zydis/Zydis/ZydisUtils.cpp

/***************************************************************************************************

  Zyan Disassembler Engine
  Version 1.0

  Remarks         : Freeware, Copyright must be included

  Original Author : Florian Bernd
  Modifications   : Joel H<EFBFBD>ner

 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.

***************************************************************************************************/

#include "ZydisUtils.hpp"
#include <cassert>

namespace Zydis
{

uint64_t CalcAbsoluteTarget(const InstructionInfo& info, const OperandInfo& operand)
{
    assert((operand.type == OperandType::REL_IMMEDIATE) || 
        ((operand.type == OperandType::MEMORY) && (operand.base == Register::RIP)));
   
    uint64_t truncMask = 0xFFFFFFFFFFFFFFFFull;
    if (!(info.flags & IF_DISASSEMBLER_MODE_64)) 
    {
        truncMask >>= (64 - info.operand_mode);
    }
    uint16_t size = operand.size;
    if ((operand.type == OperandType::MEMORY) && (operand.base == Register::RIP))
    {
        size = operand.offset;
    }
    switch (size)
    {
    case 8:
        return (info.instrPointer + operand.lval.sbyte) & truncMask;
    case 16:
        {
            uint32_t delta = operand.lval.sword & truncMask;
            if ((info.instrPointer + delta) > 0xFFFF)
            {
                return (info.instrPointer&  0xF0000) + ((info.instrPointer + delta) & 0xFFFF);    
            }
            return info.instrPointer + delta;
        }
    case 32:
        return (info.instrPointer + operand.lval.sdword) & truncMask;
    default:
        assert(0);
    }
    return 0;
}

}