bswap.c revision 222908
1112158Sdas/* 2112158Sdas * Written by Manuel Bouyer <bouyer@netbsd.org>. 3112158Sdas * Public domain. 4112158Sdas */ 5112158Sdas 6112158Sdas#include <sys/cdefs.h> 7112158Sdas__FBSDID("$FreeBSD: head/lib/libstand/bswap.c 222908 2011-06-10 01:13:15Z rodrigc $"); 8112158Sdas 9112158Sdas#if defined(LIBC_SCCS) && !defined(lint) 10112158Sdasstatic char *rcsid = "$NetBSD: bswap32.c,v 1.1 1997/10/09 15:42:33 bouyer Exp $"; 11112158Sdasstatic char *rcsid = "$NetBSD: bswap64.c,v 1.3 2009/03/16 05:59:21 cegger Exp $"; 12112158Sdas#endif 13112158Sdas 14112158Sdas#include <sys/types.h> 15112158Sdas 16112158Sdas#undef bswap32 17112158Sdas#undef bswap64 18112158Sdas 19112158Sdasu_int32_t bswap32(u_int32_t x); 20112158Sdasu_int64_t bswap64(u_int64_t x); 21112158Sdas 22112158Sdasu_int32_t 23112158Sdasbswap32(u_int32_t x) 24112158Sdas{ 25112158Sdas return ((x << 24) & 0xff000000 ) | 26112158Sdas ((x << 8) & 0x00ff0000 ) | 27112158Sdas ((x >> 8) & 0x0000ff00 ) | 28112158Sdas ((x >> 24) & 0x000000ff ); 29165743Sdas} 30165743Sdas 31112158Sdasu_int64_t 32112158Sdasbswap64(u_int64_t x) 33112158Sdas{ 34112158Sdas#ifdef _LP64 35112158Sdas /* 36112158Sdas * Assume we have wide enough registers to do it without touching 37112158Sdas * memory. 38112158Sdas */ 39112158Sdas return ( (x << 56) & 0xff00000000000000UL ) | 40112158Sdas ( (x << 40) & 0x00ff000000000000UL ) | 41112158Sdas ( (x << 24) & 0x0000ff0000000000UL ) | 42112158Sdas ( (x << 8) & 0x000000ff00000000UL ) | 43112158Sdas ( (x >> 8) & 0x00000000ff000000UL ) | 44112158Sdas ( (x >> 24) & 0x0000000000ff0000UL ) | 45112158Sdas ( (x >> 40) & 0x000000000000ff00UL ) | 46112158Sdas ( (x >> 56) & 0x00000000000000ffUL ); 47112158Sdas#else 48112158Sdas /* 49112158Sdas * Split the operation in two 32bit steps. 50112158Sdas */ 51112158Sdas u_int32_t tl, th; 52112158Sdas 53112158Sdas th = bswap32((u_int32_t)(x & 0x00000000ffffffffULL)); 54112158Sdas tl = bswap32((u_int32_t)((x >> 32) & 0x00000000ffffffffULL)); 55112158Sdas return ((u_int64_t)th << 32) | tl; 56112158Sdas#endif 57112158Sdas} 58112158Sdas