diff options
| author | Alin Mr <almr.oss@outlook.com> | 2021-07-28 11:40:01 +0300 |
|---|---|---|
| committer | Denys Vlasenko <vda.linux@googlemail.com> | 2021-10-09 02:15:52 +0200 |
| commit | 21e8dbfd9d11a461ed7f91b495fa39d8a9131b28 (patch) | |
| tree | f7e2a43aa315aed066f13e2e09f5b52cdb0b5985 /shell | |
| parent | 94eb1c4dc6556932e1a12a0ce7734512ac95985e (diff) | |
| download | busybox-21e8dbfd9d11a461ed7f91b495fa39d8a9131b28.tar.gz | |
ash.c: speedup ${s:} substring (no quotes)
This trivial patch makes ${s:...} at least as fast as ${s#??..}
in simple tests. It's probably faster for longer substrings,
but then one wouldn't use ${s#"1024???s"} anyway -
one would switch away from sh.
function old new delta
subevalvar 1457 1503 +46
Signed-off-by: Alin Mr <almr.oss@outlook.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'shell')
| -rw-r--r-- | shell/ash.c | 17 |
1 files changed, 11 insertions, 6 deletions
diff --git a/shell/ash.c b/shell/ash.c index 7b85981ec..e8ec0b1a6 100644 --- a/shell/ash.c +++ b/shell/ash.c @@ -7185,14 +7185,19 @@ subevalvar(char *start, char *str, int strloc, if ((unsigned)len > (orig_len - pos)) len = orig_len - pos; - for (vstr = startp; pos; vstr++, pos--) { - if (quotes && (unsigned char)*vstr == CTLESC) + if (!quotes) { + loc = mempcpy(startp, startp + pos, len); + } else { + for (vstr = startp; pos != 0; pos--) { + if ((unsigned char)*vstr == CTLESC) + vstr++; vstr++; - } - for (loc = startp; len; len--) { - if (quotes && (unsigned char)*vstr == CTLESC) + } + for (loc = startp; len != 0; len--) { + if ((unsigned char)*vstr == CTLESC) + *loc++ = *vstr++; *loc++ = *vstr++; - *loc++ = *vstr++; + } } *loc = '\0'; goto out; |