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Math tzcnt

This commit is contained in:
Dr. Chat 2016-11-04 19:17:12 -05:00
parent e46a0c50fd
commit fe2c887c34
1 changed files with 50 additions and 4 deletions
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54
src/xenia/base/math.h
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@ -120,24 +120,70 @@ inline uint8_t lzcnt(uint64_t v) {
return static_cast<uint8_t>(is_nonzero ? int8_t(index) ^ 0x3F : 64);
}
#endif // LZCNT supported
inline uint8_t tzcnt(uint8_t v) {
unsigned long index;
unsigned long mask = v;
unsigned char is_nonzero = _BitScanForward(&index, mask);
return static_cast<uint8_t>(is_nonzero ? int8_t(index) ^ 0x7 : 8);
}
inline uint8_t tzcnt(uint16_t v) {
unsigned long index;
unsigned long mask = v;
unsigned char is_nonzero = _BitScanForward(&index, mask);
return static_cast<uint8_t>(is_nonzero ? int8_t(index) ^ 0xF : 16);
}
inline uint8_t tzcnt(uint32_t v) {
unsigned long index;
unsigned long mask = v;
unsigned char is_nonzero = _BitScanForward(&index, mask);
return static_cast<uint8_t>(is_nonzero ? int8_t(index) ^ 0x1F : 32);
}
inline uint8_t tzcnt(uint64_t v) {
unsigned long index;
unsigned long long mask = v;
unsigned char is_nonzero = _BitScanForward64(&index, mask);
return static_cast<uint8_t>(is_nonzero ? int8_t(index) ^ 0x3F : 64);
}
#else
inline uint8_t lzcnt(uint8_t v) {
return static_cast<uint8_t>(__builtin_clzs(v) - 8);
return v == 0 ? 8 : static_cast<uint8_t>(__builtin_clzs(v) - 8);
}
inline uint8_t lzcnt(uint16_t v) {
return static_cast<uint8_t>(__builtin_clzs(v));
return v == 0 ? 16 : static_cast<uint8_t>(__builtin_clzs(v));
}
inline uint8_t lzcnt(uint32_t v) {
return static_cast<uint8_t>(__builtin_clz(v));
return v == 0 ? 32 : static_cast<uint8_t>(__builtin_clz(v));
}
inline uint8_t lzcnt(uint64_t v) {
return static_cast<uint8_t>(__builtin_clzll(v));
return v == 0 ? 64 : static_cast<uint8_t>(__builtin_clzll(v));
}
inline uint8_t tzcnt(uint8_t v) {
return v == 0 ? 8 : static_cast<uint8_t>(__builtin_ctzs(v) - 8) ^ 0x7;
}
inline uint8_t tzcnt(uint16_t v) {
return v == 0 ? 16 : static_cast<uint8_t>(__builtin_ctzs(v)) ^ 0xF;
}
inline uint8_t tzcnt(uint32_t v) {
return v == 0 ? 32 : static_cast<uint8_t>(__builtin_ctz(v)) ^ 0x1F;
}
inline uint8_t tzcnt(uint64_t v) {
return v == 0 ? 64 : static_cast<uint8_t>(__builtin_ctzll(v)) ^ 0x3F;
}
#endif // XE_PLATFORM_WIN32
inline uint8_t lzcnt(int8_t v) { return lzcnt(static_cast<uint8_t>(v)); }
inline uint8_t lzcnt(int16_t v) { return lzcnt(static_cast<uint16_t>(v)); }
inline uint8_t lzcnt(int32_t v) { return lzcnt(static_cast<uint32_t>(v)); }
inline uint8_t lzcnt(int64_t v) { return lzcnt(static_cast<uint64_t>(v)); }
inline uint8_t tzcnt(int8_t v) { return tzcnt(static_cast<uint8_t>(v)); }
inline uint8_t tzcnt(int16_t v) { return tzcnt(static_cast<uint16_t>(v)); }
inline uint8_t tzcnt(int32_t v) { return tzcnt(static_cast<uint32_t>(v)); }
inline uint8_t tzcnt(int64_t v) { return tzcnt(static_cast<uint64_t>(v)); }
// BitScanForward (bsf).
// Search the value from least significant bit (LSB) to the most significant bit