Author: djg Date: Wed Feb 13 14:54:54 2008 New Revision: 47084 URL: http://llvm.org/viewvc/llvm-project?rev=47084&view=rev Log: Add count{Leading,Trailing}Ones_{32,64} functions with simple implementations.
Modified: llvm/trunk/include/llvm/Support/MathExtras.h Modified: llvm/trunk/include/llvm/Support/MathExtras.h URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/MathExtras.h?rev=47084&r1=47083&r2=47084&view=diff ============================================================================== --- llvm/trunk/include/llvm/Support/MathExtras.h (original) +++ llvm/trunk/include/llvm/Support/MathExtras.h Wed Feb 13 14:54:54 2008 @@ -163,6 +163,14 @@ 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 /// of counting the number of zeros from the most significant bit to the first /// one bit (64 bit edition.) @@ -207,6 +215,14 @@ 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 /// counting the number of zeros from the least significant bit to the first one /// bit. Ex. CountTrailingZeros_32(0xFF00FF00) == 8. @@ -224,6 +240,14 @@ #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 /// of counting the number of zeros from the least significant bit to the first /// one bit (64 bit edition.) @@ -243,6 +267,14 @@ #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. /// Ex. CountPopulation(0xF000F000) = 8 /// Returns 0 if the word is zero. _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits