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[PATCH] denser delta header encoding 

Since the delta data format is not tied to any actual git object
anymore, now is the time to add a small improvement to the delta data
header as it is been done for packed object header.  This patch allows
for reducing the delta header of about 2 bytes and makes for simpler
code.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Nicolas Pitre 2005-06-29 00:27:45 -04:00 committed by Linus Torvalds
parent 9d5ab9625d
commit 69a2d426f0
3 changed files with 37 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
count-delta.c
View File

@ -11,16 +11,13 @@
static unsigned long get_hdr_size(const unsigned char **datap)
{
const unsigned char *data = *datap;
unsigned long size;
unsigned char cmd;
int i;
size = i = 0;
cmd = *data++;
while (cmd) {
if (cmd & 1)
size |= *data++ << i;
i += 8;
cmd >>= 1;
unsigned char cmd = *data++;
unsigned long size = cmd & ~0x80;
int i = 7;
while (cmd & 0x80) {
cmd = *data++;
size |= (cmd & ~0x80) << i;
i += 7;
}
*datap = data;
return size;
@ -47,8 +44,8 @@ int count_delta(void *delta_buf, unsigned long delta_size,
unsigned char cmd;
unsigned long src_size, dst_size, out;
/* the smallest delta size possible is 6 bytes */
if (delta_size < 6)
/* the smallest delta size possible is 4 bytes */
if (delta_size < 4)
return -1;
data = delta_buf;

34
diff-delta.c
View File

@ -228,28 +228,22 @@ void *diff_delta(void *from_buf, unsigned long from_size,
top = to_buf + to_size;
/* store reference buffer size */
orig = out + outpos++;
*orig = i = 0;
do {
if (from_size & 0xff) {
*orig |= (1 << i);
out[outpos++] = from_size;
}
i++;
from_size >>= 8;
} while (from_size);
out[outpos++] = from_size;
from_size >>= 7;
while (from_size) {
out[outpos - 1] |= 0x80;
out[outpos++] = from_size;
from_size >>= 7;
}
/* store target buffer size */
orig = out + outpos++;
*orig = i = 0;
do {
if (to_size & 0xff) {
*orig |= (1 << i);
out[outpos++] = to_size;
}
i++;
to_size >>= 8;
} while (to_size);
out[outpos++] = to_size;
to_size >>= 7;
while (to_size) {
out[outpos - 1] |= 0x80;
out[outpos++] = to_size;
to_size >>= 7;
}
inscnt = 0;
moff = 0;

28
patch-delta.c
View File

@ -22,33 +22,33 @@ void *patch_delta(void *src_buf, unsigned long src_size,
unsigned long size;
int i;
/* the smallest delta size possible is 6 bytes */
if (delta_size < 6)
/* the smallest delta size possible is 4 bytes */
if (delta_size < 4)
return NULL;
data = delta_buf;
top = delta_buf + delta_size;
/* make sure the orig file size matches what we expect */
size = i = 0;
cmd = *data++;
while (cmd) {
if (cmd & 1)
size |= *data++ << i;
i += 8;
cmd >>= 1;
size = cmd & ~0x80;
i = 7;
while (cmd & 0x80) {
cmd = *data++;
size |= (cmd & ~0x80) << i;
i += 7;
}
if (size != src_size)
return NULL;
/* now the result size */
size = i = 0;
cmd = *data++;
while (cmd) {
if (cmd & 1)
size |= *data++ << i;
i += 8;
cmd >>= 1;
size = cmd & ~0x80;
i = 7;
while (cmd & 0x80) {
cmd = *data++;
size |= (cmd & ~0x80) << i;
i += 7;
}
dst_buf = malloc(size);
if (!dst_buf)