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patch-ids: use the new generic "sha1_pos" function to lookup sha1

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instead of the specific one from which the new one has been copied.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Christian Couder 2009-04-04 22:59:31 +02:00 committed by Junio C Hamano
parent 96beef8c2e
commit 5289bae17f
1 changed files with 5 additions and 88 deletions
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93
patch-ids.c
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@ -1,6 +1,7 @@
#include "cache.h"
#include "diff.h"
#include "commit.h"
#include "sha1-lookup.h"
#include "patch-ids.h"
static int commit_patch_id(struct commit *commit, struct diff_options *options,
@ -15,99 +16,15 @@ static int commit_patch_id(struct commit *commit, struct diff_options *options,
return diff_flush_patch_id(options, sha1);
}
static uint32_t take2(const unsigned char *id)
static const unsigned char *patch_id_access(size_t index, void *table)
{
return ((id[0] << 8) | id[1]);
struct patch_id **id_table = table;
return id_table[index]->patch_id;
}
/*
* Conventional binary search loop looks like this:
*
* do {
* int mi = (lo + hi) / 2;
* int cmp = "entry pointed at by mi" minus "target";
* if (!cmp)
* return (mi is the wanted one)
* if (cmp > 0)
* hi = mi; "mi is larger than target"
* else
* lo = mi+1; "mi is smaller than target"
* } while (lo < hi);
*
* The invariants are:
*
* - When entering the loop, lo points at a slot that is never
* above the target (it could be at the target), hi points at a
* slot that is guaranteed to be above the target (it can never
* be at the target).
*
* - We find a point 'mi' between lo and hi (mi could be the same
* as lo, but never can be the same as hi), and check if it hits
* the target. There are three cases:
*
* - if it is a hit, we are happy.
*
* - if it is strictly higher than the target, we update hi with
* it.
*
* - if it is strictly lower than the target, we update lo to be
* one slot after it, because we allow lo to be at the target.
*
* When choosing 'mi', we do not have to take the "middle" but
* anywhere in between lo and hi, as long as lo <= mi < hi is
* satisfied. When we somehow know that the distance between the
* target and lo is much shorter than the target and hi, we could
* pick mi that is much closer to lo than the midway.
*/
static int patch_pos(struct patch_id **table, int nr, const unsigned char *id)
{
int hi = nr;
int lo = 0;
int mi = 0;
if (!nr)
return -1;
if (nr != 1) {
unsigned lov, hiv, miv, ofs;
for (ofs = 0; ofs < 18; ofs += 2) {
lov = take2(table[0]->patch_id + ofs);
hiv = take2(table[nr-1]->patch_id + ofs);
miv = take2(id + ofs);
if (miv < lov)
return -1;
if (hiv < miv)
return -1 - nr;
if (lov != hiv) {
/*
* At this point miv could be equal
* to hiv (but id could still be higher);
* the invariant of (mi < hi) should be
* kept.
*/
mi = (nr-1) * (miv - lov) / (hiv - lov);
if (lo <= mi && mi < hi)
break;
die("oops");
}
}
if (18 <= ofs)
die("cannot happen -- lo and hi are identical");
}
do {
int cmp;
cmp = hashcmp(table[mi]->patch_id, id);
if (!cmp)
return mi;
if (cmp > 0)
hi = mi;
else
lo = mi + 1;
mi = (hi + lo) / 2;
} while (lo < hi);
return -lo-1;
return sha1_pos(id, table, nr, patch_id_access);
}
#define BUCKET_SIZE 190 /* 190 * 21 = 3990, with slop close enough to 4K */