sha1_name: parse less while finding common prefix

Create get_hex_char_from_oid() to parse oids one hex character at a
time. This prevents unnecessary copying of hex characters in
extend_abbrev_len() when finding the length of a common prefix.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Derrick Stolee 2017-10-12 08:02:19 -04:00 committed by Junio C Hamano
parent 5b20ace6a8
commit a42d6fd274

View File

@ -480,13 +480,23 @@ struct min_abbrev_data {
char *hex;
};
static inline char get_hex_char_from_oid(const struct object_id *oid,
unsigned int pos)
{
static const char hex[] = "0123456789abcdef";
if ((pos & 1) == 0)
return hex[oid->hash[pos >> 1] >> 4];
else
return hex[oid->hash[pos >> 1] & 0xf];
}
static int extend_abbrev_len(const struct object_id *oid, void *cb_data)
{
struct min_abbrev_data *mad = cb_data;
char *hex = oid_to_hex(oid);
unsigned int i = mad->init_len;
while (mad->hex[i] && mad->hex[i] == hex[i])
while (mad->hex[i] && mad->hex[i] == get_hex_char_from_oid(oid, i))
i++;
if (i < GIT_MAX_RAWSZ && i >= mad->cur_len)