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livetrax/libs/appleutility/CoreAudio/PublicUtility/CABitOperations.h

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6.1 KiB
C

/*
File: CABitOperations.h
Abstract: Part of CoreAudio Utility Classes
Version: 1.1
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*/
#ifndef _CABitOperations_h_
#define _CABitOperations_h_
#if !defined(__COREAUDIO_USE_FLAT_INCLUDES__)
//#include <CoreServices/../Frameworks/CarbonCore.framework/Headers/MacTypes.h>
#include <CoreFoundation/CFBase.h>
#else
// #include <MacTypes.h>
#include "CFBase.h"
#endif
#include <TargetConditionals.h>
// 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