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

/*
 * Copyright (C) 2010, Google Inc.
 * and other copyright owners as documented in JGit's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - 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.
 *
 * - Neither the name of the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, 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 OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "xinclude.h"
#include "xtypes.h"
#include "xdiff.h"

#define MAX_PTR	UINT_MAX
#define MAX_CNT	UINT_MAX

#define LINE_END(n) (line##n + count##n - 1)
#define LINE_END_PTR(n) (*line##n + *count##n - 1)

struct histindex {
	struct record {
		unsigned int ptr, cnt;
		struct record *next;
	} **records, /* an ocurrence */
	  **line_map; /* map of line to record chain */
	chastore_t rcha;
	unsigned int *next_ptrs;
	unsigned int table_bits,
		     records_size,
		     line_map_size;

	unsigned int max_chain_length,
		     key_shift,
		     ptr_shift;

	unsigned int cnt,
		     has_common;

	xdfenv_t *env;
	xpparam_t const *xpp;
};

struct region {
	unsigned int begin1, end1;
	unsigned int begin2, end2;
};

#define LINE_MAP(i, a) (i->line_map[(a) - i->ptr_shift])

#define NEXT_PTR(index, ptr) \
	(index->next_ptrs[(ptr) - index->ptr_shift])

#define CNT(index, ptr) \
	((LINE_MAP(index, ptr))->cnt)

#define REC(env, s, l) \
	(env->xdf##s.recs[l - 1])

static int cmp_recs(xpparam_t const *xpp,
	xrecord_t *r1, xrecord_t *r2)
{
	return r1->ha == r2->ha &&
		xdl_recmatch(r1->ptr, r1->size, r2->ptr, r2->size,
			    xpp->flags);
}

#define CMP_ENV(xpp, env, s1, l1, s2, l2) \
	(cmp_recs(xpp, REC(env, s1, l1), REC(env, s2, l2)))

#define CMP(i, s1, l1, s2, l2) \
	(cmp_recs(i->xpp, REC(i->env, s1, l1), REC(i->env, s2, l2)))

#define TABLE_HASH(index, side, line) \
	XDL_HASHLONG((REC(index->env, side, line))->ha, index->table_bits)

static int scanA(struct histindex *index, int line1, int count1)
{
	unsigned int ptr, tbl_idx;
	unsigned int chain_len;
	struct record **rec_chain, *rec;

	for (ptr = LINE_END(1); line1 <= ptr; ptr--) {
		tbl_idx = TABLE_HASH(index, 1, ptr);
		rec_chain = index->records + tbl_idx;
		rec = *rec_chain;

		chain_len = 0;
		while (rec) {
			if (CMP(index, 1, rec->ptr, 1, ptr)) {
				/*
				 * ptr is identical to another element. Insert
				 * it onto the front of the existing element
				 * chain.
				 */
				NEXT_PTR(index, ptr) = rec->ptr;
				rec->ptr = ptr;
				/* cap rec->cnt at MAX_CNT */
				rec->cnt = XDL_MIN(MAX_CNT, rec->cnt + 1);
				LINE_MAP(index, ptr) = rec;
				goto continue_scan;
			}

			rec = rec->next;
			chain_len++;
		}

		if (chain_len == index->max_chain_length)
			return -1;

		/*
		 * This is the first time we have ever seen this particular
		 * element in the sequence. Construct a new chain for it.
		 */
		if (!(rec = xdl_cha_alloc(&index->rcha)))
			return -1;
		rec->ptr = ptr;
		rec->cnt = 1;
		rec->next = *rec_chain;
		*rec_chain = rec;
		LINE_MAP(index, ptr) = rec;

continue_scan:
		; /* no op */
	}

	return 0;
}

static int try_lcs(struct histindex *index, struct region *lcs, int b_ptr,
	int line1, int count1, int line2, int count2)
{
	unsigned int b_next = b_ptr + 1;
	struct record *rec = index->records[TABLE_HASH(index, 2, b_ptr)];
	unsigned int as, ae, bs, be, np, rc;
	int should_break;

	for (; rec; rec = rec->next) {
		if (rec->cnt > index->cnt) {
			if (!index->has_common)
				index->has_common = CMP(index, 1, rec->ptr, 2, b_ptr);
			continue;
		}

		as = rec->ptr;
		if (!CMP(index, 1, as, 2, b_ptr))
			continue;

		index->has_common = 1;
		for (;;) {
			should_break = 0;
			np = NEXT_PTR(index, as);
			bs = b_ptr;
			ae = as;
			be = bs;
			rc = rec->cnt;

			while (line1 < as && line2 < bs
				&& CMP(index, 1, as - 1, 2, bs - 1)) {
				as--;
				bs--;
				if (1 < rc)
					rc = XDL_MIN(rc, CNT(index, as));
			}
			while (ae < LINE_END(1) && be < LINE_END(2)
				&& CMP(index, 1, ae + 1, 2, be + 1)) {
				ae++;
				be++;
				if (1 < rc)
					rc = XDL_MIN(rc, CNT(index, ae));
			}

			if (b_next <= be)
				b_next = be + 1;
			if (lcs->end1 - lcs->begin1 < ae - as || rc < index->cnt) {
				lcs->begin1 = as;
				lcs->begin2 = bs;
				lcs->end1 = ae;
				lcs->end2 = be;
				index->cnt = rc;
			}

			if (np == 0)
				break;

			while (np <= ae) {
				np = NEXT_PTR(index, np);
				if (np == 0) {
					should_break = 1;
					break;
				}
			}

			if (should_break)
				break;

			as = np;
		}
	}
	return b_next;
}

static int find_lcs(struct histindex *index, struct region *lcs,
	int line1, int count1, int line2, int count2) {
	int b_ptr;

	if (scanA(index, line1, count1))
		return -1;

	index->cnt = index->max_chain_length + 1;

	for (b_ptr = line2; b_ptr <= LINE_END(2); )
		b_ptr = try_lcs(index, lcs, b_ptr, line1, count1, line2, count2);

	return index->has_common && index->max_chain_length < index->cnt;
}

static int fall_back_to_classic_diff(struct histindex *index,
		int line1, int count1, int line2, int count2)
{
	xpparam_t xpp;
	xpp.flags = index->xpp->flags & ~XDF_HISTOGRAM_DIFF;

	return xdl_fall_back_diff(index->env, &xpp,
				  line1, count1, line2, count2);
}

static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
	int line1, int count1, int line2, int count2)
{
	struct histindex index;
	struct region lcs;
	int sz;
	int result = -1;

	if (count1 <= 0 && count2 <= 0)
		return 0;

	if (LINE_END(1) >= MAX_PTR)
		return -1;

	if (!count1) {
		while(count2--)
			env->xdf2.rchg[line2++ - 1] = 1;
		return 0;
	} else if (!count2) {
		while(count1--)
			env->xdf1.rchg[line1++ - 1] = 1;
		return 0;
	}

	memset(&index, 0, sizeof(index));

	index.env = env;
	index.xpp = xpp;

	index.records = NULL;
	index.line_map = NULL;
	/* in case of early xdl_cha_free() */
	index.rcha.head = NULL;

	index.table_bits = xdl_hashbits(count1);
	sz = index.records_size = 1 << index.table_bits;
	sz *= sizeof(struct record *);
	if (!(index.records = (struct record **) xdl_malloc(sz)))
		goto cleanup;
	memset(index.records, 0, sz);

	sz = index.line_map_size = count1;
	sz *= sizeof(struct record *);
	if (!(index.line_map = (struct record **) xdl_malloc(sz)))
		goto cleanup;
	memset(index.line_map, 0, sz);

	sz = index.line_map_size;
	sz *= sizeof(unsigned int);
	if (!(index.next_ptrs = (unsigned int *) xdl_malloc(sz)))
		goto cleanup;
	memset(index.next_ptrs, 0, sz);

	/* lines / 4 + 1 comes from xprepare.c:xdl_prepare_ctx() */
	if (xdl_cha_init(&index.rcha, sizeof(struct record), count1 / 4 + 1) < 0)
		goto cleanup;

	index.ptr_shift = line1;
	index.max_chain_length = 64;

	memset(&lcs, 0, sizeof(lcs));
	if (find_lcs(&index, &lcs, line1, count1, line2, count2))
		result = fall_back_to_classic_diff(&index, line1, count1, line2, count2);
	else {
		if (lcs.begin1 == 0 && lcs.begin2 == 0) {
			while (count1--)
				env->xdf1.rchg[line1++ - 1] = 1;
			while (count2--)
				env->xdf2.rchg[line2++ - 1] = 1;
			result = 0;
		} else {
			result = histogram_diff(xpp, env,
						line1, lcs.begin1 - line1,
						line2, lcs.begin2 - line2);
			if (result)
				goto cleanup;
			result = histogram_diff(xpp, env,
						lcs.end1 + 1, LINE_END(1) - lcs.end1,
						lcs.end2 + 1, LINE_END(2) - lcs.end2);
			if (result)
				goto cleanup;
		}
	}

cleanup:
	xdl_free(index.records);
	xdl_free(index.line_map);
	xdl_free(index.next_ptrs);
	xdl_cha_free(&index.rcha);

	return result;
}

int xdl_do_histogram_diff(mmfile_t *file1, mmfile_t *file2,
	xpparam_t const *xpp, xdfenv_t *env)
{
	if (xdl_prepare_env(file1, file2, xpp, env) < 0)
		return -1;

	return histogram_diff(xpp, env,
		env->xdf1.dstart + 1, env->xdf1.dend - env->xdf1.dstart + 1,
		env->xdf2.dstart + 1, env->xdf2.dend - env->xdf2.dstart + 1);
}
Commit	Line	Data
8c912eea TRC	1	/*
	2	* Copyright (C) 2010, Google Inc.
	3	* and other copyright owners as documented in JGit's IP log.
	4	*
	5	* This program and the accompanying materials are made available
	6	* under the terms of the Eclipse Distribution License v1.0 which
	7	* accompanies this distribution, is reproduced below, and is
	8	* available at http://www.eclipse.org/org/documents/edl-v10.php
	9	*
	10	* All rights reserved.
	11	*
	12	* Redistribution and use in source and binary forms, with or
	13	* without modification, are permitted provided that the following
	14	* conditions are met:
	15	*
	16	* - Redistributions of source code must retain the above copyright
	17	* notice, this list of conditions and the following disclaimer.
	18	*
	19	* - Redistributions in binary form must reproduce the above
	20	* copyright notice, this list of conditions and the following
	21	* disclaimer in the documentation and/or other materials provided
	22	* with the distribution.
	23	*
	24	* - Neither the name of the Eclipse Foundation, Inc. nor the
	25	* names of its contributors may be used to endorse or promote
	26	* products derived from this software without specific prior
	27	* written permission.
	28	*
	29	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
	30	* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
	31	* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	32	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	33	* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
	34	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	35	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	36	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	37	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
	38	* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
	39	* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	40	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
	41	* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	42	*/
	43
	44	#include "xinclude.h"
	45	#include "xtypes.h"
	46	#include "xdiff.h"
	47
	48	#define MAX_PTR UINT_MAX
	49	#define MAX_CNT UINT_MAX
	50
	51	#define LINE_END(n) (line##n + count##n - 1)
	52	#define LINE_END_PTR(n) (line##n + count##n - 1)
	53
	54	struct histindex {
	55	struct record {
	56	unsigned int ptr, cnt;
	57	struct record *next;
	58	} *records, / an ocurrence */
	59	*line_map; / map of line to record chain */
	60	chastore_t rcha;
	61	unsigned int *next_ptrs;
	62	unsigned int table_bits,
	63	records_size,
	64	line_map_size;
65
66	unsigned int max_chain_length,
67	key_shift,
68	ptr_shift;
69
70	unsigned int cnt,
71	has_common;
72
73	xdfenv_t *env;
74	xpparam_t const *xpp;
75	};
76
77	struct region {
78	unsigned int begin1, end1;
79	unsigned int begin2, end2;
80	};
81
82	#define LINE_MAP(i, a) (i->line_map[(a) - i->ptr_shift])
83
84	#define NEXT_PTR(index, ptr) \
85	(index->next_ptrs[(ptr) - index->ptr_shift])
86
87	#define CNT(index, ptr) \
88	((LINE_MAP(index, ptr))->cnt)
89
90	#define REC(env, s, l) \
91	(env->xdf##s.recs[l - 1])
92
93	static int cmp_recs(xpparam_t const *xpp,
94	xrecord_t r1, xrecord_t r2)
95	{
96	return r1->ha == r2->ha &&
97	xdl_recmatch(r1->ptr, r1->size, r2->ptr, r2->size,
98	xpp->flags);
99	}
100
101	#define CMP_ENV(xpp, env, s1, l1, s2, l2) \
102	(cmp_recs(xpp, REC(env, s1, l1), REC(env, s2, l2)))
103
104	#define CMP(i, s1, l1, s2, l2) \
43ca7530	105	(cmp_recs(i->xpp, REC(i->env, s1, l1), REC(i->env, s2, l2)))
8c912eea TRC	106
	107	#define TABLE_HASH(index, side, line) \
	108	XDL_HASHLONG((REC(index->env, side, line))->ha, index->table_bits)
	109
	110	static int scanA(struct histindex *index, int line1, int count1)
	111	{
	112	unsigned int ptr, tbl_idx;
	113	unsigned int chain_len;
	114	struct record *rec_chain, rec;
	115
	116	for (ptr = LINE_END(1); line1 <= ptr; ptr--) {
	117	tbl_idx = TABLE_HASH(index, 1, ptr);
	118	rec_chain = index->records + tbl_idx;
	119	rec = *rec_chain;
	120
	121	chain_len = 0;
	122	while (rec) {
	123	if (CMP(index, 1, rec->ptr, 1, ptr)) {
	124	/*
	125	* ptr is identical to another element. Insert
	126	* it onto the front of the existing element
	127	* chain.
	128	*/
	129	NEXT_PTR(index, ptr) = rec->ptr;
	130	rec->ptr = ptr;
	131	/* cap rec->cnt at MAX_CNT */
	132	rec->cnt = XDL_MIN(MAX_CNT, rec->cnt + 1);
	133	LINE_MAP(index, ptr) = rec;
	134	goto continue_scan;
	135	}
	136
	137	rec = rec->next;
	138	chain_len++;
	139	}
	140
	141	if (chain_len == index->max_chain_length)
	142	return -1;
	143
	144	/*
	145	* This is the first time we have ever seen this particular
	146	* element in the sequence. Construct a new chain for it.
	147	*/
	148	if (!(rec = xdl_cha_alloc(&index->rcha)))
	149	return -1;
	150	rec->ptr = ptr;
	151	rec->cnt = 1;
	152	rec->next = *rec_chain;
	153	*rec_chain = rec;
	154	LINE_MAP(index, ptr) = rec;
	155
	156	continue_scan:
	157	; /* no op */
	158	}
	159
	160	return 0;
	161	}
	162
	163	static int try_lcs(struct histindex index, struct region lcs, int b_ptr,
	164	int line1, int count1, int line2, int count2)
	165	{
	166	unsigned int b_next = b_ptr + 1;
	167	struct record *rec = index->records[TABLE_HASH(index, 2, b_ptr)];
	168	unsigned int as, ae, bs, be, np, rc;
	169	int should_break;
170
171	for (; rec; rec = rec->next) {
172	if (rec->cnt > index->cnt) {
173	if (!index->has_common)
174	index->has_common = CMP(index, 1, rec->ptr, 2, b_ptr);
175	continue;
176	}
177
178	as = rec->ptr;
179	if (!CMP(index, 1, as, 2, b_ptr))
180	continue;
181
182	index->has_common = 1;
183	for (;;) {
184	should_break = 0;
185	np = NEXT_PTR(index, as);
186	bs = b_ptr;
187	ae = as;
188	be = bs;
189	rc = rec->cnt;
190
191	while (line1 < as && line2 < bs
192	&& CMP(index, 1, as - 1, 2, bs - 1)) {
193	as--;
194	bs--;
195	if (1 < rc)
196	rc = XDL_MIN(rc, CNT(index, as));
197	}
198	while (ae < LINE_END(1) && be < LINE_END(2)
199	&& CMP(index, 1, ae + 1, 2, be + 1)) {
200	ae++;
201	be++;
202	if (1 < rc)
203	rc = XDL_MIN(rc, CNT(index, ae));
204	}
205
206	if (b_next <= be)
207	b_next = be + 1;
208	if (lcs->end1 - lcs->begin1 < ae - as \|\| rc < index->cnt) {
209	lcs->begin1 = as;
210	lcs->begin2 = bs;
211	lcs->end1 = ae;
212	lcs->end2 = be;
213	index->cnt = rc;
214	}
215
216	if (np == 0)
217	break;
218
219	while (np <= ae) {
220	np = NEXT_PTR(index, np);
221	if (np == 0) {
222	should_break = 1;
223	break;
224	}
225	}
226
227	if (should_break)
228	break;
229
230	as = np;
231	}
232	}
233	return b_next;
234	}
235
236	static int find_lcs(struct histindex index, struct region lcs,
237	int line1, int count1, int line2, int count2) {
238	int b_ptr;
239
240	if (scanA(index, line1, count1))
241	return -1;
242
243	index->cnt = index->max_chain_length + 1;
244
245	for (b_ptr = line2; b_ptr <= LINE_END(2); )
246	b_ptr = try_lcs(index, lcs, b_ptr, line1, count1, line2, count2);
247
248	return index->has_common && index->max_chain_length < index->cnt;
249	}
250
8c912eea TRC	251	static int fall_back_to_classic_diff(struct histindex *index,
	252	int line1, int count1, int line2, int count2)
	253	{
	254	xpparam_t xpp;
	255	xpp.flags = index->xpp->flags & ~XDF_HISTOGRAM_DIFF;
	256
	257	return xdl_fall_back_diff(index->env, &xpp,
	258	line1, count1, line2, count2);
	259	}
	260
	261	static int histogram_diff(xpparam_t const xpp, xdfenv_t env,
	262	int line1, int count1, int line2, int count2)
	263	{
	264	struct histindex index;
	265	struct region lcs;
	266	int sz;
	267	int result = -1;
	268
	269	if (count1 <= 0 && count2 <= 0)
	270	return 0;
	271
	272	if (LINE_END(1) >= MAX_PTR)
	273	return -1;
	274
	275	if (!count1) {
	276	while(count2--)
	277	env->xdf2.rchg[line2++ - 1] = 1;
	278	return 0;
	279	} else if (!count2) {
	280	while(count1--)
	281	env->xdf1.rchg[line1++ - 1] = 1;
	282	return 0;
	283	}
	284
	285	memset(&index, 0, sizeof(index));
	286
	287	index.env = env;
	288	index.xpp = xpp;
	289
	290	index.records = NULL;
	291	index.line_map = NULL;
	292	/* in case of early xdl_cha_free() */
	293	index.rcha.head = NULL;
	294
	295	index.table_bits = xdl_hashbits(count1);
	296	sz = index.records_size = 1 << index.table_bits;
	297	sz = sizeof(struct record );
	298	if (!(index.records = (struct record **) xdl_malloc(sz)))
	299	goto cleanup;
	300	memset(index.records, 0, sz);
	301
	302	sz = index.line_map_size = count1;
	303	sz = sizeof(struct record );
	304	if (!(index.line_map = (struct record **) xdl_malloc(sz)))
	305	goto cleanup;
	306	memset(index.line_map, 0, sz);
	307
	308	sz = index.line_map_size;
	309	sz *= sizeof(unsigned int);
	310	if (!(index.next_ptrs = (unsigned int *) xdl_malloc(sz)))
	311	goto cleanup;
	312	memset(index.next_ptrs, 0, sz);
	313
	314	/* lines / 4 + 1 comes from xprepare.c:xdl_prepare_ctx() */
315	if (xdl_cha_init(&index.rcha, sizeof(struct record), count1 / 4 + 1) < 0)
316	goto cleanup;
317
318	index.ptr_shift = line1;
319	index.max_chain_length = 64;
320
321	memset(&lcs, 0, sizeof(lcs));
322	if (find_lcs(&index, &lcs, line1, count1, line2, count2))
323	result = fall_back_to_classic_diff(&index, line1, count1, line2, count2);
324	else {
8c912eea	325	if (lcs.begin1 == 0 && lcs.begin2 == 0) {
6486a84c TRC	326	while (count1--)
	327	env->xdf1.rchg[line1++ - 1] = 1;
	328	while (count2--)
	329	env->xdf2.rchg[line2++ - 1] = 1;
19f7a9c5	330	result = 0;
8c912eea TRC	331	} else {
8c912eea TRC	332	result = histogram_diff(xpp, env,
19f7a9c5 TRC	333	line1, lcs.begin1 - line1,
	334	line2, lcs.begin2 - line2);
	335	if (result)
	336	goto cleanup;
8c912eea	337	result = histogram_diff(xpp, env,
19f7a9c5 TRC	338	lcs.end1 + 1, LINE_END(1) - lcs.end1,
	339	lcs.end2 + 1, LINE_END(2) - lcs.end2);
	340	if (result)
	341	goto cleanup;
8c912eea TRC	342	}
	343	}
	344
	345	cleanup:
	346	xdl_free(index.records);
	347	xdl_free(index.line_map);
	348	xdl_free(index.next_ptrs);
	349	xdl_cha_free(&index.rcha);
	350
	351	return result;
	352	}
	353
	354	int xdl_do_histogram_diff(mmfile_t file1, mmfile_t file2,
	355	xpparam_t const xpp, xdfenv_t env)
	356	{
8c912eea TRC	357	if (xdl_prepare_env(file1, file2, xpp, env) < 0)
	358	return -1;
	359
43ca7530 TRC	360	return histogram_diff(xpp, env,
	361	env->xdf1.dstart + 1, env->xdf1.dend - env->xdf1.dstart + 1,
	362	env->xdf2.dstart + 1, env->xdf2.dend - env->xdf2.dstart + 1);
8c912eea	363	}