/* sw.h -- swaptrick filter

   This file is part of the UPX executable compressor.

   Copyright (C) 1996-2020 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1996-2020 Laszlo Molnar
   All Rights Reserved.

   UPX and the UCL library are free software; you can redistribute them
   and/or modify them under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of
   the License, or (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; see the file COPYING.
   If not, write to the Free Software Foundation, Inc.,
   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

   Markus F.X.J. Oberhumer              Laszlo Molnar
   <markus@oberhumer.com>               <ezerotven+github@gmail.com>
 */



/*************************************************************************
// 16-bit swaptrick ("naive")
**************************************************************************/

#define SW16(f, cond, get, set) \
    upx_byte *b = f->buf; \
    upx_byte *b_end = b + f->buf_len - 3; \
    do { \
        if (cond) \
        { \
            b += 1; \
            unsigned a = (unsigned) (b - f->buf); \
            f->lastcall = a; \
            set(b, get(b)); \
            f->calls++; \
            b += 2 - 1; \
        } \
    } while (++b < b_end); \
    if (f->lastcall) f->lastcall += 2; \
    return 0;


// filter
static int f_sw16_e8(Filter *f)
{
    SW16(f, (*b == 0xe8), get_le16, set_be16)
}

static int f_sw16_e9(Filter *f)
{
    SW16(f, (*b == 0xe9), get_le16, set_be16)
}

static int f_sw16_e8e9(Filter *f)
{
    SW16(f, (*b == 0xe8 || *b == 0xe9), get_le16, set_be16)
}


// unfilter
static int u_sw16_e8(Filter *f)
{
    SW16(f, (*b == 0xe8), get_be16, set_le16)
}

static int u_sw16_e9(Filter *f)
{
    SW16(f, (*b == 0xe9), get_be16, set_le16)
}

static int u_sw16_e8e9(Filter *f)
{
    SW16(f, (*b == 0xe8 || *b == 0xe9), get_be16, set_le16)
}


// scan
static int s_sw16_e8(Filter *f)
{
    SW16(f, (*b == 0xe8), get_le16, set_dummy)
}

static int s_sw16_e9(Filter *f)
{
    SW16(f, (*b == 0xe9), get_le16, set_dummy)
}

static int s_sw16_e8e9(Filter *f)
{
    SW16(f, (*b == 0xe8 || *b == 0xe9), get_le16, set_dummy)
}


#undef SW16




/*************************************************************************
// 32-bit swaptrick ("naive")
**************************************************************************/

#define SW32(f, cond, get, set) \
    upx_byte *b = f->buf; \
    upx_byte *b_end = b + f->buf_len - 5; \
    do { \
        if (cond) \
        { \
            b += 1; \
            unsigned a = (unsigned) (b - f->buf); \
            f->lastcall = a; \
            set(b, get(b)); \
            f->calls++; \
            b += 4 - 1; \
        } \
    } while (++b < b_end); \
    if (f->lastcall) f->lastcall += 4; \
    return 0;


// filter
static int f_sw32_e8(Filter *f)
{
    SW32(f, (*b == 0xe8), get_le32, set_be32)
}

static int f_sw32_e9(Filter *f)
{
    SW32(f, (*b == 0xe9), get_le32, set_be32)
}

static int f_sw32_e8e9(Filter *f)
{
    SW32(f, (*b == 0xe8 || *b == 0xe9), get_le32, set_be32)
}


// unfilter
static int u_sw32_e8(Filter *f)
{
    SW32(f, (*b == 0xe8), get_be32, set_le32)
}

static int u_sw32_e9(Filter *f)
{
    SW32(f, (*b == 0xe9), get_be32, set_le32)
}

static int u_sw32_e8e9(Filter *f)
{
    SW32(f, (*b == 0xe8 || *b == 0xe9), get_be32, set_le32)
}


// scan
static int s_sw32_e8(Filter *f)
{
    SW32(f, (*b == 0xe8), get_le32, set_dummy)
}

static int s_sw32_e9(Filter *f)
{
    SW32(f, (*b == 0xe9), get_le32, set_dummy)
}

static int s_sw32_e8e9(Filter *f)
{
    SW32(f, (*b == 0xe8 || *b == 0xe9), get_le32, set_dummy)
}


#undef SW32

/* vim:set ts=4 sw=4 et: */
