#include "registers.h"
#include "qtmipsexception.h"

using namespace machine;

// TODO should this be configurable?
//////////////////////////////////////////////////////////////////////////////
/// Program counter initial value
#define PC_INIT 0x80020000
//////////////////////////////////////////////////////////////////////////////

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 {
    SANITY_ASSERT(i < 32, QString("Trying to read from register ") + QString(i));
    if (!i) // $0 always reads as 0
        return 0;
    return this->gp[i - 1];
}

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;
    emit gp_update(i, value);
    this->gp[i - 1] = value;
}

std::uint32_t Registers::read_hi_lo(bool is_hi) const {
    if (is_hi)
        return hi;
    else
        return lo;
}

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_hi_lo(false, 0);
    write_hi_lo(true, 0);
}