From b4e00f7306a160639f047b3421985e8f3d0c6fb1 Mon Sep 17 00:00:00 2001 From: Jonathan Tan Date: Tue, 13 Feb 2018 10:39:39 -0800 Subject: packfile: refactor hash search with fanout table Subsequent patches will introduce file formats that make use of a fanout array and a sorted table containing hashes, just like packfiles. Refactor the hash search in packfile.c into its own function, so that those patches can make use of it as well. Signed-off-by: Jonathan Tan Signed-off-by: Junio C Hamano --- sha1-lookup.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'sha1-lookup.c') diff --git a/sha1-lookup.c b/sha1-lookup.c index 4cf3ebd921..8d0b1db3e2 100644 --- a/sha1-lookup.c +++ b/sha1-lookup.c @@ -99,3 +99,31 @@ int sha1_pos(const unsigned char *sha1, void *table, size_t nr, } while (lo < hi); return -lo-1; } + +int bsearch_hash(const unsigned char *sha1, const uint32_t *fanout_nbo, + const unsigned char *table, size_t stride, uint32_t *result) +{ + uint32_t hi, lo; + + hi = ntohl(fanout_nbo[*sha1]); + lo = ((*sha1 == 0x0) ? 0 : ntohl(fanout_nbo[*sha1 - 1])); + + while (lo < hi) { + unsigned mi = lo + (hi - lo) / 2; + int cmp = hashcmp(table + mi * stride, sha1); + + if (!cmp) { + if (result) + *result = mi; + return 1; + } + if (cmp > 0) + hi = mi; + else + lo = mi + 1; + } + + if (result) + *result = lo; + return 0; +} -- cgit v1.3