misc.h

一个俄国人实现的数据库系统

#ifndef CRYPTOPP_MISC_H
#define CRYPTOPP_MISC_H

#include "config.h"
#include <assert.h>
#include <string.h>		// CodeWarrior doesn't have memory.h
#include <algorithm>
#include <string>

#ifdef INTEL_INTRINSICS
#include <stdlib.h>
#endif

NAMESPACE_BEGIN(CryptoPP)

// ************** misc functions ***************

#define GETBYTE(x, y) (unsigned int)(((x)>>(8*(y)))&255)
// this one may be faster on a Pentium
// #define GETBYTE(x, y) (((byte *)&(x))[y])

unsigned int Parity(unsigned long);
unsigned int BytePrecision(unsigned long);
unsigned int BitPrecision(unsigned long);
unsigned long Crop(unsigned long, unsigned int size);

inline unsigned int bitsToBytes(unsigned int bitCount)
{
	return ((bitCount+7)/(8));
}

inline unsigned int bytesToWords(unsigned int byteCount)
{
	return ((byteCount+WORD_SIZE-1)/WORD_SIZE);
}

inline unsigned int bitsToWords(unsigned int bitCount)
{
	return ((bitCount+WORD_BITS-1)/(WORD_BITS));
}

void xorbuf(byte *buf, const byte *mask, unsigned int count);
void xorbuf(byte *output, const byte *input, const byte *mask, unsigned int count);

inline unsigned int RoundDownToMultipleOf(unsigned int n, unsigned int m)
{
	return n - n%m;
}

inline unsigned int RoundUpToMultipleOf(unsigned int n, unsigned int m)
{
	return RoundDownToMultipleOf(n+m-1, m);
}

template <class T>
inline bool IsAligned(const void *p)
{
	return (unsigned int)p % sizeof(T) == 0;
}

inline bool CheckEndianess(bool highFirst)
{
#ifdef IS_LITTLE_ENDIAN
	return !highFirst;
#else
	return highFirst;
#endif
}

template <class T>		// can't use <sstream> because GCC 2.95.2 doesn't have it
std::string IntToString(T a)
{
	if (a == 0)
		return "0";
	bool negate = false;
	if (a < 0)
	{
		negate = true;
		a = -a;
	}
	std::string result;
	while (a > 0)
	{
		result = char('0' + a % 10) + result;
		a = a / 10;
	}
	if (negate)
		result = "-" + result;
	return result;
}

// ************** rotate functions ***************

template <class T> inline T rotlFixed(T x, unsigned int y)
{
	assert(y < sizeof(T)*8);
	return (x<<y) | (x>>(sizeof(T)*8-y));
}

template <class T> inline T rotrFixed(T x, unsigned int y)
{
	assert(y < sizeof(T)*8);
	return (x>>y) | (x<<(sizeof(T)*8-y));
}

template <class T> inline T rotlVariable(T x, unsigned int y)
{
	assert(y < sizeof(T)*8);
	return (x<<y) | (x>>(sizeof(T)*8-y));
}

template <class T> inline T rotrVariable(T x, unsigned int y)
{
	assert(y < sizeof(T)*8);
	return (x>>y) | (x<<(sizeof(T)*8-y));
}

template <class T> inline T rotlMod(T x, unsigned int y)
{
	y %= sizeof(T)*8;
	return (x<<y) | (x>>(sizeof(T)*8-y));
}

template <class T> inline T rotrMod(T x, unsigned int y)
{
	y %= sizeof(T)*8;
	return (x>>y) | (x<<(sizeof(T)*8-y));
}

#ifdef INTEL_INTRINSICS

template<> inline word32 rotlFixed<word32>(word32 x, unsigned int y)
{
	assert(y < 32);
	return y ? _lrotl(x, y) : x;
}

template<> inline word32 rotrFixed<word32>(word32 x, unsigned int y)
{
	assert(y < 32);
	return y ? _lrotr(x, y) : x;
}

template<> inline word32 rotlVariable<word32>(word32 x, unsigned int y)
{
	assert(y < 32);
	return _lrotl(x, y);
}

template<> inline word32 rotrVariable<word32>(word32 x, unsigned int y)
{
	assert(y < 32);
	return _lrotr(x, y);
}

template<> inline word32 rotlMod<word32>(word32 x, unsigned int y)
{
	return _lrotl(x, y);
}

template<> inline word32 rotrMod<word32>(word32 x, unsigned int y)
{
	return _lrotr(x, y);
}

#endif // #ifdef INTEL_INTRINSICS

#ifdef PPC_INTRINSICS

template<> inline word32 rotlFixed<word32>(word32 x, unsigned int y)
{
	assert(y < 32);
	return y ? __rlwinm(x,y,0,31) : x;
}

template<> inline word32 rotrFixed<word32>(word32 x, unsigned int y)
{
	assert(y < 32);
	return y ? __rlwinm(x,32-y,0,31) : x;
}

template<> inline word32 rotlVariable<word32>(word32 x, unsigned int y)
{
	assert(y < 32);
	return (__rlwnm(x,y,0,31));
}

template<> inline word32 rotrVariable<word32>(word32 x, unsigned int y)
{
	assert(y < 32);
	return (__rlwnm(x,32-y,0,31));
}

template<> inline word32 rotlMod<word32>(word32 x, unsigned int y)
{
	return (__rlwnm(x,y,0,31));
}

template<> inline word32 rotrMod<word32>(word32 x, unsigned int y)
{
	return (__rlwnm(x,32-y,0,31));
}

#endif // #ifdef PPC_INTRINSICS

// ************** endian reversal ***************

inline word16 byteReverse(word16 value)
{
	return rotlFixed(value, 8U);
}

inline word32 byteReverse(word32 value)
{
#ifdef PPC_INTRINSICS
	// PPC: load reverse indexed instruction
	return (word32)__lwbrx(&value,0);
#elif defined(FAST_ROTATE)
	// 5 instructions with rotate instruction, 9 without
	return (rotrFixed(value, 8U) & 0xff00ff00) | (rotlFixed(value, 8U) & 0x00ff00ff);
#else
	// 6 instructions with rotate instruction, 8 without
	value = ((value & 0xFF00FF00) >> 8) | ((value & 0x00FF00FF) << 8);
	return rotlFixed(value, 16U);
#endif
}

#ifdef WORD64_AVAILABLE
inline word64 byteReverse(word64 value)
{
#ifdef SLOW_WORD64
	return (word64(byteReverse(word32(value))) << 32) | byteReverse(word32(value>>32));
#else
	value = ((value & W64LIT(0xFF00FF00FF00FF00)) >> 8) | ((value & W64LIT(0x00FF00FF00FF00FF)) << 8);
	value = ((value & W64LIT(0xFFFF0000FFFF0000)) >> 16) | ((value & W64LIT(0x0000FFFF0000FFFF)) << 16);
	return rotlFixed(value, 32U);
#endif
}
#endif

inline byte bitReverse(byte value)
{
	value = ((value & 0xAA) >> 1) | ((value & 0x55) << 1);
	value = ((value & 0xCC) >> 2) | ((value & 0x33) << 2);
	return rotlFixed(value, 4);
}

inline word16 bitReverse(word16 value)
{
	value = ((value & 0xAAAA) >> 1) | ((value & 0x5555) << 1);
	value = ((value & 0xCCCC) >> 2) | ((value & 0x3333) << 2);
	value = ((value & 0xF0F0) >> 4) | ((value & 0x0F0F) << 4);
	return byteReverse(value);
}

inline word32 bitReverse(word32 value)
{
	value = ((value & 0xAAAAAAAA) >> 1) | ((value & 0x55555555) << 1);
	value = ((value & 0xCCCCCCCC) >> 2) | ((value & 0x33333333) << 2);
	value = ((value & 0xF0F0F0F0) >> 4) | ((value & 0x0F0F0F0F) << 4);
	return byteReverse(value);
}

#ifdef WORD64_AVAILABLE
inline word64 bitReverse(word64 value)
{
#ifdef SLOW_WORD64
	return (word64(bitReverse(word32(value))) << 32) | bitReverse(word32(value>>32));
#else
	value = ((value & W64LIT(0xAAAAAAAAAAAAAAAA)) >> 1) | ((value & W64LIT(0x5555555555555555)) << 1);
	value = ((value & W64LIT(0xCCCCCCCCCCCCCCCC)) >> 2) | ((value & W64LIT(0x3333333333333333)) << 2);
	value = ((value & W64LIT(0xF0F0F0F0F0F0F0F0)) >> 4) | ((value & W64LIT(0x0F0F0F0F0F0F0F0F)) << 4);
	return byteReverse(value);
#endif
}
#endif

template <class T>
inline T bitReverse(T value)
{
	if (sizeof(T) == 1)
		return bitReverse((byte)value);
	else if (sizeof(T) == 2)
		return bitReverse((word16)value);
	else if (sizeof(T) == 4)
		return bitReverse((word32)value);
	else
	{
#ifdef WORD64_AVAILABLE
		assert(sizeof(T) == 8);
		return bitReverse((word64)value);
#else
		assert(false);
		return 0;
#endif
	}
}

template <class T>
void byteReverse(T *out, const T *in, unsigned int byteCount)
{
	unsigned int count = (byteCount+sizeof(T)-1)/sizeof(T);
	for (unsigned int i=0; i<count; i++)
		out[i] = byteReverse(in[i]);
}

template <class T>
inline void GetUserKeyLittleEndian(T *out, unsigned int outlen, const byte *in, unsigned int inlen)
{
	const unsigned int U = sizeof(T);
	assert(inlen <= outlen*U);
	memcpy(out, in, inlen);
	memset((byte *)out+inlen, 0, outlen*U-inlen);
#ifndef IS_LITTLE_ENDIAN
	byteReverse(out, out, inlen);
#endif
}

template <class T>
inline void GetUserKeyBigEndian(T *out, unsigned int outlen, const byte *in, unsigned int inlen)
{
	const unsigned int U = sizeof(T);
	assert(inlen <= outlen*U);
	memcpy(out, in, inlen);
	memset((byte *)out+inlen, 0, outlen*U-inlen);
#ifdef IS_LITTLE_ENDIAN
	byteReverse(out, out, inlen);
#endif
}

// Fetch 2 words from user's buffer into "a", "b" in LITTLE-endian order
template <class T>
inline void GetBlockLittleEndian(const byte *block, T &a, T &b)
{
#ifdef IS_LITTLE_ENDIAN
	a = ((T *)block)[0];
	b = ((T *)block)[1];
#else
	a = byteReverse(((T *)block)[0]);
	b = byteReverse(((T *)block)[1]);
#endif
}

// Put 2 words back into user's buffer in LITTLE-endian order
template <class T>