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Filter for lru recoding of "call trick" destinations.
filteri.cpp filter/ctjor.h committer: jreiser <jreiser> 978670287 +0000
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John Reiser
parent
38ab492030
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5b97d3ee09
273
src/filter/ctjor.h
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273
src/filter/ctjor.h
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@ -0,0 +1,273 @@
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/* ctjo.h -- filter CTO implementation
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This file is part of the UPX executable compressor.
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Copyright (C) 1996-2001 Markus Franz Xaver Johannes Oberhumer
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Copyright (C) 1996-2001 Laszlo Molnar
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Copyright (C) 2000-2001 John F. Reiser
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All Rights Reserved.
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UPX and the UCL library are free software; you can redistribute them
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and/or modify them under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; see the file COPYING.
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If not, write to the Free Software Foundation, Inc.,
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59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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Markus F.X.J. Oberhumer Laszlo Molnar John F. Reiser
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markus@oberhumer.com ml1050@cdata.tvnet.hu jreiser@BitWagon.com
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*/
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/*************************************************************************
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//
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**************************************************************************/
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#ifdef U //{
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static int const N_LRU = 1024; // does not have to be a power of 2
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static unsigned lru[N_LRU];
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static int hand;
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#endif //}
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static int F(Filter *f)
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{
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#ifdef U
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// filter
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upx_byte *b = f->buf;
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const unsigned addvalue = f->addvalue;
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hand = 0;
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memset(&lru[0], 0, sizeof(lru));
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#else
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// scan
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const upx_byte *b = f->buf;
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#endif
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const unsigned size = f->buf_len;
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unsigned ic, jc, kc;
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unsigned cto;
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unsigned char cto8;
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unsigned calls = 0, noncalls = 0, noncalls2 = 0;
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unsigned lastnoncall = size, lastcall = 0;
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// FIXME: We must fit into 8MB because we steal one bit.
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// find a 16MB large empty address space
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if (f->forced_cto >= 0 && f->forced_cto <= 255)
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cto8 = (unsigned char) f->forced_cto;
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else
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{
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unsigned char buf[256];
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memset(buf,0,256);
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#if 1
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for (ic = 0; ic < size - 5; ic++)
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if (CONDF(b,ic,lastcall) && get_le32(b+ic+1)+ic+1 >= size)
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{
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buf[b[ic+1]] |= 1;
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}
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#else
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{
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int i = size - 6;
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do {
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if (CONDF(b,i,lastcall) && get_le32(b+i+1)+i+1 >= size)
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buf[b[i+1]] |= 1;
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} while (--i >= 0);
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}
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#endif
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ic = 256;
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if (f->preferred_ctos)
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{
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for (const int *pc = f->preferred_ctos; *pc >= 0; pc++)
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{
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if (buf[*pc & 255] == 0)
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{
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ic = *pc & 255;
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break;
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}
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}
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}
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#if 0
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// just a test to see if certain ctos would improve compression
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if (ic >= 256)
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for (ic = 0; ic < 256; ic += 16)
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if (buf[ic] == 0)
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break;
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#endif
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if (ic >= 256)
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for (ic = 0; ic < 256; ic++)
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if (buf[ic] == 0)
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break;
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if (ic >= 256)
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//throwCantPack("call trick problem");
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return -1;
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cto8 = (unsigned char) ic;
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}
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cto = (unsigned)cto8 << 24;
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for (ic = 0; ic < size - 5; ic++)
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{
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if (!CONDF(b,ic,lastcall))
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continue;
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jc = get_le32(b+ic+1)+ic+1;
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// try to detect 'real' calls only
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if (jc < size)
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{
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#ifdef U
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if (COND2(b,lastcall,ic,ic-1,ic)) { // 6-byte Jcc <disp32>
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// Prefix 0x0f is constant, but opcode condition 0x80..0x8f
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// varies. Because we store the destination (or its lru index)
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// in be32 big endian format, the low-addressed bytes
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// will tend to be constant. Swap prefix and opcode
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// so that constants are together for better compression.
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unsigned char const t =
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b[ic-1];
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b[ic-1] = b[ic];
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b[ic] = t;
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}
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jc += addvalue;
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// FIXME [?]: Extend to 8 bytes if "ADD ESP, byte 4*n" follows CALL.
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// This will require two related cto's (consecutive, or otherwise).
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{
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// Recode the destination: narrower lru indices
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// should compress better than wider addresses.
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int k;
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for (k = 0; k < N_LRU; ++k) {
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int kh = hand + k;
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if (N_LRU <= kh) {
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kh -= N_LRU;
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}
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if (lru[kh] == jc) { // destination was seen recently
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set_be32(b+ic+1,((k<<1)|0)+cto);
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break;
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}
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}
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if (k == N_LRU) { // loop failed; jc is not in lru[]
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set_be32(b+ic+1,((jc<<1)|1)+cto);
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}
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}
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// Adaptively remember recent destinations.
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if (0 > --hand) {
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hand = N_LRU -1;
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}
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lru[hand] = jc;
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#endif
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if (ic - lastnoncall < 5)
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{
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// check the last 4 bytes before this call
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for (kc = 4; kc; kc--)
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if (CONDF(b,ic-kc,lastcall) && b[ic-kc+1] == cto8)
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break;
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if (kc)
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{
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#ifdef U
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// restore original
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if (COND2(b,lastcall,ic,ic,ic-1)) {
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// Unswap prefix and opcode for 6-byte Jcc <disp32>
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unsigned char const t =
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b[ic-1];
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b[ic-1] = b[ic];
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b[ic] = t;
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}
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set_le32(b+ic+1,jc-ic-1);
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#endif
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if (b[ic+1] == cto8)
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return 1; // fail - buffer not restored
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lastnoncall = ic;
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noncalls2++;
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continue;
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}
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}
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calls++;
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ic += 4;
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lastcall = ic+1;
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}
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else
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{
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assert(b[ic+1] != cto8); // this should not happen
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lastnoncall = ic;
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noncalls++;
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}
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}
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f->cto = cto8;
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f->calls = calls;
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f->noncalls = noncalls;
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f->lastcall = lastcall;
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#ifdef TESTING
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printf("\ncalls=%d noncalls=%d noncalls2=%d text_size=%x calltrickoffset=%x\n",calls,noncalls,noncalls2,size,cto);
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#endif
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return 0;
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}
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#ifdef U
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static int U(Filter *f)
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{
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upx_byte *b = f->buf;
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const unsigned size5 = f->buf_len - 5;
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const unsigned addvalue = f->addvalue;
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const unsigned cto = f->cto << 24;
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unsigned lastcall = 0;
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unsigned ic, jc;
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hand = 0;
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for (ic = 0; ic < size5; ic++)
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if (CONDU(b,ic,lastcall))
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{
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jc = get_be32(b+ic+1) - cto;
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if (b[ic+1] == f->cto)
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{
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if (1&jc) { // 1st time at this destination
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jc = (jc >> 1) - addvalue;
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}
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else { // not 1st time at this destination
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jc = (jc >> 1) - addvalue;
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int kh = jc + hand;
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if (N_LRU <= kh) {
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kh -= N_LRU;
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}
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jc = lru[kh];
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}
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if (0 > --hand) {
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hand = N_LRU -1;
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}
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lru[hand] = jc;
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set_le32(b+ic+1,jc-ic-1);
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if (COND2(b,lastcall,ic,ic,ic-1)) {
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// Unswap prefix and opcode for 6-byte Jcc <disp32>
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unsigned char const t =
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b[ic-1];
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b[ic-1] = b[ic];
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b[ic] = t;
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}
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f->calls++;
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ic += 4;
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f->lastcall = lastcall = ic+1;
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}
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else
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f->noncalls++;
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}
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return 0;
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}
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#endif
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#undef F
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#undef U
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/*
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vi:ts=4:et:nowrap
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*/
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@ -86,6 +86,28 @@
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#undef COND
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/*************************************************************************
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//
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**************************************************************************/
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#define COND1(b,x) (b[x] == 0xe8 || b[x] == 0xe9)
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#define COND2(b,lastcall,x,y,z) \
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(lastcall!=(x) && 0xf==b[y] && 0x80<=b[z] && b[z]<=0x8f)
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#define CONDF(b,x,lastcall) (COND1(b,x) || COND2(b,lastcall,x,(x)-1, x ))
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#define CONDU(b,x,lastcall) (COND1(b,x) || COND2(b,lastcall,x, x ,(x)-1))
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#define F f_ctjor32_e8e9_bswap_le
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#define U u_ctjor32_e8e9_bswap_le
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#include "filter/ctjor.h"
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#define F s_ctjor32_e8e9_bswap_le
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#include "filter/ctjor.h"
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#undef CONDU
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#undef CONDF
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#undef COND2
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#undef COND1
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/*************************************************************************
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// database for use in class Filter
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**************************************************************************/
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@ -133,6 +155,9 @@ const FilterImp::FilterEntry FilterImp::filters[] = {
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{ 0x26, 6, 0x00ffffff, f_cto32_e8e9_bswap_le, u_cto32_e8e9_bswap_le, s_cto32_e8e9_bswap_le },
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// 32-bit cto calltrick + jmp
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{ 0x36, 6, 0x00ffffff, f_ctjo32_e8e9_bswap_le, u_ctjo32_e8e9_bswap_le, s_ctjo32_e8e9_bswap_le },
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// 32-bit ctor calltrick with relative renumbering + jmp
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{ 0x80, 8, 0x00ffffff, f_ctjor32_e8e9_bswap_le, u_ctjor32_e8e9_bswap_le, s_ctjor32_e8e9_bswap_le },
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};
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const int FilterImp::n_filters = HIGH(filters);
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