* The delta-parsing part is almost straight copy of patch-delta.c
* which is (C) 2005 Nicolas Pitre <nico@cam.org>.
*/
+#include "cache.h"
+#include "delta.h"
+#include "count-delta.h"
#include <stdlib.h>
#include <string.h>
#include <limits.h>
-#include "delta.h"
-#include "count-delta.h"
+
+struct span {
+ struct span *next;
+ unsigned long ofs;
+ unsigned long end;
+};
+
+static void touch_range(struct span **span,
+ unsigned long ofs, unsigned long end)
+{
+ struct span *e = *span;
+ struct span *p = NULL;
+
+ while (e && e->ofs <= ofs) {
+ again:
+ if (ofs < e->end) {
+ while (e->end < end) {
+ if (e->next) {
+ e->end = e->next->ofs;
+ e = e->next;
+ }
+ else {
+ e->end = end;
+ return;
+ }
+ }
+ return;
+ }
+ p = e;
+ e = e->next;
+ }
+ if (e && e->ofs <= end) {
+ e->ofs = ofs;
+ goto again;
+ }
+ else {
+ e = xmalloc(sizeof(*e));
+ e->ofs = ofs;
+ e->end = end;
+ if (p) {
+ e->next = p->next;
+ p->next = e;
+ }
+ else {
+ e->next = *span;
+ *span = e;
+ }
+ }
+}
+
+static unsigned long count_range(struct span *s)
+{
+ struct span *t;
+ unsigned long sz = 0;
+ while (s) {
+ t = s;
+ sz += s->end - s->ofs;
+ s = s->next;
+ free(t);
+ }
+ return sz;
+}
/*
* NOTE. We do not _interpret_ delta fully. As an approximation, we
int count_delta(void *delta_buf, unsigned long delta_size,
unsigned long *src_copied, unsigned long *literal_added)
{
- unsigned long copied_from_source, added_literal;
+ unsigned long added_literal;
const unsigned char *data, *top;
unsigned char cmd;
unsigned long src_size, dst_size, out;
+ struct span *span = NULL;
if (delta_size < DELTA_SIZE_MIN)
return -1;
src_size = get_delta_hdr_size(&data);
dst_size = get_delta_hdr_size(&data);
- added_literal = copied_from_source = out = 0;
+ added_literal = out = 0;
while (data < top) {
cmd = *data++;
if (cmd & 0x80) {
if (cmd & 0x40) cp_size |= (*data++ << 16);
if (cp_size == 0) cp_size = 0x10000;
- copied_from_source += cp_size;
+ touch_range(&span, cp_off, cp_off+cp_size);
out += cp_size;
} else {
/* write literal into dst */
}
}
+ *src_copied = count_range(span);
+
/* sanity check */
if (data != top || out != dst_size)
return -1;
/* delete size is what was _not_ copied from source.
* edit size is that and literal additions.
*/
- *src_copied = copied_from_source;
*literal_added = added_literal;
return 0;
}
#include <stdlib.h>
#include <string.h>
-#include <zlib.h>
#include "delta.h"
-/* block size: min = 16, max = 64k, power of 2 */
-#define BLK_SIZE 16
-
-#define MIN(a, b) ((a) < (b) ? (a) : (b))
-
-#define GR_PRIME 0x9e370001
-#define HASH(v, shift) (((unsigned int)(v) * GR_PRIME) >> (shift))
-
struct index {
const unsigned char *ptr;
- unsigned int val;
struct index *next;
};
unsigned long bufsize,
unsigned int *hash_shift)
{
- unsigned int hsize, hshift, entries, blksize, i;
+ unsigned long hsize;
+ unsigned int hshift, i;
const unsigned char *data;
struct index *entry, **hash;
void *mem;
/* determine index hash size */
- entries = (bufsize + BLK_SIZE - 1) / BLK_SIZE;
- hsize = entries / 4;
- for (i = 4; (1 << i) < hsize && i < 16; i++);
+ hsize = bufsize / 4;
+ for (i = 8; (1 << i) < hsize && i < 16; i++);
hsize = 1 << i;
- hshift = 32 - i;
+ hshift = i - 8;
*hash_shift = hshift;
/* allocate lookup index */
- mem = malloc(hsize * sizeof(*hash) + entries * sizeof(*entry));
+ mem = malloc(hsize * sizeof(*hash) + bufsize * sizeof(*entry));
if (!mem)
return NULL;
hash = mem;
memset(hash, 0, hsize * sizeof(*hash));
/* then populate it */
- data = buf + entries * BLK_SIZE - BLK_SIZE;
- blksize = bufsize - (data - buf);
- while (data >= buf) {
- unsigned int val = adler32(0, data, blksize);
- i = HASH(val, hshift);
- entry->ptr = data;
- entry->val = val;
+ data = buf + bufsize - 2;
+ while (data > buf) {
+ entry->ptr = --data;
+ i = data[0] ^ data[1] ^ (data[2] << hshift);
entry->next = hash[i];
hash[i] = entry++;
- blksize = BLK_SIZE;
- data -= BLK_SIZE;
}
return hash;
while (data < top) {
unsigned int moff = 0, msize = 0;
- unsigned int blksize = MIN(top - data, BLK_SIZE);
- unsigned int val = adler32(0, data, blksize);
- i = HASH(val, hash_shift);
- for (entry = hash[i]; entry; entry = entry->next) {
- const unsigned char *ref = entry->ptr;
- const unsigned char *src = data;
- unsigned int ref_size = ref_top - ref;
- if (entry->val != val)
- continue;
- if (ref_size > top - src)
- ref_size = top - src;
- while (ref_size && *src++ == *ref) {
- ref++;
- ref_size--;
- }
- ref_size = ref - entry->ptr;
- if (ref_size > msize) {
- /* this is our best match so far */
- moff = entry->ptr - ref_data;
- msize = ref_size;
- if (msize >= 0x10000) {
- msize = 0x10000;
+ if (data + 2 < top) {
+ i = data[0] ^ data[1] ^ (data[2] << hash_shift);
+ for (entry = hash[i]; entry; entry = entry->next) {
+ const unsigned char *ref = entry->ptr;
+ const unsigned char *src = data;
+ unsigned int ref_size = ref_top - ref;
+ if (ref_size > top - src)
+ ref_size = top - src;
+ if (ref_size > 0x10000)
+ ref_size = 0x10000;
+ if (ref_size <= msize)
break;
+ while (ref_size && *src++ == *ref) {
+ ref++;
+ ref_size--;
+ }
+ ref_size = ref - entry->ptr;
+ if (msize < ref - entry->ptr) {
+ /* this is our best match so far */
+ msize = ref - entry->ptr;
+ moff = entry->ptr - ref_data;
}
}
}
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