git/xdiff/xutils.c
Junio C Hamano 0bc8bea2b4 Merge branch 'rs/xdiff-fast-hash-fix'
Fixes compilation issue on 32-bit in an earlier series.
2012-05-25 12:05:02 -07:00

483 lines
11 KiB
C

/*
* LibXDiff by Davide Libenzi ( File Differential Library )
* Copyright (C) 2003 Davide Libenzi
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Davide Libenzi <davidel@xmailserver.org>
*
*/
#include <limits.h>
#include <assert.h>
#include "xinclude.h"
long xdl_bogosqrt(long n) {
long i;
/*
* Classical integer square root approximation using shifts.
*/
for (i = 1; n > 0; n >>= 2)
i <<= 1;
return i;
}
int xdl_emit_diffrec(char const *rec, long size, char const *pre, long psize,
xdemitcb_t *ecb) {
int i = 2;
mmbuffer_t mb[3];
mb[0].ptr = (char *) pre;
mb[0].size = psize;
mb[1].ptr = (char *) rec;
mb[1].size = size;
if (size > 0 && rec[size - 1] != '\n') {
mb[2].ptr = (char *) "\n\\ No newline at end of file\n";
mb[2].size = strlen(mb[2].ptr);
i++;
}
if (ecb->outf(ecb->priv, mb, i) < 0) {
return -1;
}
return 0;
}
void *xdl_mmfile_first(mmfile_t *mmf, long *size)
{
*size = mmf->size;
return mmf->ptr;
}
long xdl_mmfile_size(mmfile_t *mmf)
{
return mmf->size;
}
int xdl_cha_init(chastore_t *cha, long isize, long icount) {
cha->head = cha->tail = NULL;
cha->isize = isize;
cha->nsize = icount * isize;
cha->ancur = cha->sncur = NULL;
cha->scurr = 0;
return 0;
}
void xdl_cha_free(chastore_t *cha) {
chanode_t *cur, *tmp;
for (cur = cha->head; (tmp = cur) != NULL;) {
cur = cur->next;
xdl_free(tmp);
}
}
void *xdl_cha_alloc(chastore_t *cha) {
chanode_t *ancur;
void *data;
if (!(ancur = cha->ancur) || ancur->icurr == cha->nsize) {
if (!(ancur = (chanode_t *) xdl_malloc(sizeof(chanode_t) + cha->nsize))) {
return NULL;
}
ancur->icurr = 0;
ancur->next = NULL;
if (cha->tail)
cha->tail->next = ancur;
if (!cha->head)
cha->head = ancur;
cha->tail = ancur;
cha->ancur = ancur;
}
data = (char *) ancur + sizeof(chanode_t) + ancur->icurr;
ancur->icurr += cha->isize;
return data;
}
long xdl_guess_lines(mmfile_t *mf, long sample) {
long nl = 0, size, tsize = 0;
char const *data, *cur, *top;
if ((cur = data = xdl_mmfile_first(mf, &size)) != NULL) {
for (top = data + size; nl < sample && cur < top; ) {
nl++;
if (!(cur = memchr(cur, '\n', top - cur)))
cur = top;
else
cur++;
}
tsize += (long) (cur - data);
}
if (nl && tsize)
nl = xdl_mmfile_size(mf) / (tsize / nl);
return nl + 1;
}
int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags)
{
int i1, i2;
if (s1 == s2 && !memcmp(l1, l2, s1))
return 1;
if (!(flags & XDF_WHITESPACE_FLAGS))
return 0;
i1 = 0;
i2 = 0;
/*
* -w matches everything that matches with -b, and -b in turn
* matches everything that matches with --ignore-space-at-eol.
*
* Each flavor of ignoring needs different logic to skip whitespaces
* while we have both sides to compare.
*/
if (flags & XDF_IGNORE_WHITESPACE) {
goto skip_ws;
while (i1 < s1 && i2 < s2) {
if (l1[i1++] != l2[i2++])
return 0;
skip_ws:
while (i1 < s1 && XDL_ISSPACE(l1[i1]))
i1++;
while (i2 < s2 && XDL_ISSPACE(l2[i2]))
i2++;
}
} else if (flags & XDF_IGNORE_WHITESPACE_CHANGE) {
while (i1 < s1 && i2 < s2) {
if (XDL_ISSPACE(l1[i1]) && XDL_ISSPACE(l2[i2])) {
/* Skip matching spaces and try again */
while (i1 < s1 && XDL_ISSPACE(l1[i1]))
i1++;
while (i2 < s2 && XDL_ISSPACE(l2[i2]))
i2++;
continue;
}
if (l1[i1++] != l2[i2++])
return 0;
}
} else if (flags & XDF_IGNORE_WHITESPACE_AT_EOL) {
while (i1 < s1 && i2 < s2 && l1[i1++] == l2[i2++])
; /* keep going */
}
/*
* After running out of one side, the remaining side must have
* nothing but whitespace for the lines to match. Note that
* ignore-whitespace-at-eol case may break out of the loop
* while there still are characters remaining on both lines.
*/
if (i1 < s1) {
while (i1 < s1 && XDL_ISSPACE(l1[i1]))
i1++;
if (s1 != i1)
return 0;
}
if (i2 < s2) {
while (i2 < s2 && XDL_ISSPACE(l2[i2]))
i2++;
return (s2 == i2);
}
return 1;
}
static unsigned long xdl_hash_record_with_whitespace(char const **data,
char const *top, long flags) {
unsigned long ha = 5381;
char const *ptr = *data;
for (; ptr < top && *ptr != '\n'; ptr++) {
if (XDL_ISSPACE(*ptr)) {
const char *ptr2 = ptr;
int at_eol;
while (ptr + 1 < top && XDL_ISSPACE(ptr[1])
&& ptr[1] != '\n')
ptr++;
at_eol = (top <= ptr + 1 || ptr[1] == '\n');
if (flags & XDF_IGNORE_WHITESPACE)
; /* already handled */
else if (flags & XDF_IGNORE_WHITESPACE_CHANGE
&& !at_eol) {
ha += (ha << 5);
ha ^= (unsigned long) ' ';
}
else if (flags & XDF_IGNORE_WHITESPACE_AT_EOL
&& !at_eol) {
while (ptr2 != ptr + 1) {
ha += (ha << 5);
ha ^= (unsigned long) *ptr2;
ptr2++;
}
}
continue;
}
ha += (ha << 5);
ha ^= (unsigned long) *ptr;
}
*data = ptr < top ? ptr + 1: ptr;
return ha;
}
#ifdef XDL_FAST_HASH
#define REPEAT_BYTE(x) ((~0ul / 0xff) * (x))
#define ONEBYTES REPEAT_BYTE(0x01)
#define NEWLINEBYTES REPEAT_BYTE(0x0a)
#define HIGHBITS REPEAT_BYTE(0x80)
/* Return the high bit set in the first byte that is a zero */
static inline unsigned long has_zero(unsigned long a)
{
return ((a - ONEBYTES) & ~a) & HIGHBITS;
}
static inline long count_masked_bytes(unsigned long mask)
{
if (sizeof(long) == 8) {
/*
* Jan Achrenius on G+: microoptimized version of
* the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
* that works for the bytemasks without having to
* mask them first.
*/
/*
* return mask * 0x0001020304050608 >> 56;
*
* Doing it like this avoids warnings on 32-bit machines.
*/
long a = (REPEAT_BYTE(0x01) / 0xff + 1);
return mask * a >> (sizeof(long) * 7);
} else {
/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
/* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
long a = (0x0ff0001 + mask) >> 23;
/* Fix the 1 for 00 case */
return a & mask;
}
}
unsigned long xdl_hash_record(char const **data, char const *top, long flags)
{
unsigned long hash = 5381;
unsigned long a = 0, mask = 0;
char const *ptr = *data;
char const *end = top - sizeof(unsigned long) + 1;
if (flags & XDF_WHITESPACE_FLAGS)
return xdl_hash_record_with_whitespace(data, top, flags);
ptr -= sizeof(unsigned long);
do {
hash += hash << 5;
hash ^= a;
ptr += sizeof(unsigned long);
if (ptr >= end)
break;
a = *(unsigned long *)ptr;
/* Do we have any '\n' bytes in this word? */
mask = has_zero(a ^ NEWLINEBYTES);
} while (!mask);
if (ptr >= end) {
/*
* There is only a partial word left at the end of the
* buffer. Because we may work with a memory mapping,
* we have to grab the rest byte by byte instead of
* blindly reading it.
*
* To avoid problems with masking in a signed value,
* we use an unsigned char here.
*/
const char *p;
for (p = top - 1; p >= ptr; p--)
a = (a << 8) + *((const unsigned char *)p);
mask = has_zero(a ^ NEWLINEBYTES);
if (!mask)
/*
* No '\n' found in the partial word. Make a
* mask that matches what we read.
*/
mask = 1UL << (8 * (top - ptr) + 7);
}
/* The mask *below* the first high bit set */
mask = (mask - 1) & ~mask;
mask >>= 7;
hash += hash << 5;
hash ^= a & mask;
/* Advance past the last (possibly partial) word */
ptr += count_masked_bytes(mask);
if (ptr < top) {
assert(*ptr == '\n');
ptr++;
}
*data = ptr;
return hash;
}
#else /* XDL_FAST_HASH */
unsigned long xdl_hash_record(char const **data, char const *top, long flags) {
unsigned long ha = 5381;
char const *ptr = *data;
if (flags & XDF_WHITESPACE_FLAGS)
return xdl_hash_record_with_whitespace(data, top, flags);
for (; ptr < top && *ptr != '\n'; ptr++) {
ha += (ha << 5);
ha ^= (unsigned long) *ptr;
}
*data = ptr < top ? ptr + 1: ptr;
return ha;
}
#endif /* XDL_FAST_HASH */
unsigned int xdl_hashbits(unsigned int size) {
unsigned int val = 1, bits = 0;
for (; val < size && bits < CHAR_BIT * sizeof(unsigned int); val <<= 1, bits++);
return bits ? bits: 1;
}
int xdl_num_out(char *out, long val) {
char *ptr, *str = out;
char buf[32];
ptr = buf + sizeof(buf) - 1;
*ptr = '\0';
if (val < 0) {
*--ptr = '-';
val = -val;
}
for (; val && ptr > buf; val /= 10)
*--ptr = "0123456789"[val % 10];
if (*ptr)
for (; *ptr; ptr++, str++)
*str = *ptr;
else
*str++ = '0';
*str = '\0';
return str - out;
}
int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
const char *func, long funclen, xdemitcb_t *ecb) {
int nb = 0;
mmbuffer_t mb;
char buf[128];
memcpy(buf, "@@ -", 4);
nb += 4;
nb += xdl_num_out(buf + nb, c1 ? s1: s1 - 1);
if (c1 != 1) {
memcpy(buf + nb, ",", 1);
nb += 1;
nb += xdl_num_out(buf + nb, c1);
}
memcpy(buf + nb, " +", 2);
nb += 2;
nb += xdl_num_out(buf + nb, c2 ? s2: s2 - 1);
if (c2 != 1) {
memcpy(buf + nb, ",", 1);
nb += 1;
nb += xdl_num_out(buf + nb, c2);
}
memcpy(buf + nb, " @@", 3);
nb += 3;
if (func && funclen) {
buf[nb++] = ' ';
if (funclen > sizeof(buf) - nb - 1)
funclen = sizeof(buf) - nb - 1;
memcpy(buf + nb, func, funclen);
nb += funclen;
}
buf[nb++] = '\n';
mb.ptr = buf;
mb.size = nb;
if (ecb->outf(ecb->priv, &mb, 1) < 0)
return -1;
return 0;
}
int xdl_fall_back_diff(xdfenv_t *diff_env, xpparam_t const *xpp,
int line1, int count1, int line2, int count2)
{
/*
* This probably does not work outside Git, since
* we have a very simple mmfile structure.
*
* Note: ideally, we would reuse the prepared environment, but
* the libxdiff interface does not (yet) allow for diffing only
* ranges of lines instead of the whole files.
*/
mmfile_t subfile1, subfile2;
xdfenv_t env;
subfile1.ptr = (char *)diff_env->xdf1.recs[line1 - 1]->ptr;
subfile1.size = diff_env->xdf1.recs[line1 + count1 - 2]->ptr +
diff_env->xdf1.recs[line1 + count1 - 2]->size - subfile1.ptr;
subfile2.ptr = (char *)diff_env->xdf2.recs[line2 - 1]->ptr;
subfile2.size = diff_env->xdf2.recs[line2 + count2 - 2]->ptr +
diff_env->xdf2.recs[line2 + count2 - 2]->size - subfile2.ptr;
if (xdl_do_diff(&subfile1, &subfile2, xpp, &env) < 0)
return -1;
memcpy(diff_env->xdf1.rchg + line1 - 1, env.xdf1.rchg, count1);
memcpy(diff_env->xdf2.rchg + line2 - 1, env.xdf2.rchg, count2);
xdl_free_env(&env);
return 0;
}