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ppc.cpp
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128 lines (99 loc) · 2.75 KB
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/*
Patchdiff2
Portions (C) 2010 - 2011 Nicolas Pouvesle
Portions (C) 2007 - 2009 Tenable Network Security, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License version 2 as
published by the Free Software Foundation.
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. If not, see <http://www.gnu.org/licenses/>.
*/
#include "precomp.hpp"
#include "ppc.hpp"
#include "patchdiff.hpp"
extern cpu_t patchdiff_cpu;
/*------------------------------------------------*/
/* function : ppc_is_nop */
/* arguments: unsigned char _byte */
/* description: detects if instruction is a nop */
/* (mr rA, rA) */
/*------------------------------------------------*/
bool ppc_is_nop (unsigned char _byte, ea_t ea)
{
unsigned char s, a, b, rc;
unsigned short v;
unsigned long l;
_byte = get_byte(ea) >> 2;
// or rS, rA, rB
if (_byte == 31)
{
v = get_word(ea);
s = (v >> 5) & 0x1F;
a = v & 0x1F;
if (s == a)
{
v = get_word(ea+2);
b = v >> 11;
rc = v & 1;
v = (v >> 1) & 0x3FF;
if (b == s && v == 444 && !rc)
return true;
}
}
// nop: ori 0,0,0
else if (_byte == 24)
{
l = get_long(ea);
if (l == 0x60000000)
return true;
}
return false;
}
/*------------------------------------------------*/
/* function : ppc_remove_instr */
/* arguments: unsigned char byte, ea_t ea */
/* description: Returns true is the instruction */
/* must be ignored */
/*------------------------------------------------*/
bool ppc_remove_instr(unsigned char byte, ea_t ea)
{
if (ppc_is_nop(byte, ea))
return true;
/*
// if not addi (li)
if (byte != 14)
return false;
// removes li, rD, 0 (addi rD, rA, 0 with rA == 0)
b = get_byte(ea+1) & 0x1F;
if (!b)
{
s = get_word(ea+2);
if (s == 0)
return true;
}
*/
return false;
}
/*------------------------------------------------*/
/* function : ppc_get_byte */
/* arguments: unsigned char _byte */
/* description: Returns opcode */
/*------------------------------------------------*/
unsigned char ppc_get_byte(ea_t ea)
{
unsigned char byte;
unsigned short v;
byte = get_byte(ea) >> 2;
if (byte == 31)
{
v = get_word(ea+2);
v = (v >> 1) & 0xFF;
if (v < 65) v += 65;
byte = (unsigned char)v;
}
return byte;
}