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diff --git a/include/bitops.h b/include/bitops.h
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+/*
+ * No copyright is claimed. This code is in the public domain; do with
+ * it what you wish.
+ *
+ * Written by Karel Zak <kzak@redhat.com>
+ */
+#ifndef BITOPS_H
+#define BITOPS_H
+
+#include <stdint.h>
+#include <sys/param.h>
+
+#if defined(HAVE_BYTESWAP_H)
+# include <byteswap.h>
+#endif
+
+#if defined(HAVE_ENDIAN_H)
+# include <endian.h>
+#elif defined(HAVE_SYS_ENDIAN_H) /* BSDs have them here */
+# include <sys/endian.h>
+#endif
+
+#if !(defined(HAVE_BYTESWAP_H) && defined(HAVE_ENDIAN_H))
+/*
+ * When both byteswap.h and endian.h are preseent, the proper macros are defined
+ * as those files are glibc compatible. Otherwise, compensate for the slightly
+ * different interfaces between the different BSDs.
+ */
+#if defined(__OpenBSD__)
+# include <sys/types.h>
+# define be16toh(x) betoh16(x)
+# define be32toh(x) betoh32(x)
+# define be64toh(x) betoh64(x)
+#elif defined(__NetBSD__) || defined(__FreeBSD__) || defined(__DragonFly__)
+# define bswap_16(x) bswap16(x)
+# define bswap_32(x) bswap32(x)
+# define bswap_64(x) bswap64(x)
+#elif defined(__APPLE__)
+# include <libkern/OSByteOrder.h>
+# define htobe16(x) OSSwapHostToBigInt16(x)
+# define htole16(x) OSSwapHostToLittleInt16(x)
+# define be16toh(x) OSSwapBigToHostInt16(x)
+# define le16toh(x) OSSwapLittleToHostInt16(x)
+# define htobe32(x) OSSwapHostToBigInt32(x)
+# define htole32(x) OSSwapHostToLittleInt32(x)
+# define be32toh(x) OSSwapBigToHostInt32(x)
+# define le32toh(x) OSSwapLittleToHostInt32(x)
+# define htobe64(x) OSSwapHostToBigInt64(x)
+# define htole64(x) OSSwapHostToLittleInt64(x)
+# define be64toh(x) OSSwapBigToHostInt64(x)
+# define le64toh(x) OSSwapLittleToHostInt64(x)
+# define bswap_16(x) OSSwapInt16(x)
+# define bswap_32(x) OSSwapInt32(x)
+# define bswap_64(x) OSSwapInt64(x)
+#endif
+#endif
+
+/*
+ * Fallbacks
+ * casts are necessary for constants, because we never know how for sure
+ * how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way.
+ */
+#ifndef bswap_16
+# define bswap_16(x) ((uint16_t)( \
+ (((uint16_t)(x) & 0x00FF) << 8) | \
+ (((uint16_t)(x) & 0xFF00) >> 8)))
+#endif
+
+#ifndef bswap_32
+# define bswap_32(x) ((uint32_t)( \
+ (((uint32_t)(x) & 0x000000FF) << 24) | \
+ (((uint32_t)(x) & 0x0000FF00) << 8) | \
+ (((uint32_t)(x) & 0x00FF0000) >> 8) | \
+ (((uint32_t)(x) & 0xFF000000) >> 24)))
+#endif
+
+#ifndef bswap_64
+# define bswap_64(x) ((uint64_t)( \
+ (((uint64_t)(x) & 0x00000000000000FFULL) << 56) | \
+ (((uint64_t)(x) & 0x000000000000FF00ULL) << 40) | \
+ (((uint64_t)(x) & 0x0000000000FF0000ULL) << 24) | \
+ (((uint64_t)(x) & 0x00000000FF000000ULL) << 8) | \
+ (((uint64_t)(x) & 0x000000FF00000000ULL) >> 8) | \
+ (((uint64_t)(x) & 0x0000FF0000000000ULL) >> 24) | \
+ (((uint64_t)(x) & 0x00FF000000000000ULL) >> 40) | \
+ (((uint64_t)(x) & 0xFF00000000000000ULL) >> 56)))
+#endif
+
+#ifndef htobe16
+# if !defined(WORDS_BIGENDIAN)
+# define htobe16(x) bswap_16 (x)
+# define htole16(x) (x)
+# define be16toh(x) bswap_16 (x)
+# define le16toh(x) (x)
+# define htobe32(x) bswap_32 (x)
+# define htole32(x) (x)
+# define be32toh(x) bswap_32 (x)
+# define le32toh(x) (x)
+# define htobe64(x) bswap_64 (x)
+# define htole64(x) (x)
+# define be64toh(x) bswap_64 (x)
+# define le64toh(x) (x)
+# else
+# define htobe16(x) (x)
+# define htole16(x) bswap_16 (x)
+# define be16toh(x) (x)
+# define le16toh(x) bswap_16 (x)
+# define htobe32(x) (x)
+# define htole32(x) bswap_32 (x)
+# define be32toh(x) (x)
+# define le32toh(x) bswap_32 (x)
+# define htobe64(x) (x)
+# define htole64(x) bswap_64 (x)
+# define be64toh(x) (x)
+# define le64toh(x) bswap_64 (x)
+# endif
+#endif
+
+/*
+ * Byte swab macros (based on linux/byteorder/swab.h)
+ */
+#define swab16(x) bswap_16(x)
+#define swab32(x) bswap_32(x)
+#define swab64(x) bswap_64(x)
+
+#define cpu_to_le16(x) ((uint16_t) htole16(x))
+#define cpu_to_le32(x) ((uint32_t) htole32(x))
+#define cpu_to_le64(x) ((uint64_t) htole64(x))
+
+#define cpu_to_be16(x) ((uint16_t) htobe16(x))
+#define cpu_to_be32(x) ((uint32_t) htobe32(x))
+#define cpu_to_be64(x) ((uint64_t) htobe64(x))
+
+#define le16_to_cpu(x) ((uint16_t) le16toh(x))
+#define le32_to_cpu(x) ((uint32_t) le32toh(x))
+#define le64_to_cpu(x) ((uint64_t) le64toh(x))
+
+#define be16_to_cpu(x) ((uint16_t) be16toh(x))
+#define be32_to_cpu(x) ((uint32_t) be32toh(x))
+#define be64_to_cpu(x) ((uint64_t) be64toh(x))
+
+/*
+ * Bit map related macros. Usually provided by libc.
+ */
+#ifndef NBBY
+# define NBBY CHAR_BIT
+#endif
+
+#ifndef setbit
+# define setbit(a,i) ((a)[(i)/NBBY] |= 1<<((i)%NBBY))
+# define clrbit(a,i) ((a)[(i)/NBBY] &= ~(1<<((i)%NBBY)))
+# define isset(a,i) ((a)[(i)/NBBY] & (1<<((i)%NBBY)))
+# define isclr(a,i) (((a)[(i)/NBBY] & (1<<((i)%NBBY))) == 0)
+#endif
+
+#endif /* BITOPS_H */
+