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Add count{Leading,Trailing}Ones_{32,64} functions with simple implementations.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47084 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2008-02-13 20:54:54 +00:00
parent 02c4836f3d
commit ca2a0e1062
1 changed files with 32 additions and 0 deletions
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32
include/llvm/Support/MathExtras.h
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@@ -163,6 +163,14 @@ inline unsigned CountLeadingZeros_32(uint32_t Value) {
return Count; return Count;
} }
/// CountLeadingOnes_32 - this function performs the operation of
/// counting the number of ones from the most significant bit to the first zero
/// bit. Ex. CountLeadingOnes_32(0xFF0FFF00) == 8.
/// Returns 32 if the word is all ones.
inline unsigned CountLeadingOnes_32(uint32_t Value) {
return CountLeadingZeros_32(~Value);
}
/// CountLeadingZeros_64 - This function performs the platform optimal form /// CountLeadingZeros_64 - This function performs the platform optimal form
/// of counting the number of zeros from the most significant bit to the first /// of counting the number of zeros from the most significant bit to the first
/// one bit (64 bit edition.) /// one bit (64 bit edition.)
@@ -207,6 +215,14 @@ inline unsigned CountLeadingZeros_64(uint64_t Value) {
return Count; return Count;
} }
/// CountLeadingOnes_64 - This function performs the operation
/// of counting the number of ones from the most significant bit to the first
/// zero bit (64 bit edition.)
/// Returns 64 if the word is all ones.
inline unsigned CountLeadingOnes_64(uint64_t Value) {
return CountLeadingZeros_64(~Value);
}
/// CountTrailingZeros_32 - this function performs the platform optimal form of /// CountTrailingZeros_32 - this function performs the platform optimal form of
/// counting the number of zeros from the least significant bit to the first one /// counting the number of zeros from the least significant bit to the first one
/// bit. Ex. CountTrailingZeros_32(0xFF00FF00) == 8. /// bit. Ex. CountTrailingZeros_32(0xFF00FF00) == 8.
@@ -224,6 +240,14 @@ inline unsigned CountTrailingZeros_32(uint32_t Value) {
#endif #endif
} }
/// CountTrailingOnes_32 - this function performs the operation of
/// counting the number of ones from the least significant bit to the first zero
/// bit. Ex. CountTrailingOnes_32(0x00FF00FF) == 8.
/// Returns 32 if the word is all ones.
inline unsigned CountTrailingOnes_32(uint32_t Value) {
return CountTrailingZeros_32(~Value);
}
/// CountTrailingZeros_64 - This function performs the platform optimal form /// CountTrailingZeros_64 - This function performs the platform optimal form
/// of counting the number of zeros from the least significant bit to the first /// of counting the number of zeros from the least significant bit to the first
/// one bit (64 bit edition.) /// one bit (64 bit edition.)
@@ -243,6 +267,14 @@ inline unsigned CountTrailingZeros_64(uint64_t Value) {
#endif #endif
} }
/// CountTrailingOnes_64 - This function performs the operation
/// of counting the number of ones from the least significant bit to the first
/// zero bit (64 bit edition.)
/// Returns 64 if the word is all ones.
inline unsigned CountTrailingOnes_64(uint64_t Value) {
return CountTrailingZeros_64(~Value);
}
/// CountPopulation_32 - this function counts the number of set bits in a value. /// CountPopulation_32 - this function counts the number of set bits in a value.
/// Ex. CountPopulation(0xF000F000) = 8 /// Ex. CountPopulation(0xF000F000) = 8
/// Returns 0 if the word is zero. /// Returns 0 if the word is zero.