1dfb6fd111
1. __builtin_bswap{32,64} were added in GCC 4.3, and __builtin_bswap16
was added in GCC 4.8, however, currently, the GCC requirements in
bswap.h file has >= 10. This requirement of GCC version is false for
bswap* but true for __has_builtin() (as it first was added in GCC 10.1).
As bswap* builtins were added before GCC 10, the preprocessor check will
always going to be true for bswap but will be false if GCC version is
< 10 as __has_builtin() won't be present. Since the byteswap function,
on x86-64, can boil down to a single bswap instruction, this optimization
may left behind (unless GCC do some pattern matching). To avoid this,
just use the compiler macros (for GCC: __GNUC__, clang: __GNUC__ or
__clang__) and if the compiler is neither GCC or Clang, fall-back to
native implementation.
2. Remove the useless casts (uint{16,32,64}_t) from the constants. These
constants already has their own suffix, and casting to a different type
will just get ignored as the return value already gets casts to it's
appropriate type.
3. Previously, Clang couldn't able to use __builtin_bswap* (even if it was
newer) as LLVM define __GNUC__ macro to a specific constant (usually lower
than GCC's (__GNUC__) and on my system it's 4) which is indeed < 10. The
first comment also fixes this issue.
Link: <https://gcc.gnu.org/onlinedocs/gcc-4.3.0/gcc/Other-Builtins.html>
Link: <https://gcc.gnu.org/onlinedocs/gcc-4.8.0/gcc/Other-Builtins.html>
Link: <https://libc-alpha.sourceware.narkive.com/PfaB4BGP/patch-byteswap-h-fix-gcc-ver-test-for-builtin-bswap32>
242 lines
6.8 KiB
C
242 lines
6.8 KiB
C
/*
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* 86Box A hypervisor and IBM PC system emulator that specializes in
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* running old operating systems and software designed for IBM
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* PC systems and compatibles from 1981 through fairly recent
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* system designs based on the PCI bus.
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*
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* This file is part of the 86Box distribution.
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*
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* Various definitions for portable byte-swapping.
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*
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*
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*
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* Authors: Fred N. van Kempen, <decwiz@yahoo.com>
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* neozeed,
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*
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* Copyright 2017-2018 Fred N. van Kempen.
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* Copyright 2016-2018 neozeed.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the:
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*
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* Free Software Foundation, Inc.
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* 59 Temple Place - Suite 330
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* Boston, MA 02111-1307
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* USA.
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*/
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#ifndef BSWAP_H
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#define BSWAP_H
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#include <stdint.h>
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#define bswap_16(x) \
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((uint16_t)((((x) & 0x00ffu) << 8) | \
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(((x) & 0xff00u) >> 8)))
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#define bswap_32(x) \
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((uint32_t)((((x) & 0x000000fful) << 24) | \
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(((x) & 0x0000ff00ul) << 8) | \
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(((x) & 0x00ff0000ul) >> 8) | \
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(((x) & 0xff000000ul) >> 24)))
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# define bswap_64(x) \
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((uint64_t)((((x) & 0x00000000000000ffull) << 56) | \
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(((x) & 0x000000000000ff00ull) << 40) | \
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(((x) & 0x0000000000ff0000ull) << 24) | \
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(((x) & 0x00000000ff000000ull) << 8) | \
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(((x) & 0x000000ff00000000ull) >> 8) | \
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(((x) & 0x0000ff0000000000ull) >> 24) | \
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(((x) & 0x00ff000000000000ull) >> 40) | \
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(((x) & 0xff00000000000000ull) >> 56)))
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static __inline uint16_t
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bswap16(uint16_t x)
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{
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#if defined (__GNUC__) || defined (__clang__)
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return __builtin_bswap16(x);
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#else
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return bswap_16(x);
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#endif
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}
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static __inline uint32_t
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bswap32(uint32_t x)
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{
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#if defined (__GNUC__) || defined (__clang__)
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return __builtin_bswap32(x);
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#else
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return bswap_32(x);
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#endif
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}
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static __inline uint64_t
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bswap64(uint64_t x)
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{
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#if defined (__GNUC__) || defined (__clang__)
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return __builtin_bswap64(x);
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#else
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return bswap_16(x);
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#endif
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}
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static __inline void
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bswap16s(uint16_t *s)
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{
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*s = bswap16(*s);
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}
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static __inline void
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bswap32s(uint32_t *s)
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{
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*s = bswap32(*s);
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}
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static __inline void
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bswap64s(uint64_t *s)
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{
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*s = bswap64(*s);
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}
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#if defined(WORDS_BIGENDIAN)
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# define be_bswap(v, size) (v)
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# define le_bswap(v, size) bswap##size(v)
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# define be_bswaps(v, size)
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# define le_bswaps(p, size) *p = bswap##size(*p);
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#else
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# define le_bswap(v, size) (v)
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# define be_bswap(v, size) bswap##size(v)
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# define le_bswaps(v, size)
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# define be_bswaps(p, size) *p = bswap##size(*p);
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#endif
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#define CPU_CONVERT(endian, size, type) \
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static __inline type endian##size##_to_cpu(type v) \
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{ \
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return endian##_bswap(v, size); \
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} \
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\
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static __inline type cpu_to_##endian##size(type v) \
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{ \
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return endian##_bswap(v, size); \
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} \
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\
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static __inline void endian##size##_to_cpus(type *p) \
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{ \
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endian##_bswaps(p, size) \
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} \
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\
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static __inline void cpu_to_##endian##size##s(type *p) \
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{ \
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endian##_bswaps(p, size) \
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} \
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\
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static __inline type endian##size##_to_cpup(const type *p) \
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{ \
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return endian##size##_to_cpu(*p); \
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} \
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\
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static __inline void cpu_to_##endian##size##w(type *p, type v) \
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{ \
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*p = cpu_to_##endian##size(v); \
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}
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CPU_CONVERT(be, 16, uint16_t)
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CPU_CONVERT(be, 32, uint32_t)
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CPU_CONVERT(be, 64, uint64_t)
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CPU_CONVERT(le, 16, uint16_t)
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CPU_CONVERT(le, 32, uint32_t)
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CPU_CONVERT(le, 64, uint64_t)
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/* unaligned versions (optimized for frequent unaligned accesses)*/
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#if defined(__i386__) || defined(__powerpc__)
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# define cpu_to_le16wu(p, v) cpu_to_le16w(p, v)
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# define cpu_to_le32wu(p, v) cpu_to_le32w(p, v)
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# define le16_to_cpupu(p) le16_to_cpup(p)
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# define le32_to_cpupu(p) le32_to_cpup(p)
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# define cpu_to_be16wu(p, v) cpu_to_be16w(p, v)
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# define cpu_to_be32wu(p, v) cpu_to_be32w(p, v)
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#else
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static __inline void
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cpu_to_le16wu(uint16_t *p, uint16_t v)
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{
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uint8_t *p1 = (uint8_t *) p;
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p1[0] = v & 0xff;
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p1[1] = v >> 8;
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}
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static __inline void
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cpu_to_le32wu(uint32_t *p, uint32_t v)
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{
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uint8_t *p1 = (uint8_t *) p;
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p1[0] = v;
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p1[1] = v >> 8;
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p1[2] = v >> 16;
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p1[3] = v >> 24;
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}
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static __inline uint16_t
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le16_to_cpupu(const uint16_t *p)
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{
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const uint8_t *p1 = (const uint8_t *) p;
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return p1[0] | (p1[1] << 8);
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}
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static __inline uint32_t
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le32_to_cpupu(const uint32_t *p)
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{
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const uint8_t *p1 = (const uint8_t *) p;
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return p1[0] | (p1[1] << 8) | (p1[2] << 16) | (p1[3] << 24);
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}
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static __inline void
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cpu_to_be16wu(uint16_t *p, uint16_t v)
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{
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uint8_t *p1 = (uint8_t *) p;
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p1[0] = v >> 8;
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p1[1] = v & 0xff;
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}
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static __inline void
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cpu_to_be32wu(uint32_t *p, uint32_t v)
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{
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uint8_t *p1 = (uint8_t *) p;
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p1[0] = v >> 24;
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p1[1] = v >> 16;
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p1[2] = v >> 8;
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p1[3] = v;
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}
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#endif
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#ifdef WORDS_BIGENDIAN
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# define cpu_to_32wu cpu_to_be32wu
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#else
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# define cpu_to_32wu cpu_to_le32wu
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#endif
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#undef le_bswap
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#undef be_bswap
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#undef le_bswaps
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#undef be_bswaps
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#endif /*BSWAP_H*/
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