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-rw-r--r--src/xdiff/xhistogram.c386
1 files changed, 386 insertions, 0 deletions
diff --git a/src/xdiff/xhistogram.c b/src/xdiff/xhistogram.c
new file mode 100644
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--- /dev/null
+++ b/src/xdiff/xhistogram.c
@@ -0,0 +1,386 @@
+/*
+ * 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 INT_MAX
+#define MAX_CNT INT_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 occurrence
+ **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)
+{
+ 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 < (int)as && line2 < (int)bs
+ && CMP(index, 1, as - 1, 2, bs - 1)) {
+ as--;
+ bs--;
+ if (1 < rc)
+ rc = XDL_MIN(rc, CNT(index, as));
+ }
+ while ((int)ae < LINE_END(1) && (int)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 fall_back_to_classic_diff(xpparam_t const *xpp, xdfenv_t *env,
+ int line1, int count1, int line2, int count2)
+{
+ xpparam_t xpparam;
+ xpparam.flags = xpp->flags & ~XDF_DIFF_ALGORITHM_MASK;
+
+ return xdl_fall_back_diff(env, &xpparam,
+ line1, count1, line2, count2);
+}
+
+static inline void free_index(struct histindex *index)
+{
+ xdl_free(index->records);
+ xdl_free(index->line_map);
+ xdl_free(index->next_ptrs);
+ xdl_cha_free(&index->rcha);
+}
+
+static int find_lcs(xpparam_t const *xpp, xdfenv_t *env,
+ struct region *lcs,
+ int line1, int count1, int line2, int count2)
+{
+ int b_ptr;
+ int sz, ret = -1;
+ struct histindex index;
+
+ 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;
+
+ if (scanA(&index, line1, count1))
+ goto cleanup;
+
+ 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);
+
+ if (index.has_common && index.max_chain_length < index.cnt)
+ ret = 1;
+ else
+ ret = 0;
+
+cleanup:
+ free_index(&index);
+ return ret;
+}
+
+static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
+ int line1, int count1, int line2, int count2)
+{
+ struct region lcs;
+ int lcs_found;
+ int result;
+redo:
+ 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(&lcs, 0, sizeof(lcs));
+ lcs_found = find_lcs(xpp, env, &lcs, line1, count1, line2, count2);
+ if (lcs_found < 0)
+ goto out;
+ else if (lcs_found)
+ result = fall_back_to_classic_diff(xpp, env, 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 out;
+ /*
+ * result = histogram_diff(xpp, env,
+ * lcs.end1 + 1, LINE_END(1) - lcs.end1,
+ * lcs.end2 + 1, LINE_END(2) - lcs.end2);
+ * but let's optimize tail recursion ourself:
+ */
+ count1 = LINE_END(1) - lcs.end1;
+ line1 = lcs.end1 + 1;
+ count2 = LINE_END(2) - lcs.end2;
+ line2 = lcs.end2 + 1;
+ goto redo;
+ }
+ }
+out:
+ 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);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-12 03:30:01 +0000