src/common/tuklib_integer.h - jrn/xz - Git at Google

 ///////////////////////////////////////////////////////////////////////////////
 //
 /// \file       tuklib_integer.h
 /// \brief      Various integer and bit operations
 ///
 /// This file provides macros or functions to do some basic integer and bit
 /// operations.
 ///
 /// Endianness related integer operations (XX = 16, 32, or 64; Y = b or l):
 ///   - Byte swapping: bswapXX(num)
 ///   - Byte order conversions to/from native: convXXYe(num)
 ///   - Aligned reads: readXXYe(ptr)
 ///   - Aligned writes: writeXXYe(ptr, num)
 ///   - Unaligned reads (16/32-bit only): unaligned_readXXYe(ptr)
 ///   - Unaligned writes (16/32-bit only): unaligned_writeXXYe(ptr, num)
 ///
 /// Since they can macros, the arguments should have no side effects since
 /// they may be evaluated more than once.
 ///
 /// \todo       PowerPC and possibly some other architectures support
 ///             byte swapping load and store instructions. This file
 ///             doesn't take advantage of those instructions.
 ///
 /// Bit scan operations for non-zero 32-bit integers:
 ///   - Bit scan reverse (find highest non-zero bit): bsr32(num)
 ///   - Count leading zeros: clz32(num)
 ///   - Count trailing zeros: ctz32(num)
 ///   - Bit scan forward (simply an alias for ctz32()): bsf32(num)
 ///
 /// The above bit scan operations return 0-31. If num is zero,
 /// the result is undefined.
 //
 //  Authors:    Lasse Collin
 //              Joachim Henke
 //
 //  This file has been put into the public domain.
 //  You can do whatever you want with this file.
 //
 ///////////////////////////////////////////////////////////////////////////////

 #ifndef TUKLIB_INTEGER_H
 #define TUKLIB_INTEGER_H

 #include "tuklib_common.h"


 ////////////////////////////////////////
 // Operating system specific features //
 ////////////////////////////////////////

 #if defined(HAVE_BYTESWAP_H)
 	// glibc, uClibc, dietlibc
 #	include <byteswap.h>
 #	ifdef HAVE_BSWAP_16
 #		define bswap16(num) bswap_16(num)
 #	endif
 #	ifdef HAVE_BSWAP_32
 #		define bswap32(num) bswap_32(num)
 #	endif
 #	ifdef HAVE_BSWAP_64
 #		define bswap64(num) bswap_64(num)
 #	endif

 #elif defined(HAVE_SYS_ENDIAN_H)
 	// *BSDs and Darwin
 #	include <sys/endian.h>

 #elif defined(HAVE_SYS_BYTEORDER_H)
 	// Solaris
 #	include <sys/byteorder.h>
 #	ifdef BSWAP_16
 #		define bswap16(num) BSWAP_16(num)
 #	endif
 #	ifdef BSWAP_32
 #		define bswap32(num) BSWAP_32(num)
 #	endif
 #	ifdef BSWAP_64
 #		define bswap64(num) BSWAP_64(num)
 #	endif
 #	ifdef BE_16
 #		define conv16be(num) BE_16(num)
 #	endif
 #	ifdef BE_32
 #		define conv32be(num) BE_32(num)
 #	endif
 #	ifdef BE_64
 #		define conv64be(num) BE_64(num)
 #	endif
 #	ifdef LE_16
 #		define conv16le(num) LE_16(num)
 #	endif
 #	ifdef LE_32
 #		define conv32le(num) LE_32(num)
 #	endif
 #	ifdef LE_64
 #		define conv64le(num) LE_64(num)
 #	endif
 #endif


 ///////////////////
 // Byte swapping //
 ///////////////////

 #ifndef bswap16
 #	define bswap16(num) \
 		(((uint16_t)(num) << 8) | ((uint16_t)(num) >> 8))
 #endif

 #ifndef bswap32
 #	define bswap32(num) \
 		( (((uint32_t)(num) << 24)                       ) \
 		| (((uint32_t)(num) <<  8) & UINT32_C(0x00FF0000)) \
 		| (((uint32_t)(num) >>  8) & UINT32_C(0x0000FF00)) \
 		| (((uint32_t)(num) >> 24)                       ) )
 #endif

 #ifndef bswap64
 #	define bswap64(num) \
 		( (((uint64_t)(num) << 56)                               ) \
 		| (((uint64_t)(num) << 40) & UINT64_C(0x00FF000000000000)) \
 		| (((uint64_t)(num) << 24) & UINT64_C(0x0000FF0000000000)) \
 		| (((uint64_t)(num) <<  8) & UINT64_C(0x000000FF00000000)) \
 		| (((uint64_t)(num) >>  8) & UINT64_C(0x00000000FF000000)) \
 		| (((uint64_t)(num) >> 24) & UINT64_C(0x0000000000FF0000)) \
 		| (((uint64_t)(num) >> 40) & UINT64_C(0x000000000000FF00)) \
 		| (((uint64_t)(num) >> 56)                               ) )
 #endif

 // Define conversion macros using the basic byte swapping macros.
 #ifdef WORDS_BIGENDIAN
 #	ifndef conv16be
 #		define conv16be(num) ((uint16_t)(num))
 #	endif
 #	ifndef conv32be
 #		define conv32be(num) ((uint32_t)(num))
 #	endif
 #	ifndef conv64be
 #		define conv64be(num) ((uint64_t)(num))
 #	endif
 #	ifndef conv16le
 #		define conv16le(num) bswap16(num)
 #	endif
 #	ifndef conv32le
 #		define conv32le(num) bswap32(num)
 #	endif
 #	ifndef conv64le
 #		define conv64le(num) bswap64(num)
 #	endif
 #else
 #	ifndef conv16be
 #		define conv16be(num) bswap16(num)
 #	endif
 #	ifndef conv32be
 #		define conv32be(num) bswap32(num)
 #	endif
 #	ifndef conv64be
 #		define conv64be(num) bswap64(num)
 #	endif
 #	ifndef conv16le
 #		define conv16le(num) ((uint16_t)(num))
 #	endif
 #	ifndef conv32le
 #		define conv32le(num) ((uint32_t)(num))
 #	endif
 #	ifndef conv64le
 #		define conv64le(num) ((uint64_t)(num))
 #	endif
 #endif


 //////////////////////////////
 // Aligned reads and writes //
 //////////////////////////////

 static inline uint16_t
 read16be(const uint8_t *buf)
 {
 	uint16_t num = *(const uint16_t *)buf;
 	return conv16be(num);
 }


 static inline uint16_t
 read16le(const uint8_t *buf)
 {
 	uint16_t num = *(const uint16_t *)buf;
 	return conv16le(num);
 }


 static inline uint32_t
 read32be(const uint8_t *buf)
 {
 	uint32_t num = *(const uint32_t *)buf;
 	return conv32be(num);
 }


 static inline uint32_t
 read32le(const uint8_t *buf)
 {
 	uint32_t num = *(const uint32_t *)buf;
 	return conv32le(num);
 }


 static inline uint64_t
 read64be(const uint8_t *buf)
 {
 	uint64_t num = *(const uint64_t *)buf;
 	return conv64be(num);
 }


 static inline uint64_t
 read64le(const uint8_t *buf)
 {
 	uint64_t num = *(const uint64_t *)buf;
 	return conv64le(num);
 }


 // NOTE: Possible byte swapping must be done in a macro to allow GCC
 // to optimize byte swapping of constants when using glibc's or *BSD's
 // byte swapping macros. The actual write is done in an inline function
 // to make type checking of the buf pointer possible similarly to readXXYe()
 // functions.

 #define write16be(buf, num) write16ne((buf), conv16be(num))
 #define write16le(buf, num) write16ne((buf), conv16le(num))
 #define write32be(buf, num) write32ne((buf), conv32be(num))
 #define write32le(buf, num) write32ne((buf), conv32le(num))
 #define write64be(buf, num) write64ne((buf), conv64be(num))
 #define write64le(buf, num) write64ne((buf), conv64le(num))


 static inline void
 write16ne(uint8_t *buf, uint16_t num)
 {
 	*(uint16_t *)buf = num;
 	return;
 }


 static inline void
 write32ne(uint8_t *buf, uint32_t num)
 {
 	*(uint32_t *)buf = num;
 	return;
 }


 static inline void
 write64ne(uint8_t *buf, uint64_t num)
 {
 	*(uint64_t *)buf = num;
 	return;
 }


 ////////////////////////////////
 // Unaligned reads and writes //
 ////////////////////////////////

 // NOTE: TUKLIB_FAST_UNALIGNED_ACCESS indicates only support for 16-bit and
 // 32-bit unaligned integer loads and stores. It's possible that 64-bit
 // unaligned access doesn't work or is slower than byte-by-byte access.
 // Since unaligned 64-bit is probably not needed as often as 16-bit or
 // 32-bit, we simply don't support 64-bit unaligned access for now.
 #ifdef TUKLIB_FAST_UNALIGNED_ACCESS
 #	define unaligned_read16be read16be
 #	define unaligned_read16le read16le
 #	define unaligned_read32be read32be
 #	define unaligned_read32le read32le
 #	define unaligned_write16be write16be
 #	define unaligned_write16le write16le
 #	define unaligned_write32be write32be
 #	define unaligned_write32le write32le

 #else

 static inline uint16_t
 unaligned_read16be(const uint8_t *buf)
 {
 	uint16_t num = ((uint16_t)buf[0] << 8) | (uint16_t)buf[1];
 	return num;
 }


 static inline uint16_t
 unaligned_read16le(const uint8_t *buf)
 {
 	uint16_t num = ((uint16_t)buf[0]) | ((uint16_t)buf[1] << 8);
 	return num;
 }


 static inline uint32_t
 unaligned_read32be(const uint8_t *buf)
 {
 	uint32_t num = (uint32_t)buf[0] << 24;
 	num |= (uint32_t)buf[1] << 16;
 	num |= (uint32_t)buf[2] << 8;
 	num |= (uint32_t)buf[3];
 	return num;
 }


 static inline uint32_t
 unaligned_read32le(const uint8_t *buf)
 {
 	uint32_t num = (uint32_t)buf[0];
 	num |= (uint32_t)buf[1] << 8;
 	num |= (uint32_t)buf[2] << 16;
 	num |= (uint32_t)buf[3] << 24;
 	return num;
 }


 static inline void
 unaligned_write16be(uint8_t *buf, uint16_t num)
 {
 	buf[0] = num >> 8;
 	buf[1] = num;
 	return;
 }


 static inline void
 unaligned_write16le(uint8_t *buf, uint16_t num)
 {
 	buf[0] = num;
 	buf[1] = num >> 8;
 	return;
 }


 static inline void
 unaligned_write32be(uint8_t *buf, uint32_t num)
 {
 	buf[0] = num >> 24;
 	buf[1] = num >> 16;
 	buf[2] = num >> 8;
 	buf[3] = num;
 	return;
 }


 static inline void
 unaligned_write32le(uint8_t *buf, uint32_t num)
 {
 	buf[0] = num;
 	buf[1] = num >> 8;
 	buf[2] = num >> 16;
 	buf[3] = num >> 24;
 	return;
 }

 #endif


 static inline uint32_t
 bsr32(uint32_t n)
 {
 	// Check for ICC first, since it tends to define __GNUC__ too.
 #if defined(__INTEL_COMPILER)
 	return _bit_scan_reverse(n);

 #elif TUKLIB_GNUC_REQ(3, 4) && UINT_MAX == UINT32_MAX
 	// GCC >= 3.4 has __builtin_clz(), which gives good results on
 	// multiple architectures. On x86, __builtin_clz() ^ 31U becomes
 	// either plain BSR (so the XOR gets optimized away) or LZCNT and
 	// XOR (if -march indicates that SSE4a instructions are supported).
 	return __builtin_clz(n) ^ 31U;

 #elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
 	uint32_t i;
 	__asm__("bsrl %1, %0" : "=r" (i) : "rm" (n));
 	return i;

 #elif defined(_MSC_VER) && _MSC_VER >= 1400
 	// MSVC isn't supported by tuklib, but since this code exists,
 	// it doesn't hurt to have it here anyway.
 	uint32_t i;
 	_BitScanReverse((DWORD *)&i, n);
 	return i;

 #else
 	uint32_t i = 31;

 	if ((n & UINT32_C(0xFFFF0000)) == 0) {
 		n <<= 16;
 		i = 15;
 	}

 	if ((n & UINT32_C(0xFF000000)) == 0) {
 		n <<= 8;
 		i -= 8;
 	}

 	if ((n & UINT32_C(0xF0000000)) == 0) {
 		n <<= 4;
 		i -= 4;
 	}

 	if ((n & UINT32_C(0xC0000000)) == 0) {
 		n <<= 2;
 		i -= 2;
 	}

 	if ((n & UINT32_C(0x80000000)) == 0)
 		--i;

 	return i;
 #endif
 }


 static inline uint32_t
 clz32(uint32_t n)
 {
 #if defined(__INTEL_COMPILER)
 	return _bit_scan_reverse(n) ^ 31U;

 #elif TUKLIB_GNUC_REQ(3, 4) && UINT_MAX == UINT32_MAX
 	return __builtin_clz(n);

 #elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
 	uint32_t i;
 	__asm__("bsrl %1, %0\n\t"
 		"xorl $31, %0"
 		: "=r" (i) : "rm" (n));
 	return i;

 #elif defined(_MSC_VER) && _MSC_VER >= 1400
 	uint32_t i;
 	_BitScanReverse((DWORD *)&i, n);
 	return i ^ 31U;

 #else
 	uint32_t i = 0;

 	if ((n & UINT32_C(0xFFFF0000)) == 0) {
 		n <<= 16;
 		i = 16;
 	}

 	if ((n & UINT32_C(0xFF000000)) == 0) {
 		n <<= 8;
 		i += 8;
 	}

 	if ((n & UINT32_C(0xF0000000)) == 0) {
 		n <<= 4;
 		i += 4;
 	}

 	if ((n & UINT32_C(0xC0000000)) == 0) {
 		n <<= 2;
 		i += 2;
 	}

 	if ((n & UINT32_C(0x80000000)) == 0)
 		++i;

 	return i;
 #endif
 }


 static inline uint32_t
 ctz32(uint32_t n)
 {
 #if defined(__INTEL_COMPILER)
 	return _bit_scan_forward(n);

 #elif TUKLIB_GNUC_REQ(3, 4) && UINT_MAX >= UINT32_MAX
 	return __builtin_ctz(n);

 #elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
 	uint32_t i;
 	__asm__("bsfl %1, %0" : "=r" (i) : "rm" (n));
 	return i;

 #elif defined(_MSC_VER) && _MSC_VER >= 1400
 	uint32_t i;
 	_BitScanForward((DWORD *)&i, n);
 	return i;

 #else
 	uint32_t i = 0;

 	if ((n & UINT32_C(0x0000FFFF)) == 0) {
 		n >>= 16;
 		i = 16;
 	}

 	if ((n & UINT32_C(0x000000FF)) == 0) {
 		n >>= 8;
 		i += 8;
 	}

 	if ((n & UINT32_C(0x0000000F)) == 0) {
 		n >>= 4;
 		i += 4;
 	}

 	if ((n & UINT32_C(0x00000003)) == 0) {
 		n >>= 2;
 		i += 2;
 	}

 	if ((n & UINT32_C(0x00000001)) == 0)
 		++i;

 	return i;
 #endif
 }

 #define bsf32 ctz32

 #endif
	///////////////////////////////////////////////////////////////////////////////
	//
	/// \file tuklib_integer.h
	/// \brief Various integer and bit operations
	///
	/// This file provides macros or functions to do some basic integer and bit
	/// operations.
	///
	/// Endianness related integer operations (XX = 16, 32, or 64; Y = b or l):
	/// - Byte swapping: bswapXX(num)
	/// - Byte order conversions to/from native: convXXYe(num)
	/// - Aligned reads: readXXYe(ptr)
	/// - Aligned writes: writeXXYe(ptr, num)
	/// - Unaligned reads (16/32-bit only): unaligned_readXXYe(ptr)
	/// - Unaligned writes (16/32-bit only): unaligned_writeXXYe(ptr, num)
	///
	/// Since they can macros, the arguments should have no side effects since
	/// they may be evaluated more than once.
	///
	/// \todo PowerPC and possibly some other architectures support
	/// byte swapping load and store instructions. This file
	/// doesn't take advantage of those instructions.
	///
	/// Bit scan operations for non-zero 32-bit integers:
	/// - Bit scan reverse (find highest non-zero bit): bsr32(num)
	/// - Count leading zeros: clz32(num)
	/// - Count trailing zeros: ctz32(num)
	/// - Bit scan forward (simply an alias for ctz32()): bsf32(num)
	///
	/// The above bit scan operations return 0-31. If num is zero,
	/// the result is undefined.
	//
	// Authors: Lasse Collin
	// Joachim Henke
	//
	// This file has been put into the public domain.
	// You can do whatever you want with this file.
	//
	///////////////////////////////////////////////////////////////////////////////

	#ifndef TUKLIB_INTEGER_H
	#define TUKLIB_INTEGER_H

	#include "tuklib_common.h"


	////////////////////////////////////////
	// Operating system specific features //
	////////////////////////////////////////

	#if defined(HAVE_BYTESWAP_H)
	// glibc, uClibc, dietlibc
	# include <byteswap.h>
	# ifdef HAVE_BSWAP_16
	# define bswap16(num) bswap_16(num)
	# endif
	# ifdef HAVE_BSWAP_32
	# define bswap32(num) bswap_32(num)
	# endif
	# ifdef HAVE_BSWAP_64
	# define bswap64(num) bswap_64(num)
	# endif

	#elif defined(HAVE_SYS_ENDIAN_H)
	// *BSDs and Darwin
	# include <sys/endian.h>

	#elif defined(HAVE_SYS_BYTEORDER_H)
	// Solaris
	# include <sys/byteorder.h>
	# ifdef BSWAP_16
	# define bswap16(num) BSWAP_16(num)
	# endif
	# ifdef BSWAP_32
	# define bswap32(num) BSWAP_32(num)
	# endif
	# ifdef BSWAP_64
	# define bswap64(num) BSWAP_64(num)
	# endif
	# ifdef BE_16
	# define conv16be(num) BE_16(num)
	# endif
	# ifdef BE_32
	# define conv32be(num) BE_32(num)
	# endif
	# ifdef BE_64
	# define conv64be(num) BE_64(num)
	# endif
	# ifdef LE_16
	# define conv16le(num) LE_16(num)
	# endif
	# ifdef LE_32
	# define conv32le(num) LE_32(num)
	# endif
	# ifdef LE_64
	# define conv64le(num) LE_64(num)
	# endif
	#endif


	///////////////////
	// Byte swapping //
	///////////////////

	#ifndef bswap16
	# define bswap16(num) \
	(((uint16_t)(num) << 8) \| ((uint16_t)(num) >> 8))
	#endif

	#ifndef bswap32
	# define bswap32(num) \
	( (((uint32_t)(num) << 24) ) \
	\| (((uint32_t)(num) << 8) & UINT32_C(0x00FF0000)) \
	\| (((uint32_t)(num) >> 8) & UINT32_C(0x0000FF00)) \
	\| (((uint32_t)(num) >> 24) ) )
	#endif

	#ifndef bswap64
	# define bswap64(num) \
	( (((uint64_t)(num) << 56) ) \
	\| (((uint64_t)(num) << 40) & UINT64_C(0x00FF000000000000)) \
	\| (((uint64_t)(num) << 24) & UINT64_C(0x0000FF0000000000)) \
	\| (((uint64_t)(num) << 8) & UINT64_C(0x000000FF00000000)) \
	\| (((uint64_t)(num) >> 8) & UINT64_C(0x00000000FF000000)) \
	\| (((uint64_t)(num) >> 24) & UINT64_C(0x0000000000FF0000)) \
	\| (((uint64_t)(num) >> 40) & UINT64_C(0x000000000000FF00)) \
	\| (((uint64_t)(num) >> 56) ) )
	#endif

	// Define conversion macros using the basic byte swapping macros.
	#ifdef WORDS_BIGENDIAN
	# ifndef conv16be
	# define conv16be(num) ((uint16_t)(num))
	# endif
	# ifndef conv32be
	# define conv32be(num) ((uint32_t)(num))
	# endif
	# ifndef conv64be
	# define conv64be(num) ((uint64_t)(num))
	# endif
	# ifndef conv16le
	# define conv16le(num) bswap16(num)
	# endif
	# ifndef conv32le
	# define conv32le(num) bswap32(num)
	# endif
	# ifndef conv64le
	# define conv64le(num) bswap64(num)
	# endif
	#else
	# ifndef conv16be
	# define conv16be(num) bswap16(num)
	# endif
	# ifndef conv32be
	# define conv32be(num) bswap32(num)
	# endif
	# ifndef conv64be
	# define conv64be(num) bswap64(num)
	# endif
	# ifndef conv16le
	# define conv16le(num) ((uint16_t)(num))
	# endif
	# ifndef conv32le
	# define conv32le(num) ((uint32_t)(num))
	# endif
	# ifndef conv64le
	# define conv64le(num) ((uint64_t)(num))
	# endif
	#endif


	//////////////////////////////
	// Aligned reads and writes //
	//////////////////////////////

	static inline uint16_t
	read16be(const uint8_t *buf)
	{
	uint16_t num = (const uint16_t )buf;
	return conv16be(num);
	}


	static inline uint16_t
	read16le(const uint8_t *buf)
	{
	uint16_t num = (const uint16_t )buf;
	return conv16le(num);
	}


	static inline uint32_t
	read32be(const uint8_t *buf)
	{
	uint32_t num = (const uint32_t )buf;
	return conv32be(num);
	}


	static inline uint32_t
	read32le(const uint8_t *buf)
	{
	uint32_t num = (const uint32_t )buf;
	return conv32le(num);
	}


	static inline uint64_t
	read64be(const uint8_t *buf)
	{
	uint64_t num = (const uint64_t )buf;
	return conv64be(num);
	}


	static inline uint64_t
	read64le(const uint8_t *buf)
	{
	uint64_t num = (const uint64_t )buf;
	return conv64le(num);
	}


	// NOTE: Possible byte swapping must be done in a macro to allow GCC
	// to optimize byte swapping of constants when using glibc's or *BSD's
	// byte swapping macros. The actual write is done in an inline function
	// to make type checking of the buf pointer possible similarly to readXXYe()
	// functions.

	#define write16be(buf, num) write16ne((buf), conv16be(num))
	#define write16le(buf, num) write16ne((buf), conv16le(num))
	#define write32be(buf, num) write32ne((buf), conv32be(num))
	#define write32le(buf, num) write32ne((buf), conv32le(num))
	#define write64be(buf, num) write64ne((buf), conv64be(num))
	#define write64le(buf, num) write64ne((buf), conv64le(num))


	static inline void
	write16ne(uint8_t *buf, uint16_t num)
	{
	(uint16_t )buf = num;
	return;
	}


	static inline void
	write32ne(uint8_t *buf, uint32_t num)
	{
	(uint32_t )buf = num;
	return;
	}


	static inline void
	write64ne(uint8_t *buf, uint64_t num)
	{
	(uint64_t )buf = num;
	return;
	}


	////////////////////////////////
	// Unaligned reads and writes //
	////////////////////////////////

	// NOTE: TUKLIB_FAST_UNALIGNED_ACCESS indicates only support for 16-bit and
	// 32-bit unaligned integer loads and stores. It's possible that 64-bit
	// unaligned access doesn't work or is slower than byte-by-byte access.
	// Since unaligned 64-bit is probably not needed as often as 16-bit or
	// 32-bit, we simply don't support 64-bit unaligned access for now.
	#ifdef TUKLIB_FAST_UNALIGNED_ACCESS
	# define unaligned_read16be read16be
	# define unaligned_read16le read16le
	# define unaligned_read32be read32be
	# define unaligned_read32le read32le
	# define unaligned_write16be write16be
	# define unaligned_write16le write16le
	# define unaligned_write32be write32be
	# define unaligned_write32le write32le

	#else

	static inline uint16_t
	unaligned_read16be(const uint8_t *buf)
	{
	uint16_t num = ((uint16_t)buf[0] << 8) \| (uint16_t)buf[1];
	return num;
	}


	static inline uint16_t
	unaligned_read16le(const uint8_t *buf)
	{
	uint16_t num = ((uint16_t)buf[0]) \| ((uint16_t)buf[1] << 8);
	return num;
	}


	static inline uint32_t
	unaligned_read32be(const uint8_t *buf)
	{
	uint32_t num = (uint32_t)buf[0] << 24;
	num \|= (uint32_t)buf[1] << 16;
	num \|= (uint32_t)buf[2] << 8;
	num \|= (uint32_t)buf[3];
	return num;
	}


	static inline uint32_t
	unaligned_read32le(const uint8_t *buf)
	{
	uint32_t num = (uint32_t)buf[0];
	num \|= (uint32_t)buf[1] << 8;
	num \|= (uint32_t)buf[2] << 16;
	num \|= (uint32_t)buf[3] << 24;
	return num;
	}


	static inline void
	unaligned_write16be(uint8_t *buf, uint16_t num)
	{
	buf[0] = num >> 8;
	buf[1] = num;
	return;
	}


	static inline void
	unaligned_write16le(uint8_t *buf, uint16_t num)
	{
	buf[0] = num;
	buf[1] = num >> 8;
	return;
	}


	static inline void
	unaligned_write32be(uint8_t *buf, uint32_t num)
	{
	buf[0] = num >> 24;
	buf[1] = num >> 16;
	buf[2] = num >> 8;
	buf[3] = num;
	return;
	}


	static inline void
	unaligned_write32le(uint8_t *buf, uint32_t num)
	{
	buf[0] = num;
	buf[1] = num >> 8;
	buf[2] = num >> 16;
	buf[3] = num >> 24;
	return;
	}

	#endif


	static inline uint32_t
	bsr32(uint32_t n)
	{
	// Check for ICC first, since it tends to define __GNUC__ too.
	#if defined(__INTEL_COMPILER)
	return _bit_scan_reverse(n);

	#elif TUKLIB_GNUC_REQ(3, 4) && UINT_MAX == UINT32_MAX
	// GCC >= 3.4 has __builtin_clz(), which gives good results on
	// multiple architectures. On x86, __builtin_clz() ^ 31U becomes
	// either plain BSR (so the XOR gets optimized away) or LZCNT and
	// XOR (if -march indicates that SSE4a instructions are supported).
	return __builtin_clz(n) ^ 31U;

	#elif defined(__GNUC__) && (defined(__i386__) \|\| defined(__x86_64__))
	uint32_t i;
	__asm__("bsrl %1, %0" : "=r" (i) : "rm" (n));
	return i;

	#elif defined(_MSC_VER) && _MSC_VER >= 1400
	// MSVC isn't supported by tuklib, but since this code exists,
	// it doesn't hurt to have it here anyway.
	uint32_t i;
	_BitScanReverse((DWORD *)&i, n);
	return i;

	#else
	uint32_t i = 31;

	if ((n & UINT32_C(0xFFFF0000)) == 0) {
	n <<= 16;
	i = 15;
	}

	if ((n & UINT32_C(0xFF000000)) == 0) {
	n <<= 8;
	i -= 8;
	}

	if ((n & UINT32_C(0xF0000000)) == 0) {
	n <<= 4;
	i -= 4;
	}

	if ((n & UINT32_C(0xC0000000)) == 0) {
	n <<= 2;
	i -= 2;
	}

	if ((n & UINT32_C(0x80000000)) == 0)
	--i;

	return i;
	#endif
	}


	static inline uint32_t
	clz32(uint32_t n)
	{
	#if defined(__INTEL_COMPILER)
	return _bit_scan_reverse(n) ^ 31U;

	#elif TUKLIB_GNUC_REQ(3, 4) && UINT_MAX == UINT32_MAX
	return __builtin_clz(n);

	#elif defined(__GNUC__) && (defined(__i386__) \|\| defined(__x86_64__))
	uint32_t i;
	__asm__("bsrl %1, %0\n\t"
	"xorl $31, %0"
	: "=r" (i) : "rm" (n));
	return i;

	#elif defined(_MSC_VER) && _MSC_VER >= 1400
	uint32_t i;
	_BitScanReverse((DWORD *)&i, n);
	return i ^ 31U;

	#else
	uint32_t i = 0;

	if ((n & UINT32_C(0xFFFF0000)) == 0) {
	n <<= 16;
	i = 16;
	}

	if ((n & UINT32_C(0xFF000000)) == 0) {
	n <<= 8;
	i += 8;
	}

	if ((n & UINT32_C(0xF0000000)) == 0) {
	n <<= 4;
	i += 4;
	}

	if ((n & UINT32_C(0xC0000000)) == 0) {
	n <<= 2;
	i += 2;
	}

	if ((n & UINT32_C(0x80000000)) == 0)
	++i;

	return i;
	#endif
	}


	static inline uint32_t
	ctz32(uint32_t n)
	{
	#if defined(__INTEL_COMPILER)
	return _bit_scan_forward(n);

	#elif TUKLIB_GNUC_REQ(3, 4) && UINT_MAX >= UINT32_MAX
	return __builtin_ctz(n);

	#elif defined(__GNUC__) && (defined(__i386__) \|\| defined(__x86_64__))
	uint32_t i;
	__asm__("bsfl %1, %0" : "=r" (i) : "rm" (n));
	return i;

	#elif defined(_MSC_VER) && _MSC_VER >= 1400
	uint32_t i;
	_BitScanForward((DWORD *)&i, n);
	return i;

	#else
	uint32_t i = 0;

	if ((n & UINT32_C(0x0000FFFF)) == 0) {
	n >>= 16;
	i = 16;
	}

	if ((n & UINT32_C(0x000000FF)) == 0) {
	n >>= 8;
	i += 8;
	}

	if ((n & UINT32_C(0x0000000F)) == 0) {
	n >>= 4;
	i += 4;
	}

	if ((n & UINT32_C(0x00000003)) == 0) {
	n >>= 2;
	i += 2;
	}

	if ((n & UINT32_C(0x00000001)) == 0)
	++i;

	return i;
	#endif
	}

	#define bsf32 ctz32

	#endif