From aed8ce9da277f5ecffe968b324f242c41c3b752a Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 10:50:31 +0200 Subject: Adding upstream version 2:9.0.1378. Signed-off-by: Daniel Baumann --- src/xdiff/xhistogram.c | 386 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 386 insertions(+) create mode 100644 src/xdiff/xhistogram.c (limited to 'src/xdiff/xhistogram.c') diff --git a/src/xdiff/xhistogram.c b/src/xdiff/xhistogram.c new file mode 100644 index 0000000..8598a85 --- /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" + +#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; + + memset(&xpparam, 0, sizeof(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); +} -- cgit v1.2.3