From 998f1c960e004cd9223ce957f4e4f4485935b707 Mon Sep 17 00:00:00 2001 From: jvoisin Date: Fri, 20 May 2022 20:21:27 +0200 Subject: [PATCH] Improve the speed of toLower This significantly improves the speed of my fuzzer, by something like 15%. --- .../openmw_test_suite/misc/test_stringops.cpp | 4 ++-- components/misc/stringops.hpp | 23 +++++++++++++++++-- 2 files changed, 23 insertions(+), 4 deletions(-) diff --git a/apps/openmw_test_suite/misc/test_stringops.cpp b/apps/openmw_test_suite/misc/test_stringops.cpp index 7d8e93dc28..d21a74700c 100644 --- a/apps/openmw_test_suite/misc/test_stringops.cpp +++ b/apps/openmw_test_suite/misc/test_stringops.cpp @@ -93,8 +93,8 @@ namespace using RawValue = const char[4]; - constexpr RawValue foo = "foo"; - constexpr RawValue fooUpper = "FOO"; + constexpr RawValue foo = "f0#"; + constexpr RawValue fooUpper = "F0#"; constexpr RawValue bar = "bar"; template diff --git a/components/misc/stringops.hpp b/components/misc/stringops.hpp index fe4be00006..50bcf6a1d0 100644 --- a/components/misc/stringops.hpp +++ b/components/misc/stringops.hpp @@ -8,6 +8,25 @@ #include #include +/* Mapping table to go from uppercase to lowercase for plain ASCII.*/ +static constexpr unsigned char tolowermap[256] = { + 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, + 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, + 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, + 62, 63, 64, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, + 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 91, 92, 93, 94, 95, + 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, + 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, + 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, + 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, + 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, + 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, + 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, + 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, + 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, + 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255 +}; + namespace Misc { class StringUtils @@ -38,9 +57,9 @@ public: /// Plain and simple locale-unaware toLower. Anything from A to Z is lower-cased, multibyte characters are unchanged. /// Don't use std::tolower(char, locale&) because that is abysmally slow. /// Don't use tolower(int) because that depends on global locale. - static char toLower(char c) + static constexpr char toLower(char c) { - return (c >= 'A' && c <= 'Z') ? c + 'a' - 'A' : c; + return tolowermap[static_cast(c)]; } static bool ciLess(const std::string &x, const std::string &y) {