Merge branch 'nd/stream-to-archive'
[git.git] / xdiff / xutils.c
blob1b3b471ac86a30474e3acabea3d2df3b6da072d8
1 /*
2 * LibXDiff by Davide Libenzi ( File Differential Library )
3 * Copyright (C) 2003 Davide Libenzi
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2.1 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 * Davide Libenzi <davidel@xmailserver.org>
23 #include <limits.h>
24 #include <assert.h>
25 #include "xinclude.h"
30 long xdl_bogosqrt(long n) {
31 long i;
34 * Classical integer square root approximation using shifts.
36 for (i = 1; n > 0; n >>= 2)
37 i <<= 1;
39 return i;
43 int xdl_emit_diffrec(char const *rec, long size, char const *pre, long psize,
44 xdemitcb_t *ecb) {
45 int i = 2;
46 mmbuffer_t mb[3];
48 mb[0].ptr = (char *) pre;
49 mb[0].size = psize;
50 mb[1].ptr = (char *) rec;
51 mb[1].size = size;
52 if (size > 0 && rec[size - 1] != '\n') {
53 mb[2].ptr = (char *) "\n\\ No newline at end of file\n";
54 mb[2].size = strlen(mb[2].ptr);
55 i++;
57 if (ecb->outf(ecb->priv, mb, i) < 0) {
59 return -1;
62 return 0;
65 void *xdl_mmfile_first(mmfile_t *mmf, long *size)
67 *size = mmf->size;
68 return mmf->ptr;
72 long xdl_mmfile_size(mmfile_t *mmf)
74 return mmf->size;
78 int xdl_cha_init(chastore_t *cha, long isize, long icount) {
80 cha->head = cha->tail = NULL;
81 cha->isize = isize;
82 cha->nsize = icount * isize;
83 cha->ancur = cha->sncur = NULL;
84 cha->scurr = 0;
86 return 0;
90 void xdl_cha_free(chastore_t *cha) {
91 chanode_t *cur, *tmp;
93 for (cur = cha->head; (tmp = cur) != NULL;) {
94 cur = cur->next;
95 xdl_free(tmp);
100 void *xdl_cha_alloc(chastore_t *cha) {
101 chanode_t *ancur;
102 void *data;
104 if (!(ancur = cha->ancur) || ancur->icurr == cha->nsize) {
105 if (!(ancur = (chanode_t *) xdl_malloc(sizeof(chanode_t) + cha->nsize))) {
107 return NULL;
109 ancur->icurr = 0;
110 ancur->next = NULL;
111 if (cha->tail)
112 cha->tail->next = ancur;
113 if (!cha->head)
114 cha->head = ancur;
115 cha->tail = ancur;
116 cha->ancur = ancur;
119 data = (char *) ancur + sizeof(chanode_t) + ancur->icurr;
120 ancur->icurr += cha->isize;
122 return data;
126 void *xdl_cha_first(chastore_t *cha) {
127 chanode_t *sncur;
129 if (!(cha->sncur = sncur = cha->head))
130 return NULL;
132 cha->scurr = 0;
134 return (char *) sncur + sizeof(chanode_t) + cha->scurr;
138 void *xdl_cha_next(chastore_t *cha) {
139 chanode_t *sncur;
141 if (!(sncur = cha->sncur))
142 return NULL;
143 cha->scurr += cha->isize;
144 if (cha->scurr == sncur->icurr) {
145 if (!(sncur = cha->sncur = sncur->next))
146 return NULL;
147 cha->scurr = 0;
150 return (char *) sncur + sizeof(chanode_t) + cha->scurr;
154 long xdl_guess_lines(mmfile_t *mf, long sample) {
155 long nl = 0, size, tsize = 0;
156 char const *data, *cur, *top;
158 if ((cur = data = xdl_mmfile_first(mf, &size)) != NULL) {
159 for (top = data + size; nl < sample && cur < top; ) {
160 nl++;
161 if (!(cur = memchr(cur, '\n', top - cur)))
162 cur = top;
163 else
164 cur++;
166 tsize += (long) (cur - data);
169 if (nl && tsize)
170 nl = xdl_mmfile_size(mf) / (tsize / nl);
172 return nl + 1;
175 int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags)
177 int i1, i2;
179 if (s1 == s2 && !memcmp(l1, l2, s1))
180 return 1;
181 if (!(flags & XDF_WHITESPACE_FLAGS))
182 return 0;
184 i1 = 0;
185 i2 = 0;
188 * -w matches everything that matches with -b, and -b in turn
189 * matches everything that matches with --ignore-space-at-eol.
191 * Each flavor of ignoring needs different logic to skip whitespaces
192 * while we have both sides to compare.
194 if (flags & XDF_IGNORE_WHITESPACE) {
195 goto skip_ws;
196 while (i1 < s1 && i2 < s2) {
197 if (l1[i1++] != l2[i2++])
198 return 0;
199 skip_ws:
200 while (i1 < s1 && XDL_ISSPACE(l1[i1]))
201 i1++;
202 while (i2 < s2 && XDL_ISSPACE(l2[i2]))
203 i2++;
205 } else if (flags & XDF_IGNORE_WHITESPACE_CHANGE) {
206 while (i1 < s1 && i2 < s2) {
207 if (XDL_ISSPACE(l1[i1]) && XDL_ISSPACE(l2[i2])) {
208 /* Skip matching spaces and try again */
209 while (i1 < s1 && XDL_ISSPACE(l1[i1]))
210 i1++;
211 while (i2 < s2 && XDL_ISSPACE(l2[i2]))
212 i2++;
213 continue;
215 if (l1[i1++] != l2[i2++])
216 return 0;
218 } else if (flags & XDF_IGNORE_WHITESPACE_AT_EOL) {
219 while (i1 < s1 && i2 < s2 && l1[i1++] == l2[i2++])
220 ; /* keep going */
224 * After running out of one side, the remaining side must have
225 * nothing but whitespace for the lines to match. Note that
226 * ignore-whitespace-at-eol case may break out of the loop
227 * while there still are characters remaining on both lines.
229 if (i1 < s1) {
230 while (i1 < s1 && XDL_ISSPACE(l1[i1]))
231 i1++;
232 if (s1 != i1)
233 return 0;
235 if (i2 < s2) {
236 while (i2 < s2 && XDL_ISSPACE(l2[i2]))
237 i2++;
238 return (s2 == i2);
240 return 1;
243 static unsigned long xdl_hash_record_with_whitespace(char const **data,
244 char const *top, long flags) {
245 unsigned long ha = 5381;
246 char const *ptr = *data;
248 for (; ptr < top && *ptr != '\n'; ptr++) {
249 if (XDL_ISSPACE(*ptr)) {
250 const char *ptr2 = ptr;
251 int at_eol;
252 while (ptr + 1 < top && XDL_ISSPACE(ptr[1])
253 && ptr[1] != '\n')
254 ptr++;
255 at_eol = (top <= ptr + 1 || ptr[1] == '\n');
256 if (flags & XDF_IGNORE_WHITESPACE)
257 ; /* already handled */
258 else if (flags & XDF_IGNORE_WHITESPACE_CHANGE
259 && !at_eol) {
260 ha += (ha << 5);
261 ha ^= (unsigned long) ' ';
263 else if (flags & XDF_IGNORE_WHITESPACE_AT_EOL
264 && !at_eol) {
265 while (ptr2 != ptr + 1) {
266 ha += (ha << 5);
267 ha ^= (unsigned long) *ptr2;
268 ptr2++;
271 continue;
273 ha += (ha << 5);
274 ha ^= (unsigned long) *ptr;
276 *data = ptr < top ? ptr + 1: ptr;
278 return ha;
281 #ifdef XDL_FAST_HASH
283 #define ONEBYTES 0x0101010101010101ul
284 #define NEWLINEBYTES 0x0a0a0a0a0a0a0a0aul
285 #define HIGHBITS 0x8080808080808080ul
287 /* Return the high bit set in the first byte that is a zero */
288 static inline unsigned long has_zero(unsigned long a)
290 return ((a - ONEBYTES) & ~a) & HIGHBITS;
293 static inline long count_masked_bytes(unsigned long mask)
295 if (sizeof(long) == 8) {
297 * Jan Achrenius on G+: microoptimized version of
298 * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
299 * that works for the bytemasks without having to
300 * mask them first.
302 return mask * 0x0001020304050608 >> 56;
303 } else {
305 * Modified Carl Chatfield G+ version for 32-bit *
307 * (a) gives us
308 * -1 (0, ff), 0 (ffff) or 1 (ffffff)
309 * (b) gives us
310 * 0 for 0, 1 for (ff ffff ffffff)
311 * (a+b+1) gives us
312 * correct 0-3 bytemask count result
314 long a = (mask - 256) >> 23;
315 long b = mask & 1;
316 return a + b + 1;
320 unsigned long xdl_hash_record(char const **data, char const *top, long flags)
322 unsigned long hash = 5381;
323 unsigned long a = 0, mask = 0;
324 char const *ptr = *data;
325 char const *end = top - sizeof(unsigned long) + 1;
327 if (flags & XDF_WHITESPACE_FLAGS)
328 return xdl_hash_record_with_whitespace(data, top, flags);
330 ptr -= sizeof(unsigned long);
331 do {
332 hash += hash << 5;
333 hash ^= a;
334 ptr += sizeof(unsigned long);
335 if (ptr >= end)
336 break;
337 a = *(unsigned long *)ptr;
338 /* Do we have any '\n' bytes in this word? */
339 mask = has_zero(a ^ NEWLINEBYTES);
340 } while (!mask);
342 if (ptr >= end) {
344 * There is only a partial word left at the end of the
345 * buffer. Because we may work with a memory mapping,
346 * we have to grab the rest byte by byte instead of
347 * blindly reading it.
349 * To avoid problems with masking in a signed value,
350 * we use an unsigned char here.
352 const char *p;
353 for (p = top - 1; p >= ptr; p--)
354 a = (a << 8) + *((const unsigned char *)p);
355 mask = has_zero(a ^ NEWLINEBYTES);
356 if (!mask)
358 * No '\n' found in the partial word. Make a
359 * mask that matches what we read.
361 mask = 1UL << (8 * (top - ptr) + 7);
364 /* The mask *below* the first high bit set */
365 mask = (mask - 1) & ~mask;
366 mask >>= 7;
367 hash += hash << 5;
368 hash ^= a & mask;
370 /* Advance past the last (possibly partial) word */
371 ptr += count_masked_bytes(mask);
373 if (ptr < top) {
374 assert(*ptr == '\n');
375 ptr++;
378 *data = ptr;
380 return hash;
383 #else /* XDL_FAST_HASH */
385 unsigned long xdl_hash_record(char const **data, char const *top, long flags) {
386 unsigned long ha = 5381;
387 char const *ptr = *data;
389 if (flags & XDF_WHITESPACE_FLAGS)
390 return xdl_hash_record_with_whitespace(data, top, flags);
392 for (; ptr < top && *ptr != '\n'; ptr++) {
393 ha += (ha << 5);
394 ha ^= (unsigned long) *ptr;
396 *data = ptr < top ? ptr + 1: ptr;
398 return ha;
401 #endif /* XDL_FAST_HASH */
403 unsigned int xdl_hashbits(unsigned int size) {
404 unsigned int val = 1, bits = 0;
406 for (; val < size && bits < CHAR_BIT * sizeof(unsigned int); val <<= 1, bits++);
407 return bits ? bits: 1;
411 int xdl_num_out(char *out, long val) {
412 char *ptr, *str = out;
413 char buf[32];
415 ptr = buf + sizeof(buf) - 1;
416 *ptr = '\0';
417 if (val < 0) {
418 *--ptr = '-';
419 val = -val;
421 for (; val && ptr > buf; val /= 10)
422 *--ptr = "0123456789"[val % 10];
423 if (*ptr)
424 for (; *ptr; ptr++, str++)
425 *str = *ptr;
426 else
427 *str++ = '0';
428 *str = '\0';
430 return str - out;
434 long xdl_atol(char const *str, char const **next) {
435 long val, base;
436 char const *top;
438 for (top = str; XDL_ISDIGIT(*top); top++);
439 if (next)
440 *next = top;
441 for (val = 0, base = 1, top--; top >= str; top--, base *= 10)
442 val += base * (long)(*top - '0');
443 return val;
447 int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
448 const char *func, long funclen, xdemitcb_t *ecb) {
449 int nb = 0;
450 mmbuffer_t mb;
451 char buf[128];
453 memcpy(buf, "@@ -", 4);
454 nb += 4;
456 nb += xdl_num_out(buf + nb, c1 ? s1: s1 - 1);
458 if (c1 != 1) {
459 memcpy(buf + nb, ",", 1);
460 nb += 1;
462 nb += xdl_num_out(buf + nb, c1);
465 memcpy(buf + nb, " +", 2);
466 nb += 2;
468 nb += xdl_num_out(buf + nb, c2 ? s2: s2 - 1);
470 if (c2 != 1) {
471 memcpy(buf + nb, ",", 1);
472 nb += 1;
474 nb += xdl_num_out(buf + nb, c2);
477 memcpy(buf + nb, " @@", 3);
478 nb += 3;
479 if (func && funclen) {
480 buf[nb++] = ' ';
481 if (funclen > sizeof(buf) - nb - 1)
482 funclen = sizeof(buf) - nb - 1;
483 memcpy(buf + nb, func, funclen);
484 nb += funclen;
486 buf[nb++] = '\n';
488 mb.ptr = buf;
489 mb.size = nb;
490 if (ecb->outf(ecb->priv, &mb, 1) < 0)
491 return -1;
493 return 0;
496 int xdl_fall_back_diff(xdfenv_t *diff_env, xpparam_t const *xpp,
497 int line1, int count1, int line2, int count2)
500 * This probably does not work outside Git, since
501 * we have a very simple mmfile structure.
503 * Note: ideally, we would reuse the prepared environment, but
504 * the libxdiff interface does not (yet) allow for diffing only
505 * ranges of lines instead of the whole files.
507 mmfile_t subfile1, subfile2;
508 xdfenv_t env;
510 subfile1.ptr = (char *)diff_env->xdf1.recs[line1 - 1]->ptr;
511 subfile1.size = diff_env->xdf1.recs[line1 + count1 - 2]->ptr +
512 diff_env->xdf1.recs[line1 + count1 - 2]->size - subfile1.ptr;
513 subfile2.ptr = (char *)diff_env->xdf2.recs[line2 - 1]->ptr;
514 subfile2.size = diff_env->xdf2.recs[line2 + count2 - 2]->ptr +
515 diff_env->xdf2.recs[line2 + count2 - 2]->size - subfile2.ptr;
516 if (xdl_do_diff(&subfile1, &subfile2, xpp, &env) < 0)
517 return -1;
519 memcpy(diff_env->xdf1.rchg + line1 - 1, env.xdf1.rchg, count1);
520 memcpy(diff_env->xdf2.rchg + line2 - 1, env.xdf2.rchg, count2);
522 xdl_free_env(&env);
524 return 0;