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+///////////////////////////////////////////////////////////////////////////////
+//
+/// \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
generated by cgit v0.12 at 2024-12-29 11:47:07 (GMT)