45 lines
1.1 KiB
C
45 lines
1.1 KiB
C
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/* $NetBSD: bswap64.c,v 1.3 2009/03/16 05:59:21 cegger Exp $ */
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/*
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* Written by Manuel Bouyer <bouyer@NetBSD.org>.
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* Public domain.
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*/
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#include <sys/cdefs.h>
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#if defined(LIBC_SCCS) && !defined(lint)
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__RCSID("$NetBSD: bswap64.c,v 1.3 2009/03/16 05:59:21 cegger Exp $");
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#endif /* LIBC_SCCS and not lint */
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#include <sys/types.h>
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#include <machine/bswap.h>
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#undef bswap64
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uint64_t
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bswap64(uint64_t x)
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{
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#ifdef _LP64
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/*
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* Assume we have wide enough registers to do it without touching
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* memory.
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*/
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return ( (x << 56) & 0xff00000000000000UL ) |
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( (x << 40) & 0x00ff000000000000UL ) |
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( (x << 24) & 0x0000ff0000000000UL ) |
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( (x << 8) & 0x000000ff00000000UL ) |
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( (x >> 8) & 0x00000000ff000000UL ) |
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( (x >> 24) & 0x0000000000ff0000UL ) |
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( (x >> 40) & 0x000000000000ff00UL ) |
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( (x >> 56) & 0x00000000000000ffUL );
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#else
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/*
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* Split the operation in two 32bit steps.
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*/
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uint32_t tl, th;
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th = bswap32((uint32_t)(x & 0x00000000ffffffffULL));
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tl = bswap32((uint32_t)((x >> 32) & 0x00000000ffffffffULL));
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return ((uint64_t)th << 32) | tl;
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#endif
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}
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