progs/perftest.c: Use from Glibc syscall numbers.

[catacomb] / symm / ocb.h

/* -*-c-*-
 *
 * Common definitions for OCB and related modes
 *
 * (c) 2018 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------*
 *
 * This file is part of Catacomb.
 *
 * Catacomb is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Library General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Catacomb 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with Catacomb.  If not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
 * USA.
 */

#ifndef CATACOMB_OCB_H
#define CATACOMB_OCB_H

#ifdef __cplusplus
  extern "C" {
#endif

/*----- Header files ------------------------------------------------------*/

#include <stddef.h>

#include <mLib/bits.h>
#include <mLib/compiler.h>

/*----- Constants ---------------------------------------------------------*/

/* The number of offsets to maintain.  Rather than calculate and store all
 * possible offset values in advance, or calculate new ones on demand (and
 * have to allocate space for them), we calculate a number in advance, and
 * determine any others every time they're needed.  If we calculate the first
 * %$n$% offsets only, then we spend %$i - n + 1$% time calculating offset
 * %$L_i$% when %$i \ge n$%.  But the offset %$L_i$% is used only for a
 * %$2^{-i-1}$% fraction of the blocks.  Summing up this geometric series
 * shows us that we add only a small constant overhead, and save storage
 * space for many offsets.
 */
#define OCB_NCALC 16
#define OCB_CALCMASK ((1ul << OCB_NCALC) - 1)

/*----- Functions provided ------------------------------------------------*/

/* --- @ocb_ctz@, @ocb_ctzl@ --- *
 *
 * Arguments:	@unsigned i@ or @unsigned long i@ = operand, assumed nonzero
 *
 * Returns:	The number of trailing zero bits in @i@, or nonsense if
 *		%$i = 0$%.
 */

extern unsigned ocb_ctz(unsigned /*i*/);
extern unsigned ocb_ctzl(unsigned long /*i*/);

#if GCC_VERSION_P(3, 4)
#  define OCB_CTZ(i) __builtin_ctz(i)
#  define OCB_CTZL(i) __builtin_ctzl(i)
#else
#  define OCB_CTZ(i) ocb_ctz(i)
#  define OCB_CTZL(i) ocb_ctzl(i)
#endif

/* --- @OCB_OFFSET@ --- *
 *
 * Arguments:	@PRE@ = block cipher prefix
 *		@uint32 *o@ = pointer to offset accumulator
 *		@uint32 (*l)[PRE_BLKSZ]@ = pointer to offset mask table
 *		@unsigned long i@ = block index
 *
 * Returns:	---
 *
 * Use:		Update the per-block offset for Grey-code-based OCB
 *		variants.  On entry, @o@ is assumed to hold the offset for
 *		block @i - 1@; on exit @o@ is updated to hold the offset for
 *		block @i@.
 */

#define OCB_OFFSET(PRE, o, l, i) do {					\
  uint32 (*_l)[PRE##_BLKSZ/4] = (l);					\
  uint32 *_o = (o);							\
  unsigned long _i = (i);						\
  unsigned _j;								\
									\
  if (_i&OCB_CALCMASK) {						\
    _j = OCB_CTZ(_i);							\
    BLKC_XMOVE(PRE, _o, _l[_j]);					\
  } else {								\
    uint32 _t[PRE##_BLKSZ];						\
    _j = OCB_CTZL(_i) - OCB_NCALC;					\
    BLKC_BLSHIFT(PRE, IRRED, _t, _l[OCB_NCALC - 1]);			\
    while (_j--) BLKC_BLSHIFT(PRE, IRRED, _t, _t);			\
    BLKC_XMOVE(PRE, _t, _l[_j]);					\
  }									\
} while (0)

/*----- That's all, folks -------------------------------------------------*/

#ifdef __cplusplus
  }
#endif

#endif