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All Rights Reserved. */ #ifndef _CABitOperations_h_ #define _CABitOperations_h_ #if !defined(__COREAUDIO_USE_FLAT_INCLUDES__) //#include #include #else // #include #include "CFBase.h" #endif #include // return whether a number is a power of two inline UInt32 IsPowerOfTwo(UInt32 x) { return (x & (x-1)) == 0; } // count the leading zeros in a word // Metrowerks Codewarrior. powerpc native count leading zeros instruction: // I think it's safe to remove this ... //#define CountLeadingZeroes(x) ((int)__cntlzw((unsigned int)x)) inline UInt32 CountLeadingZeroes(UInt32 arg) { // GNUC / LLVM have a builtin #if defined(__GNUC__) || defined(__llvm___) #if (TARGET_CPU_X86 || TARGET_CPU_X86_64) if (arg == 0) return 32; #endif // TARGET_CPU_X86 || TARGET_CPU_X86_64 return __builtin_clz(arg); #elif TARGET_OS_WIN32 UInt32 tmp; __asm{ bsr eax, arg mov ecx, 63 cmovz eax, ecx xor eax, 31 mov tmp, eax // this moves the result in tmp to return. } return tmp; #else #error "Unsupported architecture" #endif // defined(__GNUC__) } // Alias (with different spelling) #define CountLeadingZeros CountLeadingZeroes inline UInt32 CountLeadingZeroesLong(UInt64 arg) { // GNUC / LLVM have a builtin #if defined(__GNUC__) || defined(__llvm___) #if (TARGET_CPU_X86 || TARGET_CPU_X86_64) if (arg == 0) return 64; #endif // TARGET_CPU_X86 || TARGET_CPU_X86_64 return __builtin_clzll(arg); #elif TARGET_OS_WIN32 UInt32 x = CountLeadingZeroes((UInt32)(arg >> 32)); if(x < 32) return x; else return 32+CountLeadingZeroes((UInt32)arg); #else #error "Unsupported architecture" #endif // defined(__GNUC__) } #define CountLeadingZerosLong CountLeadingZeroesLong // count trailing zeroes inline UInt32 CountTrailingZeroes(UInt32 x) { return 32 - CountLeadingZeroes(~x & (x-1)); } // count leading ones inline UInt32 CountLeadingOnes(UInt32 x) { return CountLeadingZeroes(~x); } // count trailing ones inline UInt32 CountTrailingOnes(UInt32 x) { return 32 - CountLeadingZeroes(x & (~x-1)); } // number of bits required to represent x. inline UInt32 NumBits(UInt32 x) { return 32 - CountLeadingZeroes(x); } // base 2 log of next power of two greater or equal to x inline UInt32 Log2Ceil(UInt32 x) { return 32 - CountLeadingZeroes(x - 1); } // base 2 log of next power of two less or equal to x inline UInt32 Log2Floor(UInt32 x) { return 32 - CountLeadingZeroes(x) - 1; } // next power of two greater or equal to x inline UInt32 NextPowerOfTwo(UInt32 x) { return 1 << Log2Ceil(x); } // counting the one bits in a word inline UInt32 CountOnes(UInt32 x) { // secret magic algorithm for counting bits in a word. x = x - ((x >> 1) & 0x55555555); x = (x & 0x33333333) + ((x >> 2) & 0x33333333); return (((x + (x >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24; } // counting the zero bits in a word inline UInt32 CountZeroes(UInt32 x) { return CountOnes(~x); } // return the bit position (0..31) of the least significant bit inline UInt32 LSBitPos(UInt32 x) { return CountTrailingZeroes(x & -(SInt32)x); } // isolate the least significant bit inline UInt32 LSBit(UInt32 x) { return x & -(SInt32)x; } // return the bit position (0..31) of the most significant bit inline UInt32 MSBitPos(UInt32 x) { return 31 - CountLeadingZeroes(x); } // isolate the most significant bit inline UInt32 MSBit(UInt32 x) { return 1 << MSBitPos(x); } // Division optimized for power of 2 denominators inline UInt32 DivInt(UInt32 numerator, UInt32 denominator) { if(IsPowerOfTwo(denominator)) return numerator >> (31 - CountLeadingZeroes(denominator)); else return numerator/denominator; } #endif