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Diffstat (limited to 'src/common/tuklib_integer.h')
| -rw-r--r-- | src/common/tuklib_integer.h | 946 |
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diff --git a/src/common/tuklib_integer.h b/src/common/tuklib_integer.h new file mode 100644 index 0000000..e22aa8a --- /dev/null +++ b/src/common/tuklib_integer.h @@ -0,0 +1,946 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file tuklib_integer.h +/// \brief Various integer and bit operations +/// +/// This file provides macros or functions to do some basic integer and bit +/// operations. +/// +/// Native endian inline functions (XX = 16, 32, or 64): +/// - Unaligned native endian reads: readXXne(ptr) +/// - Unaligned native endian writes: writeXXne(ptr, num) +/// - Aligned native endian reads: aligned_readXXne(ptr) +/// - Aligned native endian writes: aligned_writeXXne(ptr, num) +/// +/// Endianness-converting integer operations (these can be macros!) +/// (XX = 16, 32, or 64; Y = b or l): +/// - Byte swapping: bswapXX(num) +/// - Byte order conversions to/from native (byteswaps if Y isn't +/// the native endianness): convXXYe(num) +/// - Unaligned reads: readXXYe(ptr) +/// - Unaligned writes: writeXXYe(ptr, num) +/// - Aligned reads: aligned_readXXYe(ptr) +/// - Aligned writes: aligned_writeXXYe(ptr, num) +/// +/// Since the above can macros, the arguments should have no side effects +/// because they may be evaluated more than once. +/// +/// Bit scan operations for non-zero 32-bit integers (inline functions): +/// - 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" +#include <string.h> + +// Newer Intel C compilers require immintrin.h for _bit_scan_reverse() +// and such functions. +#if defined(__INTEL_COMPILER) && (__INTEL_COMPILER >= 1500) +# include <immintrin.h> +// Only include <intrin.h> when it is needed. GCC and Clang can both +// use __builtin's, so we only need Windows instrincs when using MSVC. +// GCC and Clang can set _MSC_VER on Windows, so we need to exclude these +// cases explicitly. +#elif defined(_MSC_VER) && !TUKLIB_GNUC_REQ(3, 4) && !defined(__clang__) +# include <intrin.h> +#endif + + +/////////////////// +// Byte swapping // +/////////////////// + +#if defined(HAVE___BUILTIN_BSWAPXX) + // GCC >= 4.8 and Clang +# define bswap16(n) __builtin_bswap16(n) +# define bswap32(n) __builtin_bswap32(n) +# define bswap64(n) __builtin_bswap64(n) + +#elif 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 + +#ifndef bswap16 +# define bswap16(n) (uint16_t)( \ + (((n) & 0x00FFU) << 8) \ + | (((n) & 0xFF00U) >> 8) \ + ) +#endif + +#ifndef bswap32 +# define bswap32(n) (uint32_t)( \ + (((n) & UINT32_C(0x000000FF)) << 24) \ + | (((n) & UINT32_C(0x0000FF00)) << 8) \ + | (((n) & UINT32_C(0x00FF0000)) >> 8) \ + | (((n) & UINT32_C(0xFF000000)) >> 24) \ + ) +#endif + +#ifndef bswap64 +# define bswap64(n) (uint64_t)( \ + (((n) & UINT64_C(0x00000000000000FF)) << 56) \ + | (((n) & UINT64_C(0x000000000000FF00)) << 40) \ + | (((n) & UINT64_C(0x0000000000FF0000)) << 24) \ + | (((n) & UINT64_C(0x00000000FF000000)) << 8) \ + | (((n) & UINT64_C(0x000000FF00000000)) >> 8) \ + | (((n) & UINT64_C(0x0000FF0000000000)) >> 24) \ + | (((n) & UINT64_C(0x00FF000000000000)) >> 40) \ + | (((n) & UINT64_C(0xFF00000000000000)) >> 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 + + +//////////////////////////////// +// Unaligned reads and writes // +//////////////////////////////// + +// No-strict-align archs like x86-64 +// --------------------------------- +// +// The traditional way of casting e.g. *(const uint16_t *)uint8_pointer +// is bad even if the uint8_pointer is properly aligned because this kind +// of casts break strict aliasing rules and result in undefined behavior. +// With unaligned pointers it's even worse: compilers may emit vector +// instructions that require aligned pointers even if non-vector +// instructions work with unaligned pointers. +// +// Using memcpy() is the standard compliant way to do unaligned access. +// Many modern compilers inline it so there is no function call overhead. +// For those compilers that don't handle the memcpy() method well, the +// old casting method (that violates strict aliasing) can be requested at +// build time. A third method, casting to a packed struct, would also be +// an option but isn't provided to keep things simpler (it's already a mess). +// Hopefully this is flexible enough in practice. +// +// Some compilers on x86-64 like Clang >= 10 and GCC >= 5.1 detect that +// +// buf[0] | (buf[1] << 8) +// +// reads a 16-bit value and can emit a single 16-bit load and produce +// identical code than with the memcpy() method. In other cases Clang and GCC +// produce either the same or better code with memcpy(). For example, Clang 9 +// on x86-64 can detect 32-bit load but not 16-bit load. +// +// MSVC uses unaligned access with the memcpy() method but emits byte-by-byte +// code for "buf[0] | (buf[1] << 8)". +// +// Conclusion: The memcpy() method is the best choice when unaligned access +// is supported. +// +// Strict-align archs like SPARC +// ----------------------------- +// +// GCC versions from around 4.x to to at least 13.2.0 produce worse code +// from the memcpy() method than from simple byte-by-byte shift-or code +// when reading a 32-bit integer: +// +// (1) It may be constructed on stack using using four 8-bit loads, +// four 8-bit stores to stack, and finally one 32-bit load from stack. +// +// (2) Especially with -Os, an actual memcpy() call may be emitted. +// +// This is true on at least on ARM, ARM64, SPARC, SPARC64, MIPS64EL, and +// RISC-V. Of these, ARM, ARM64, and RISC-V support unaligned access in +// some processors but not all so this is relevant only in the case when +// GCC assumes that unaligned is not supported or -mstrict-align or +// -mno-unaligned-access is used. +// +// For Clang it makes little difference. ARM64 with -O2 -mstrict-align +// was one the very few with a minor difference: the memcpy() version +// was one instruction longer. +// +// Conclusion: At least in case of GCC and Clang, byte-by-byte code is +// the best choise for strict-align archs to do unaligned access. +// +// See also: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111502 +// +// Thanks to <https://godbolt.org/> it was easy to test different compilers. +// The following is for little endian targets: +/* +#include <stdint.h> +#include <string.h> + +uint32_t bytes16(const uint8_t *b) +{ + return (uint32_t)b[0] + | ((uint32_t)b[1] << 8); +} + +uint32_t copy16(const uint8_t *b) +{ + uint16_t v; + memcpy(&v, b, sizeof(v)); + return v; +} + +uint32_t bytes32(const uint8_t *b) +{ + return (uint32_t)b[0] + | ((uint32_t)b[1] << 8) + | ((uint32_t)b[2] << 16) + | ((uint32_t)b[3] << 24); +} + +uint32_t copy32(const uint8_t *b) +{ + uint32_t v; + memcpy(&v, b, sizeof(v)); + return v; +} + +void wbytes16(uint8_t *b, uint16_t v) +{ + b[0] = (uint8_t)v; + b[1] = (uint8_t)(v >> 8); +} + +void wcopy16(uint8_t *b, uint16_t v) +{ + memcpy(b, &v, sizeof(v)); +} + +void wbytes32(uint8_t *b, uint32_t v) +{ + b[0] = (uint8_t)v; + b[1] = (uint8_t)(v >> 8); + b[2] = (uint8_t)(v >> 16); + b[3] = (uint8_t)(v >> 24); +} + +void wcopy32(uint8_t *b, uint32_t v) +{ + memcpy(b, &v, sizeof(v)); +} +*/ + + +#ifdef TUKLIB_FAST_UNALIGNED_ACCESS + +static inline uint16_t +read16ne(const uint8_t *buf) +{ +#ifdef TUKLIB_USE_UNSAFE_TYPE_PUNNING + return *(const uint16_t *)buf; +#else + uint16_t num; + memcpy(&num, buf, sizeof(num)); + return num; +#endif +} + + +static inline uint32_t +read32ne(const uint8_t *buf) +{ +#ifdef TUKLIB_USE_UNSAFE_TYPE_PUNNING + return *(const uint32_t *)buf; +#else + uint32_t num; + memcpy(&num, buf, sizeof(num)); + return num; +#endif +} + + +static inline uint64_t +read64ne(const uint8_t *buf) +{ +#ifdef TUKLIB_USE_UNSAFE_TYPE_PUNNING + return *(const uint64_t *)buf; +#else + uint64_t num; + memcpy(&num, buf, sizeof(num)); + return num; +#endif +} + + +static inline void +write16ne(uint8_t *buf, uint16_t num) +{ +#ifdef TUKLIB_USE_UNSAFE_TYPE_PUNNING + *(uint16_t *)buf = num; +#else + memcpy(buf, &num, sizeof(num)); +#endif + return; +} + + +static inline void +write32ne(uint8_t *buf, uint32_t num) +{ +#ifdef TUKLIB_USE_UNSAFE_TYPE_PUNNING + *(uint32_t *)buf = num; +#else + memcpy(buf, &num, sizeof(num)); +#endif + return; +} + + +static inline void +write64ne(uint8_t *buf, uint64_t num) +{ +#ifdef TUKLIB_USE_UNSAFE_TYPE_PUNNING + *(uint64_t *)buf = num; +#else + memcpy(buf, &num, sizeof(num)); +#endif + return; +} + + +static inline uint16_t +read16be(const uint8_t *buf) +{ + uint16_t num = read16ne(buf); + return conv16be(num); +} + + +static inline uint16_t +read16le(const uint8_t *buf) +{ + uint16_t num = read16ne(buf); + return conv16le(num); +} + + +static inline uint32_t +read32be(const uint8_t *buf) +{ + uint32_t num = read32ne(buf); + return conv32be(num); +} + + +static inline uint32_t +read32le(const uint8_t *buf) +{ + uint32_t num = read32ne(buf); + return conv32le(num); +} + + +static inline uint64_t +read64be(const uint8_t *buf) +{ + uint64_t num = read64ne(buf); + return conv64be(num); +} + + +static inline uint64_t +read64le(const uint8_t *buf) +{ + uint64_t num = read64ne(buf); + return conv64le(num); +} + + +// NOTE: Possible byte swapping must be done in a macro to allow the compiler +// 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. +#define write16be(buf, num) write16ne(buf, conv16be(num)) +#define write32be(buf, num) write32ne(buf, conv32be(num)) +#define write64be(buf, num) write64ne(buf, conv64be(num)) +#define write16le(buf, num) write16ne(buf, conv16le(num)) +#define write32le(buf, num) write32ne(buf, conv32le(num)) +#define write64le(buf, num) write64ne(buf, conv64le(num)) + +#else + +#ifdef WORDS_BIGENDIAN +# define read16ne read16be +# define read32ne read32be +# define read64ne read64be +# define write16ne write16be +# define write32ne write32be +# define write64ne write64be +#else +# define read16ne read16le +# define read32ne read32le +# define read64ne read64le +# define write16ne write16le +# define write32ne write32le +# define write64ne write64le +#endif + + +static inline uint16_t +read16be(const uint8_t *buf) +{ + uint16_t num = ((uint16_t)buf[0] << 8) | (uint16_t)buf[1]; + return num; +} + + +static inline uint16_t +read16le(const uint8_t *buf) +{ + uint16_t num = ((uint16_t)buf[0]) | ((uint16_t)buf[1] << 8); + return num; +} + + +static inline uint32_t +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 +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 uint64_t +read64be(const uint8_t *buf) +{ + uint64_t num = (uint64_t)buf[0] << 56; + num |= (uint64_t)buf[1] << 48; + num |= (uint64_t)buf[2] << 40; + num |= (uint64_t)buf[3] << 32; + num |= (uint64_t)buf[4] << 24; + num |= (uint64_t)buf[5] << 16; + num |= (uint64_t)buf[6] << 8; + num |= (uint64_t)buf[7]; + return num; +} + + +static inline uint64_t +read64le(const uint8_t *buf) +{ + uint64_t num = (uint64_t)buf[0]; + num |= (uint64_t)buf[1] << 8; + num |= (uint64_t)buf[2] << 16; + num |= (uint64_t)buf[3] << 24; + num |= (uint64_t)buf[4] << 32; + num |= (uint64_t)buf[5] << 40; + num |= (uint64_t)buf[6] << 48; + num |= (uint64_t)buf[7] << 56; + return num; +} + + +static inline void +write16be(uint8_t *buf, uint16_t num) +{ + buf[0] = (uint8_t)(num >> 8); + buf[1] = (uint8_t)num; + return; +} + + +static inline void +write16le(uint8_t *buf, uint16_t num) +{ + buf[0] = (uint8_t)num; + buf[1] = (uint8_t)(num >> 8); + return; +} + + +static inline void +write32be(uint8_t *buf, uint32_t num) +{ + buf[0] = (uint8_t)(num >> 24); + buf[1] = (uint8_t)(num >> 16); + buf[2] = (uint8_t)(num >> 8); + buf[3] = (uint8_t)num; + return; +} + + +static inline void +write32le(uint8_t *buf, uint32_t num) +{ + buf[0] = (uint8_t)num; + buf[1] = (uint8_t)(num >> 8); + buf[2] = (uint8_t)(num >> 16); + buf[3] = (uint8_t)(num >> 24); + return; +} + + +static inline void +write64be(uint8_t *buf, uint64_t num) +{ + buf[0] = (uint8_t)(num >> 56); + buf[1] = (uint8_t)(num >> 48); + buf[2] = (uint8_t)(num >> 40); + buf[3] = (uint8_t)(num >> 32); + buf[4] = (uint8_t)(num >> 24); + buf[5] = (uint8_t)(num >> 16); + buf[6] = (uint8_t)(num >> 8); + buf[7] = (uint8_t)num; + return; +} + + +static inline void +write64le(uint8_t *buf, uint64_t num) +{ + buf[0] = (uint8_t)num; + buf[1] = (uint8_t)(num >> 8); + buf[2] = (uint8_t)(num >> 16); + buf[3] = (uint8_t)(num >> 24); + buf[4] = (uint8_t)(num >> 32); + buf[5] = (uint8_t)(num >> 40); + buf[6] = (uint8_t)(num >> 48); + buf[7] = (uint8_t)(num >> 56); + return; +} + +#endif + + +////////////////////////////// +// Aligned reads and writes // +////////////////////////////// + +// Separate functions for aligned reads and writes are provided since on +// strict-align archs aligned access is much faster than unaligned access. +// +// Just like in the unaligned case, memcpy() is needed to avoid +// strict aliasing violations. However, on archs that don't support +// unaligned access the compiler cannot know that the pointers given +// to memcpy() are aligned which results in slow code. As of C11 there is +// no standard way to tell the compiler that we know that the address is +// aligned but some compilers have language extensions to do that. With +// such language extensions the memcpy() method gives excellent results. +// +// What to do on a strict-align system when no known language extentensions +// are available? Falling back to byte-by-byte access would be safe but ruin +// optimizations that have been made specifically with aligned access in mind. +// As a compromise, aligned reads will fall back to non-compliant type punning +// but aligned writes will be byte-by-byte, that is, fast reads are preferred +// over fast writes. This obviously isn't great but hopefully it's a working +// compromise for now. +// +// __builtin_assume_aligned is support by GCC >= 4.7 and clang >= 3.6. +#ifdef HAVE___BUILTIN_ASSUME_ALIGNED +# define tuklib_memcpy_aligned(dest, src, size) \ + memcpy(dest, __builtin_assume_aligned(src, size), size) +#else +# define tuklib_memcpy_aligned(dest, src, size) \ + memcpy(dest, src, size) +# ifndef TUKLIB_FAST_UNALIGNED_ACCESS +# define TUKLIB_USE_UNSAFE_ALIGNED_READS 1 +# endif +#endif + + +static inline uint16_t +aligned_read16ne(const uint8_t *buf) +{ +#if defined(TUKLIB_USE_UNSAFE_TYPE_PUNNING) \ + || defined(TUKLIB_USE_UNSAFE_ALIGNED_READS) + return *(const uint16_t *)buf; +#else + uint16_t num; + tuklib_memcpy_aligned(&num, buf, sizeof(num)); + return num; +#endif +} + + +static inline uint32_t +aligned_read32ne(const uint8_t *buf) +{ +#if defined(TUKLIB_USE_UNSAFE_TYPE_PUNNING) \ + || defined(TUKLIB_USE_UNSAFE_ALIGNED_READS) + return *(const uint32_t *)buf; +#else + uint32_t num; + tuklib_memcpy_aligned(&num, buf, sizeof(num)); + return num; +#endif +} + + +static inline uint64_t +aligned_read64ne(const uint8_t *buf) +{ +#if defined(TUKLIB_USE_UNSAFE_TYPE_PUNNING) \ + || defined(TUKLIB_USE_UNSAFE_ALIGNED_READS) + return *(const uint64_t *)buf; +#else + uint64_t num; + tuklib_memcpy_aligned(&num, buf, sizeof(num)); + return num; +#endif +} + + +static inline void +aligned_write16ne(uint8_t *buf, uint16_t num) +{ +#ifdef TUKLIB_USE_UNSAFE_TYPE_PUNNING + *(uint16_t *)buf = num; +#else + tuklib_memcpy_aligned(buf, &num, sizeof(num)); +#endif + return; +} + + +static inline void +aligned_write32ne(uint8_t *buf, uint32_t num) +{ +#ifdef TUKLIB_USE_UNSAFE_TYPE_PUNNING + *(uint32_t *)buf = num; +#else + tuklib_memcpy_aligned(buf, &num, sizeof(num)); +#endif + return; +} + + +static inline void +aligned_write64ne(uint8_t *buf, uint64_t num) +{ +#ifdef TUKLIB_USE_UNSAFE_TYPE_PUNNING + *(uint64_t *)buf = num; +#else + tuklib_memcpy_aligned(buf, &num, sizeof(num)); +#endif + return; +} + + +static inline uint16_t +aligned_read16be(const uint8_t *buf) +{ + uint16_t num = aligned_read16ne(buf); + return conv16be(num); +} + + +static inline uint16_t +aligned_read16le(const uint8_t *buf) +{ + uint16_t num = aligned_read16ne(buf); + return conv16le(num); +} + + +static inline uint32_t +aligned_read32be(const uint8_t *buf) +{ + uint32_t num = aligned_read32ne(buf); + return conv32be(num); +} + + +static inline uint32_t +aligned_read32le(const uint8_t *buf) +{ + uint32_t num = aligned_read32ne(buf); + return conv32le(num); +} + + +static inline uint64_t +aligned_read64be(const uint8_t *buf) +{ + uint64_t num = aligned_read64ne(buf); + return conv64be(num); +} + + +static inline uint64_t +aligned_read64le(const uint8_t *buf) +{ + uint64_t num = aligned_read64ne(buf); + return conv64le(num); +} + + +// These need to be macros like in the unaligned case. +#define aligned_write16be(buf, num) aligned_write16ne((buf), conv16be(num)) +#define aligned_write16le(buf, num) aligned_write16ne((buf), conv16le(num)) +#define aligned_write32be(buf, num) aligned_write32ne((buf), conv32be(num)) +#define aligned_write32le(buf, num) aligned_write32ne((buf), conv32le(num)) +#define aligned_write64be(buf, num) aligned_write64ne((buf), conv64be(num)) +#define aligned_write64le(buf, num) aligned_write64ne((buf), conv64le(num)) + + +//////////////////// +// Bit operations // +//////////////////// + +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) || defined(__clang__)) && 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 (uint32_t)__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) + unsigned long i; + _BitScanReverse(&i, n); + return i; + +#else + uint32_t i = 31; + + if ((n & 0xFFFF0000) == 0) { + n <<= 16; + i = 15; + } + + if ((n & 0xFF000000) == 0) { + n <<= 8; + i -= 8; + } + + if ((n & 0xF0000000) == 0) { + n <<= 4; + i -= 4; + } + + if ((n & 0xC0000000) == 0) { + n <<= 2; + i -= 2; + } + + if ((n & 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) || defined(__clang__)) && UINT_MAX == UINT32_MAX + return (uint32_t)__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) + unsigned long i; + _BitScanReverse(&i, n); + return i ^ 31U; + +#else + uint32_t i = 0; + + if ((n & 0xFFFF0000) == 0) { + n <<= 16; + i = 16; + } + + if ((n & 0xFF000000) == 0) { + n <<= 8; + i += 8; + } + + if ((n & 0xF0000000) == 0) { + n <<= 4; + i += 4; + } + + if ((n & 0xC0000000) == 0) { + n <<= 2; + i += 2; + } + + if ((n & 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) || defined(__clang__)) && UINT_MAX >= UINT32_MAX + return (uint32_t)__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) + unsigned long i; + _BitScanForward(&i, n); + return i; + +#else + uint32_t i = 0; + + if ((n & 0x0000FFFF) == 0) { + n >>= 16; + i = 16; + } + + if ((n & 0x000000FF) == 0) { + n >>= 8; + i += 8; + } + + if ((n & 0x0000000F) == 0) { + n >>= 4; + i += 4; + } + + if ((n & 0x00000003) == 0) { + n >>= 2; + i += 2; + } + + if ((n & 0x00000001) == 0) + ++i; + + return i; +#endif +} + +#define bsf32 ctz32 + +#endif |