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/*
* 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_DIFF_ALGORITHM_MASK;
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);
}
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