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* Import 'dummy' mercurial's bdiff (needs to be plugged)
This commit is contained in:
pancake/fluendo
parent
3105b3f137
commit
935d9c1517
397
libr/diff/bdiff.c
Normal file
397
libr/diff/bdiff.c
Normal file
@ -0,0 +1,397 @@
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/*
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bdiff.c - efficient binary diff extension for Mercurial
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Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
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This software may be used and distributed according to the terms of
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the GNU General Public License, incorporated herein by reference.
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Based roughly on Python difflib
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*/
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#include <Python.h>
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#include <stdlib.h>
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#include <string.h>
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#include <limits.h>
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#if defined __hpux || defined __SUNPRO_C || defined _AIX
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# define inline
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#endif
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#ifdef _WIN32
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#ifdef _MSC_VER
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#define inline __inline
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typedef unsigned long uint32_t;
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#else
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#include <stdint.h>
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#endif
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static uint32_t htonl(uint32_t x)
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{
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return ((x & 0x000000ffUL) << 24) |
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((x & 0x0000ff00UL) << 8) |
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((x & 0x00ff0000UL) >> 8) |
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((x & 0xff000000UL) >> 24);
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}
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#else
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#include <sys/types.h>
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#if defined __BEOS__ && !defined __HAIKU__
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#include <ByteOrder.h>
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#else
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#include <arpa/inet.h>
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#endif
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#include <inttypes.h>
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#endif
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struct line {
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int h, len, n, e;
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const char *l;
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};
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struct pos {
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int pos, len;
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};
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struct hunk {
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int a1, a2, b1, b2;
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};
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struct hunklist {
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struct hunk *base, *head;
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};
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int splitlines(const char *a, int len, struct line **lr)
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{
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int h, i;
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const char *p, *b = a;
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const char * const plast = a + len - 1;
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struct line *l;
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/* count the lines */
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i = 1; /* extra line for sentinel */
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for (p = a; p < a + len; p++)
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if (*p == '\n' || p == plast)
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i++;
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*lr = l = (struct line *)malloc(sizeof(struct line) * i);
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if (!l)
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return -1;
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/* build the line array and calculate hashes */
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h = 0;
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for (p = a; p < a + len; p++) {
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/* Leonid Yuriev's hash */
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h = (h * 1664525) + *p + 1013904223;
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if (*p == '\n' || p == plast) {
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l->h = h;
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h = 0;
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l->len = p - b + 1;
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l->l = b;
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l->n = INT_MAX;
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l++;
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b = p + 1;
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}
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}
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/* set up a sentinel */
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l->h = l->len = 0;
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l->l = a + len;
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return i - 1;
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}
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int inline cmp(struct line *a, struct line *b)
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{
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return a->h != b->h || a->len != b->len || memcmp(a->l, b->l, a->len);
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}
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static int equatelines(struct line *a, int an, struct line *b, int bn)
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{
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int i, j, buckets = 1, t, scale;
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struct pos *h = NULL;
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/* build a hash table of the next highest power of 2 */
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while (buckets < bn + 1)
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buckets *= 2;
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/* try to allocate a large hash table to avoid collisions */
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for (scale = 4; scale; scale /= 2) {
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h = (struct pos *)malloc(scale * buckets * sizeof(struct pos));
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if (h)
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break;
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}
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if (!h)
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return 0;
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buckets = buckets * scale - 1;
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/* clear the hash table */
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for (i = 0; i <= buckets; i++) {
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h[i].pos = INT_MAX;
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h[i].len = 0;
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}
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/* add lines to the hash table chains */
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for (i = bn - 1; i >= 0; i--) {
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/* find the equivalence class */
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for (j = b[i].h & buckets; h[j].pos != INT_MAX;
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j = (j + 1) & buckets)
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if (!cmp(b + i, b + h[j].pos))
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break;
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/* add to the head of the equivalence class */
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b[i].n = h[j].pos;
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b[i].e = j;
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h[j].pos = i;
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h[j].len++; /* keep track of popularity */
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}
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/* compute popularity threshold */
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t = (bn >= 4000) ? bn / 1000 : bn + 1;
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/* match items in a to their equivalence class in b */
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for (i = 0; i < an; i++) {
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/* find the equivalence class */
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for (j = a[i].h & buckets; h[j].pos != INT_MAX;
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j = (j + 1) & buckets)
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if (!cmp(a + i, b + h[j].pos))
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break;
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a[i].e = j; /* use equivalence class for quick compare */
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if (h[j].len <= t)
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a[i].n = h[j].pos; /* point to head of match list */
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else
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a[i].n = INT_MAX; /* too popular */
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}
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/* discard hash tables */
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free(h);
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return 1;
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}
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static int longest_match(struct line *a, struct line *b, struct pos *pos,
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int a1, int a2, int b1, int b2, int *omi, int *omj)
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{
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int mi = a1, mj = b1, mk = 0, mb = 0, i, j, k;
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for (i = a1; i < a2; i++) {
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/* skip things before the current block */
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for (j = a[i].n; j < b1; j = b[j].n)
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;
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/* loop through all lines match a[i] in b */
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for (; j < b2; j = b[j].n) {
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/* does this extend an earlier match? */
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if (i > a1 && j > b1 && pos[j - 1].pos == i - 1)
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k = pos[j - 1].len + 1;
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else
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k = 1;
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pos[j].pos = i;
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pos[j].len = k;
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/* best match so far? */
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if (k > mk) {
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mi = i;
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mj = j;
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mk = k;
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}
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}
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}
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if (mk) {
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mi = mi - mk + 1;
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mj = mj - mk + 1;
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}
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/* expand match to include neighboring popular lines */
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while (mi - mb > a1 && mj - mb > b1 &&
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a[mi - mb - 1].e == b[mj - mb - 1].e)
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mb++;
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while (mi + mk < a2 && mj + mk < b2 &&
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a[mi + mk].e == b[mj + mk].e)
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mk++;
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*omi = mi - mb;
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*omj = mj - mb;
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return mk + mb;
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}
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static void recurse(struct line *a, struct line *b, struct pos *pos,
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int a1, int a2, int b1, int b2, struct hunklist *l)
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{
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int i, j, k;
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/* find the longest match in this chunk */
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k = longest_match(a, b, pos, a1, a2, b1, b2, &i, &j);
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if (!k)
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return;
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/* and recurse on the remaining chunks on either side */
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recurse(a, b, pos, a1, i, b1, j, l);
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l->head->a1 = i;
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l->head->a2 = i + k;
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l->head->b1 = j;
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l->head->b2 = j + k;
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l->head++;
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recurse(a, b, pos, i + k, a2, j + k, b2, l);
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}
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static struct hunklist diff(struct line *a, int an, struct line *b, int bn)
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{
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struct hunklist l;
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struct hunk *curr;
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struct pos *pos;
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int t;
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/* allocate and fill arrays */
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t = equatelines(a, an, b, bn);
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pos = (struct pos *)calloc(bn ? bn : 1, sizeof(struct pos));
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/* we can't have more matches than lines in the shorter file */
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l.head = l.base = (struct hunk *)malloc(sizeof(struct hunk) *
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((an<bn ? an:bn) + 1));
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if (pos && l.base && t) {
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/* generate the matching block list */
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recurse(a, b, pos, 0, an, 0, bn, &l);
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l.head->a1 = l.head->a2 = an;
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l.head->b1 = l.head->b2 = bn;
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l.head++;
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}
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free(pos);
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/* normalize the hunk list, try to push each hunk towards the end */
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for (curr = l.base; curr != l.head; curr++) {
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struct hunk *next = curr+1;
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int shift = 0;
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if (next == l.head)
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break;
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if (curr->a2 == next->a1)
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while (curr->a2+shift < an && curr->b2+shift < bn
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&& !cmp(a+curr->a2+shift, b+curr->b2+shift))
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shift++;
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else if (curr->b2 == next->b1)
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while (curr->b2+shift < bn && curr->a2+shift < an
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&& !cmp(b+curr->b2+shift, a+curr->a2+shift))
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shift++;
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if (!shift)
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continue;
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curr->b2 += shift;
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next->b1 += shift;
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curr->a2 += shift;
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next->a1 += shift;
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}
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return l;
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}
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static PyObject *blocks(PyObject *self, PyObject *args)
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{
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PyObject *sa, *sb, *rl = NULL, *m;
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struct line *a, *b;
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struct hunklist l = {NULL, NULL};
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struct hunk *h;
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int an, bn, pos = 0;
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if (!PyArg_ParseTuple(args, "SS:bdiff", &sa, &sb))
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return NULL;
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an = splitlines(PyString_AsString(sa), PyString_Size(sa), &a);
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bn = splitlines(PyString_AsString(sb), PyString_Size(sb), &b);
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if (!a || !b)
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goto nomem;
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l = diff(a, an, b, bn);
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rl = PyList_New(l.head - l.base);
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if (!l.head || !rl)
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goto nomem;
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for (h = l.base; h != l.head; h++) {
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m = Py_BuildValue("iiii", h->a1, h->a2, h->b1, h->b2);
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PyList_SetItem(rl, pos, m);
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pos++;
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}
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nomem:
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free(a);
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free(b);
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free(l.base);
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return rl ? rl : PyErr_NoMemory();
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}
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static PyObject *bdiff(PyObject *self, PyObject *args)
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{
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char *sa, *sb;
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PyObject *result = NULL;
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struct line *al, *bl;
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struct hunklist l = {NULL, NULL};
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struct hunk *h;
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char encode[12], *rb;
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int an, bn, len = 0, la, lb;
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if (!PyArg_ParseTuple(args, "s#s#:bdiff", &sa, &la, &sb, &lb))
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return NULL;
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an = splitlines(sa, la, &al);
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bn = splitlines(sb, lb, &bl);
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if (!al || !bl)
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goto nomem;
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l = diff(al, an, bl, bn);
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if (!l.head)
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goto nomem;
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/* calculate length of output */
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la = lb = 0;
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for (h = l.base; h != l.head; h++) {
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if (h->a1 != la || h->b1 != lb)
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len += 12 + bl[h->b1].l - bl[lb].l;
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la = h->a2;
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lb = h->b2;
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}
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result = PyString_FromStringAndSize(NULL, len);
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if (!result)
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goto nomem;
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/* build binary patch */
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rb = PyString_AsString(result);
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la = lb = 0;
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for (h = l.base; h != l.head; h++) {
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if (h->a1 != la || h->b1 != lb) {
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len = bl[h->b1].l - bl[lb].l;
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*(uint32_t *)(encode) = htonl(al[la].l - al->l);
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*(uint32_t *)(encode + 4) = htonl(al[h->a1].l - al->l);
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*(uint32_t *)(encode + 8) = htonl(len);
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memcpy(rb, encode, 12);
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memcpy(rb + 12, bl[lb].l, len);
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rb += 12 + len;
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}
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la = h->a2;
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lb = h->b2;
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}
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nomem:
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free(al);
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free(bl);
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free(l.base);
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return result ? result : PyErr_NoMemory();
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}
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static char mdiff_doc[] = "Efficient binary diff.";
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static PyMethodDef methods[] = {
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{"bdiff", bdiff, METH_VARARGS, "calculate a binary diff\n"},
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{"blocks", blocks, METH_VARARGS, "find a list of matching lines\n"},
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{NULL, NULL}
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};
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PyMODINIT_FUNC initbdiff(void)
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{
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Py_InitModule3("bdiff", methods, mdiff_doc);
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}
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