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/* bufhelp.h - Some buffer manipulation helpers
* Copyright © 2012 Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser general Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#ifndef G10_BUFHELP_H
#define G10_BUFHELP_H
#ifdef HAVE_STDINT_H
# include <stdint.h> /* uintptr_t */
#elif defined(HAVE_INTTYPES_H)
# include <inttypes.h>
#else
/* In this case, uintptr_t is provided by config.h. */
#endif
#if defined(__i386__) || defined(__x86_64__)
/* These architechtures are able of unaligned memory accesses and can
handle those fast.
*/
# define BUFHELP_FAST_UNALIGNED_ACCESS 1
#endif
/* Optimized function for buffer xoring */
static inline void
buf_xor(void *_dst, const void *_src1, const void *_src2, size_t len)
{
byte *dst = _dst;
const byte *src1 = _src1;
const byte *src2 = _src2;
uintptr_t *ldst;
const uintptr_t *lsrc1, *lsrc2;
#ifndef BUFHELP_FAST_UNALIGNED_ACCESS
const unsigned int longmask = sizeof(uintptr_t) - 1;
/* Skip fast processing if alignment of buffers do not match. */
if ((((uintptr_t)dst ^ (uintptr_t)src1) |
((uintptr_t)dst ^ (uintptr_t)src2)) & longmask)
goto do_bytes;
/* Handle unaligned head. */
for (; len && ((uintptr_t)dst & longmask); len--)
*dst++ = *src1++ ^ *src2++;
#endif
ldst = (uintptr_t *)dst;
lsrc1 = (const uintptr_t *)src1;
lsrc2 = (const uintptr_t *)src2;
for (; len >= sizeof(uintptr_t); len -= sizeof(uintptr_t))
*ldst++ = *lsrc1++ ^ *lsrc2++;
dst = (byte *)ldst;
src1 = (const byte *)lsrc1;
src2 = (const byte *)lsrc2;
#ifndef BUFHELP_FAST_UNALIGNED_ACCESS
do_bytes:
#endif
/* Handle tail. */
for (; len; len--)
*dst++ = *src1++ ^ *src2++;
}
/* Optimized function for buffer xoring with two destination buffers. Used
mainly by CFB mode encryption. */
static inline void
buf_xor_2dst(void *_dst1, void *_dst2, const void *_src, size_t len)
{
byte *dst1 = _dst1;
byte *dst2 = _dst2;
const byte *src = _src;
uintptr_t *ldst1, *ldst2;
const uintptr_t *lsrc;
#ifndef BUFHELP_FAST_UNALIGNED_ACCESS
const unsigned int longmask = sizeof(uintptr_t) - 1;
/* Skip fast processing if alignment of buffers do not match. */
if ((((uintptr_t)src ^ (uintptr_t)dst1) |
((uintptr_t)src ^ (uintptr_t)dst2)) & longmask)
goto do_bytes;
/* Handle unaligned head. */
for (; len && ((uintptr_t)src & longmask); len--)
*dst1++ = (*dst2++ ^= *src++);
#endif
ldst1 = (uintptr_t *)dst1;
ldst2 = (uintptr_t *)dst2;
lsrc = (const uintptr_t *)src;
for (; len >= sizeof(uintptr_t); len -= sizeof(uintptr_t))
*ldst1++ = (*ldst2++ ^= *lsrc++);
dst1 = (byte *)ldst1;
dst2 = (byte *)ldst2;
src = (const byte *)lsrc;
#ifndef BUFHELP_FAST_UNALIGNED_ACCESS
do_bytes:
#endif
/* Handle tail. */
for (; len; len--)
*dst1++ = (*dst2++ ^= *src++);
}
/* Optimized function for combined buffer xoring and copying. Used by mainly
CFB mode decryption. */
static inline void
buf_xor_n_copy(void *_dst_xor, void *_srcdst_cpy, const void *_src, size_t len)
{
byte *dst_xor = _dst_xor;
byte *srcdst_cpy = _srcdst_cpy;
byte temp;
const byte *src = _src;
uintptr_t *ldst_xor, *lsrcdst_cpy;
const uintptr_t *lsrc;
uintptr_t ltemp;
#ifndef BUFHELP_FAST_UNALIGNED_ACCESS
const unsigned int longmask = sizeof(uintptr_t) - 1;
/* Skip fast processing if alignment of buffers do not match. */
if ((((uintptr_t)src ^ (uintptr_t)dst_xor) |
((uintptr_t)src ^ (uintptr_t)srcdst_cpy)) & longmask)
goto do_bytes;
/* Handle unaligned head. */
for (; len && ((uintptr_t)src & longmask); len--)
{
temp = *src++;
*dst_xor++ = *srcdst_cpy ^ temp;
*srcdst_cpy++ = temp;
}
#endif
ldst_xor = (uintptr_t *)dst_xor;
lsrcdst_cpy = (uintptr_t *)srcdst_cpy;
lsrc = (const uintptr_t *)src;
for (; len >= sizeof(uintptr_t); len -= sizeof(uintptr_t))
{
ltemp = *lsrc++;
*ldst_xor++ = *lsrcdst_cpy ^ ltemp;
*lsrcdst_cpy++ = ltemp;
}
dst_xor = (byte *)ldst_xor;
srcdst_cpy = (byte *)lsrcdst_cpy;
src = (const byte *)lsrc;
#ifndef BUFHELP_FAST_UNALIGNED_ACCESS
do_bytes:
#endif
/* Handle tail. */
for (; len; len--)
{
temp = *src++;
*dst_xor++ = *srcdst_cpy ^ temp;
*srcdst_cpy++ = temp;
}
}
#endif /*G10_BITHELP_H*/
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