jump_instruction.cpp

浙江大学的悟空嵌入式系统模拟器

/*
*  Copyright (c) 2005 Zhejiang University, P.R.China
*
*  This program is free software; you can redistribute it and/or modify
*  it 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; if not, write to the Free Software
*  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/ 

//=============================================================================
/**
*  \file    ARM/Jump_Instruction.cpp
*
*  $Id: Jump_Instruction.cpp,v 1.3 2005/06/08 07:40:45 qilj Exp $
*
*  \author  Lingjie Qi <[e-mail]> 
*/
//=============================================================================

#include "./Jump_Instruction.h"

namespace ARM {

	DEFINE_SINGLETON(Jump_Instruction)

		s32 Jump_Instruction::signed_immed_24(Core::Instruction_Unit & binary)
	{
		if(binary & 0x00800000)
		{
			return (s32)(binary | 0xFF000000 );
		}
		else
		{
			return (s32)(  binary & 0x00ffffff );
		}
	}

	void Jump_Instruction::execute(Core::Instruction_Unit  binary)
	{
		Core::Binary_32Bit bits(binary);
		u32 opcode = bits.convert_to_int(24,27);
		u32 val, Rm, operand = (u32)bits.convert_to_int(0,23);

		switch(opcode)
		{
			//! This is a B instruction
		case  BINARY4(1010):
			get_cpu()->read_register(15, val);
			val = val + 4 + (signed_immed_24(operand)<<2);
			get_cpu()->write_register( 15, val );
			break;

			//! This is a BL instruction
		case  BINARY4(1011):
			get_cpu()->read_register(15, val);
			get_cpu()->write_register( 14, val );
			val = val + 4 + (signed_immed_24(operand)<<2);
			get_cpu()->write_register( 15, val );
			break;

			//! This is a BX instruction
		case  BINARY4(0001):
			Core::u32 Rm_index = bits.convert_to_int(0,3);
			get_cpu()->read_register(Rm_index, Rm);
			val = Rm & 0x1;
			assign( get_cpu()->get_cpsr(), 5, 5, val);
			val = Rm & 0xFFFFFFFE;
			get_cpu()->write_register( 15, val );
		}
		return ;
	}

} //namespace