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// SPDX-License-Identifier: GPL-2.0+
/*******************************************************************************
* QtMips - MIPS 32-bit Architecture Subset Simulator
*
* Implemented to support following courses:
*
* B35APO - Computer Architectures
* https://cw.fel.cvut.cz/wiki/courses/b35apo
*
* B4M35PAP - Advanced Computer Architectures
* https://cw.fel.cvut.cz/wiki/courses/b4m35pap/start
*
* Copyright (c) 2017-2019 Karel Koci<cynerd@email.cz>
* Copyright (c) 2019 Pavel Pisa <pisa@cmp.felk.cvut.cz>
*
* Faculty of Electrical Engineering (http://www.fel.cvut.cz)
* Czech Technical University (http://www.cvut.cz/)
*
* 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., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
******************************************************************************/
#include "registers.h"
#include "qtmipsexception.h"
using namespace machine;
// TODO should this be configurable?
//////////////////////////////////////////////////////////////////////////////
/// Program counter initial value
#define PC_INIT 0x80020000
#define SP_INIT 0xbfffff00
//////////////////////////////////////////////////////////////////////////////
Registers::Registers() : QObject() {
reset();
}
Registers::Registers(const Registers &orig) : QObject() {
this->pc = orig.read_pc();
for (std::uint8_t i = 0; i < 31; i++)
this->gp[i] = orig.read_gp(i + 1);
this->lo = orig.read_hi_lo(false);
this->hi = orig.read_hi_lo(true);
}
std::uint32_t Registers::read_pc() const {
return this->pc;
}
std::uint32_t Registers::pc_inc() {
this->pc += 4;
emit pc_update(this->pc);
return this->pc;
}
std::uint32_t Registers::pc_jmp(std::int32_t offset) {
if (offset % 4)
throw QTMIPS_EXCEPTION(UnalignedJump, "Trying to jump by unaligned offset", QString::number(offset, 16));
this->pc += offset;
emit pc_update(this->pc);
return this->pc;
}
void Registers::pc_abs_jmp(std::uint32_t address) {
if (address % 4)
throw QTMIPS_EXCEPTION(UnalignedJump, "Trying to jump to unaligned address", QString::number(address, 16));
this->pc = address;
emit pc_update(this->pc);
}
void Registers::pc_abs_jmp_28(std::uint32_t address) {
this->pc_abs_jmp((pc & 0xF0000000) | (address & 0x0FFFFFFF));
}
std::uint32_t Registers::read_gp(std::uint8_t i) const {
std::uint32_t value;
SANITY_ASSERT(i < 32, QString("Trying to read from register ") + QString(i));
if (!i) // $0 always reads as 0
return 0;
value = this->gp[i - 1];
emit gp_read(i, value);
return value;
}
void Registers::write_gp(std::uint8_t i, std::uint32_t value) {
SANITY_ASSERT(i < 32, QString("Trying to write to register ") + QString(i));
if (i == 0) // Skip write to $0
return;
this->gp[i - 1] = value;
emit gp_update(i, value);
}
std::uint32_t Registers::read_hi_lo(bool is_hi) const {
std::uint32_t value;
if (is_hi)
value = hi;
else
value = lo;
emit hi_lo_read(is_hi, value);
return value;
}
void Registers::write_hi_lo(bool is_hi, std::uint32_t value) {
if (is_hi)
hi = value;
else
lo = value;
emit hi_lo_update(is_hi, value);
}
bool Registers::operator==(const Registers &c) const {
if (read_pc() != c.read_pc())
return false;
for (std::uint8_t i = 0; i < 31; i++)
if (read_gp(i) != c.read_gp(i))
return false;
if (read_hi_lo(false) != c.read_hi_lo(false))
return false;
if (read_hi_lo(true) != c.read_hi_lo(true))
return false;
return true;
}
bool Registers::operator!=(const Registers &c) const {
return ! this->operator==(c);
}
void Registers::reset() {
pc_abs_jmp(PC_INIT); // Initialize to beginning program section
for (int i = 1; i < 32; i++)
write_gp(i, 0);
write_gp(29, SP_INIT); // initialize to safe RAM area - corresponds to Linux
write_hi_lo(false, 0);
write_hi_lo(true, 0);
}
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