176 lines
4.4 KiB
C
176 lines
4.4 KiB
C
#ifndef COMPAT_BSWAP_H
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#define COMPAT_BSWAP_H
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/*
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* Let's make sure we always have a sane definition for ntohl()/htonl().
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* Some libraries define those as a function call, just to perform byte
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* shifting, bringing significant overhead to what should be a simple
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* operation.
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*/
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/*
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* Default version that the compiler ought to optimize properly with
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* constant values.
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*/
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static inline uint32_t default_swab32(uint32_t val)
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{
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return (((val & 0xff000000) >> 24) |
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((val & 0x00ff0000) >> 8) |
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((val & 0x0000ff00) << 8) |
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((val & 0x000000ff) << 24));
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}
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static inline uint64_t default_bswap64(uint64_t val)
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{
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return (((val & (uint64_t)0x00000000000000ffULL) << 56) |
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((val & (uint64_t)0x000000000000ff00ULL) << 40) |
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((val & (uint64_t)0x0000000000ff0000ULL) << 24) |
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((val & (uint64_t)0x00000000ff000000ULL) << 8) |
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((val & (uint64_t)0x000000ff00000000ULL) >> 8) |
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((val & (uint64_t)0x0000ff0000000000ULL) >> 24) |
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((val & (uint64_t)0x00ff000000000000ULL) >> 40) |
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((val & (uint64_t)0xff00000000000000ULL) >> 56));
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}
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/*
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* __has_builtin is available since Clang 10 and GCC 10.
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* Below is a fallback for older compilers.
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*/
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#ifndef __has_builtin
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# define __has_builtin(x) 0
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#endif
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#undef bswap32
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#undef bswap64
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#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64) || defined(_M_ARM64))
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#include <stdlib.h>
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#define bswap32(x) _byteswap_ulong(x)
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#define bswap64(x) _byteswap_uint64(x)
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#define GIT_LITTLE_ENDIAN 1234
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#define GIT_BIG_ENDIAN 4321
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#define GIT_BYTE_ORDER GIT_LITTLE_ENDIAN
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#elif __has_builtin(__builtin_bswap32) && __has_builtin(__builtin_bswap64)
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#define bswap32(x) __builtin_bswap32((x))
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#define bswap64(x) __builtin_bswap64((x))
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#endif
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#if defined(__BYTE_ORDER) && defined(__LITTLE_ENDIAN) && defined(__BIG_ENDIAN)
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# define GIT_BYTE_ORDER __BYTE_ORDER
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# define GIT_LITTLE_ENDIAN __LITTLE_ENDIAN
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# define GIT_BIG_ENDIAN __BIG_ENDIAN
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#elif defined(BYTE_ORDER) && defined(LITTLE_ENDIAN) && defined(BIG_ENDIAN)
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# define GIT_BYTE_ORDER BYTE_ORDER
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# define GIT_LITTLE_ENDIAN LITTLE_ENDIAN
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# define GIT_BIG_ENDIAN BIG_ENDIAN
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#elif defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && defined(__ORDER_BIG_ENDIAN__)
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# define GIT_BYTE_ORDER __BYTE_ORDER__
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# define GIT_LITTLE_ENDIAN __ORDER_LITTLE_ENDIAN__
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# define GIT_BIG_ENDIAN __ORDER_BIG_ENDIAN__
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#elif !defined(GIT_BYTE_ORDER)
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# define GIT_BIG_ENDIAN 4321
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# define GIT_LITTLE_ENDIAN 1234
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# if defined(_BIG_ENDIAN) && !defined(_LITTLE_ENDIAN)
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# define GIT_BYTE_ORDER GIT_BIG_ENDIAN
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# elif defined(_LITTLE_ENDIAN) && !defined(_BIG_ENDIAN)
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# define GIT_BYTE_ORDER GIT_LITTLE_ENDIAN
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# elif defined(__THW_BIG_ENDIAN__) && !defined(__THW_LITTLE_ENDIAN__)
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# define GIT_BYTE_ORDER GIT_BIG_ENDIAN
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# elif defined(__THW_LITTLE_ENDIAN__) && !defined(__THW_BIG_ENDIAN__)
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# define GIT_BYTE_ORDER GIT_LITTLE_ENDIAN
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# else
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# error "Cannot determine endianness"
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# endif
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#endif
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#undef ntohl
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#undef htonl
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#undef ntohll
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#undef htonll
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#if GIT_BYTE_ORDER == GIT_BIG_ENDIAN
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# define ntohl(x) (x)
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# define htonl(x) (x)
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# define ntohll(x) (x)
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# define htonll(x) (x)
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#else
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# if defined(bswap32)
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# define ntohl(x) bswap32(x)
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# define htonl(x) bswap32(x)
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# else
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# define ntohl(x) default_swab32(x)
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# define htonl(x) default_swab32(x)
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# endif
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# if defined(bswap64)
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# define ntohll(x) bswap64(x)
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# define htonll(x) bswap64(x)
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# else
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# define ntohll(x) default_bswap64(x)
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# define htonll(x) default_bswap64(x)
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# endif
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#endif
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static inline uint16_t get_be16(const void *ptr)
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{
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const unsigned char *p = ptr;
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return (uint16_t)p[0] << 8 |
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(uint16_t)p[1] << 0;
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}
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static inline uint32_t get_be32(const void *ptr)
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{
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const unsigned char *p = ptr;
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return (uint32_t)p[0] << 24 |
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(uint32_t)p[1] << 16 |
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(uint32_t)p[2] << 8 |
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(uint32_t)p[3] << 0;
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}
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static inline uint64_t get_be64(const void *ptr)
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{
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const unsigned char *p = ptr;
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return (uint64_t)get_be32(&p[0]) << 32 |
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(uint64_t)get_be32(&p[4]) << 0;
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}
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static inline void put_be32(void *ptr, uint32_t value)
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{
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unsigned char *p = ptr;
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p[0] = (value >> 24) & 0xff;
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p[1] = (value >> 16) & 0xff;
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p[2] = (value >> 8) & 0xff;
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p[3] = (value >> 0) & 0xff;
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}
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static inline void put_be64(void *ptr, uint64_t value)
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{
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unsigned char *p = ptr;
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p[0] = (value >> 56) & 0xff;
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p[1] = (value >> 48) & 0xff;
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p[2] = (value >> 40) & 0xff;
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p[3] = (value >> 32) & 0xff;
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p[4] = (value >> 24) & 0xff;
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p[5] = (value >> 16) & 0xff;
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p[6] = (value >> 8) & 0xff;
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p[7] = (value >> 0) & 0xff;
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}
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#endif /* COMPAT_BSWAP_H */
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