diff options
| -rw-r--r-- | libbb/appletlib.c | 80 |
1 files changed, 77 insertions, 3 deletions
diff --git a/libbb/appletlib.c b/libbb/appletlib.c index aeaf238f1..18583f91a 100644 --- a/libbb/appletlib.c +++ b/libbb/appletlib.c @@ -141,10 +141,28 @@ void FAST_FUNC bb_show_usage(void) int FAST_FUNC find_applet_by_name(const char *name) { - unsigned i, max; - int j; + unsigned i, j, max; const char *p; +/* The commented-out word-at-a-time code is ~40% faster, but +160 bytes. + * "Faster" here saves ~0.5 microsecond of real time - not worth it. + */ +#if 0 /*BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN*/ + uint32_t n32; + + /* Handle all names < 2 chars long early */ + if (name[0] == '\0') + return -1; /* "" is not a valid applet name */ + if (name[1] == '\0') { + if (!ENABLE_TEST) + return -1; /* 1-char name is not valid */ + if (name[0] != ']') + return -1; /* 1-char name which isn't "[" is not valid */ + /* applet "[" is always applet #0: */ + return 0; + } +#endif + p = applet_names; i = 0; #if KNOWN_APPNAME_OFFSETS <= 0 @@ -166,7 +184,62 @@ int FAST_FUNC find_applet_by_name(const char *name) //bb_error_msg("name:'%s' starting from:'%s' i:%u max:%u", name, p, i, max); #endif - /* Open-coding without strcmp/strlen calls for speed */ + /* Open-coded linear seatch without strcmp/strlen calls for speed */ + +#if 0 /*BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN*/ + /* skip "[\0" name, it's surely not it */ + if (ENABLE_TEST && LONE_CHAR(p, '[')) + i++, p += 2; + /* All remaining applet names in p[] are at least 2 chars long */ + /* name[] is also at least 2 chars long */ + + n32 = (name[0] << 0) | (name[1] << 8) | (name[2] << 16); + while (i < max) { + uint32_t p32; + char ch; + + /* Quickly check match of the first 3 bytes */ + move_from_unaligned32(p32, p); + p += 3; + if ((p32 & 0x00ffffff) != n32) { + /* Most likely case: 3 first bytes do not match */ + i++; + if ((p32 & 0x00ff0000) == '\0') + continue; // p[2] was NUL + p++; + if ((p32 & 0xff000000) == '\0') + continue; // p[3] was NUL + /* p[0..3] aren't matching and none is NUL, check the rest */ + while (*p++ != '\0') + continue; + continue; + } + + /* Unlikely branch: first 3 bytes ([0..2]) match */ + if ((p32 & 0x00ff0000) == '\0') { + /* name is 2-byte long, it is full match */ + //bb_error_msg("found:'%s' i:%u", name, i); + return i; + } + /* Check remaining bytes [3..NUL] */ + ch = (p32 >> 24); + j = 3; + while (ch == name[j]) { + if (ch == '\0') { + //bb_error_msg("found:'%s' i:%u", name, i); + return i; + } + ch = *++p; + j++; + } + /* Not a match. Skip it, including NUL */ + while (ch != '\0') + ch = *++p; + p++; + i++; + } + return -1; +#else while (i < max) { char ch; j = 0; @@ -189,6 +262,7 @@ int FAST_FUNC find_applet_by_name(const char *name) i++; } return -1; +#endif } |