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improve hash function (~33% less collisions)

This commit is contained in:
thrust26 2019-06-14 17:49:30 +02:00
parent c43db6d85c
commit 03280abf7f
2 changed files with 676 additions and 676 deletions
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14
src/common/KeyMap.hxx
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@ -102,13 +102,13 @@ class KeyMap
Mapping convertMod(const Mapping& mapping) const; Mapping convertMod(const Mapping& mapping) const;
struct KeyHash { struct KeyHash {
size_t operator()(const Mapping& m)const { size_t operator()(const Mapping& m) const {
return std::hash<uInt64>()((uInt64(m.mode)) // 1 bit return std::hash<uInt64>()((uInt64(m.mode)) // 3 bits
^ ((uInt64(m.key)) << 1) // 8 bits + ((uInt64(m.key)) * 7) // 8 bits
^ ((uInt64((m.mod & KBDM_SHIFT) != 0) << 9)) // 1 bit + (((uInt64((m.mod & KBDM_SHIFT) != 0) << 0)) // 1 bit
^ ((uInt64((m.mod & KBDM_ALT ) != 0) << 10)) // 1 bit | ((uInt64((m.mod & KBDM_ALT ) != 0) << 1)) // 1 bit
^ ((uInt64((m.mod & KBDM_GUI ) != 0) << 11)) // 1 bit | ((uInt64((m.mod & KBDM_GUI ) != 0) << 2)) // 1 bit
^ ((uInt64((m.mod & KBDM_CTRL ) != 0) << 12))); // 1 bit | ((uInt64((m.mod & KBDM_CTRL ) != 0) << 3))) * 2047); // 1 bit
} }
}; };