xdf2) < 0) {
290
291	xdl_free_ctx(&xe->xdf2);
292	xdl_free_ctx(&xe->xdf1);
293	return -1;
294	}
295
296	return 0;
297	}
298
299
300	void xdl_free_env(xdfenv_t *xe) {
301
302	xdl_free_ctx(&xe->xdf2);
303	xdl_free_ctx(&xe->xdf1);
304	}
305
306
307	static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
308	long r, rdis, rpdis;
309
310	for (r = 1, rdis = 0, rpdis = 1; (i - r) >= s; r++) {
311	if (!dis[i - r])
312	rdis++;
313	else if (dis[i - r] == 2)
314	rpdis++;
315	else
316	break;
317	}
318	for (r = 1; (i + r) <= e; r++) {
319	if (!dis[i + r])
320	rdis++;
321	else if (dis[i + r] == 2)
322	rpdis++;
323	else
324	break;
325	}
326
327	return rpdis * XDL_KPDIS_RUN < (rpdis + rdis);
328	}
329
330
331	/*
332	* Try to reduce the problem complexity, discard records that have no
333	* matches on the other file. Also, lines that have multiple matches
334	* might be potentially discarded if they happear in a run of discardable.
335	*/
336	static int xdl_cleanup_records(xdfile_t xdf1, xdfile_t xdf2) {
337	long i, rhi, nreff;
338	unsigned long hav;
339	xrecord_t **recs;
340	xrecord_t *rec;
341	char dis, dis1, *dis2;
342
343	if (!(dis = (char ) xdl_malloc((xdf1->nrec + xdf2->nrec + 2) sizeof(char)))) {
344
345	return -1;
346	}
347	memset(dis, 0, (xdf1->nrec + xdf2->nrec + 2) * sizeof(char));
348	dis1 = dis;
349	dis2 = dis1 + xdf1->nrec + 1;
350
351	for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
352	hav = (*recs)->ha;
353	rhi = (long) XDL_HASHLONG(hav, xdf2->hbits);
354	for (rec = xdf2->rhash[rhi]; rec; rec = rec->next)
355	if (rec->ha == hav && ++dis1[i] == 2)
356	break;
357	}
358
359	for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
360	hav = (*recs)->ha;
361	rhi = (long) XDL_HASHLONG(hav, xdf1->hbits);
362	for (rec = xdf1->rhash[rhi]; rec; rec = rec->next)
363	if (rec->ha == hav && ++dis2[i] == 2)
364	break;
365	}
366
367	for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
368	i <= xdf1->dend; i++, recs++) {
369	if (dis1[i] == 1 \|\|
370	(dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
371	xdf1->rindex[nreff] = i;
372	xdf1->ha[nreff] = (*recs)->ha;
373	nreff++;
374	} else
375	xdf1->rchg[i] = 1;
376	}
377	xdf1->nreff = nreff;
378
379	for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
380	i <= xdf2->dend; i++, recs++) {
381	if (dis2[i] == 1 \|\|
382	(dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
383	xdf2->rindex[nreff] = i;
384	xdf2->ha[nreff] = (*recs)->ha;
385	nreff++;
386	} else
387	xdf2->rchg[i] = 1;
388	}
389	xdf2->nreff = nreff;
390
391	xdl_free(dis);
392
393	return 0;
394	}
395
396
397	/*
398	* Early trim initial and terminal matching records.
399	*/
400	static int xdl_trim_ends(xdfile_t xdf1, xdfile_t xdf2) {
401	long i, lim;
402	xrecord_t recs1, recs2;
403
404	recs1 = xdf1->recs;
405	recs2 = xdf2->recs;
406	for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
407	i++, recs1++, recs2++)
408	if ((recs1)->ha != (recs2)->ha)
409	break;
410
411	xdf1->dstart = xdf2->dstart = i;
412
413	recs1 = xdf1->recs + xdf1->nrec - 1;
414	recs2 = xdf2->recs + xdf2->nrec - 1;
415	for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
416	if ((recs1)->ha != (recs2)->ha)
417	break;
418
419	xdf1->dend = xdf1->nrec - i - 1;
420	xdf2->dend = xdf2->nrec - i - 1;
421
422	return 0;
423	}
424
425
426	static int xdl_optimize_ctxs(xdfile_t xdf1, xdfile_t xdf2) {
427
428	if (xdl_trim_ends(xdf1, xdf2) < 0 \|\|
429	xdl_cleanup_records(xdf1, xdf2) < 0) {
430
431	return -1;
432	}
433
434	return 0;
435	}
436