bswap64.c revision 1.1
11.1Schristos/* $NetBSD: bswap64.c,v 1.1 2005/12/20 19:28:51 christos Exp $ */ 21.1Schristos 31.1Schristos/* 41.1Schristos * Written by Manuel Bouyer <bouyer@NetBSD.org>. 51.1Schristos * Public domain. 61.1Schristos */ 71.1Schristos 81.1Schristos#include <sys/cdefs.h> 91.1Schristos#if defined(LIBC_SCCS) && !defined(lint) 101.1Schristos__RCSID("$NetBSD: bswap64.c,v 1.1 2005/12/20 19:28:51 christos Exp $"); 111.1Schristos#endif /* LIBC_SCCS and not lint */ 121.1Schristos 131.1Schristos#include <sys/types.h> 141.1Schristos#include <machine/bswap.h> 151.1Schristos 161.1Schristos#undef bswap64 171.1Schristos 181.1Schristosu_int64_t 191.1Schristosbswap64(x) 201.1Schristos u_int64_t x; 211.1Schristos{ 221.1Schristos#ifdef _LP64 231.1Schristos /* 241.1Schristos * Assume we have wide enough registers to do it without touching 251.1Schristos * memory. 261.1Schristos */ 271.1Schristos return ( (x << 56) & 0xff00000000000000UL ) | 281.1Schristos ( (x << 40) & 0x00ff000000000000UL ) | 291.1Schristos ( (x << 24) & 0x0000ff0000000000UL ) | 301.1Schristos ( (x << 8) & 0x000000ff00000000UL ) | 311.1Schristos ( (x >> 8) & 0x00000000ff000000UL ) | 321.1Schristos ( (x >> 24) & 0x0000000000ff0000UL ) | 331.1Schristos ( (x >> 40) & 0x000000000000ff00UL ) | 341.1Schristos ( (x >> 56) & 0x00000000000000ffUL ); 351.1Schristos#else 361.1Schristos /* 371.1Schristos * Split the operation in two 32bit steps. 381.1Schristos */ 391.1Schristos u_int32_t tl, th; 401.1Schristos 411.1Schristos th = bswap32((u_int32_t)(x & 0x00000000ffffffffULL)); 421.1Schristos tl = bswap32((u_int32_t)((x >> 32) & 0x00000000ffffffffULL)); 431.1Schristos return ((u_int64_t)th << 32) | tl; 441.1Schristos#endif 451.1Schristos} 46