Subversion Repositories s80186

// Copyright Jamie Iles, 2017

//

// This file is part of s80x86.

//

// s80x86 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 3 of the License, or

// (at your option) any later version.

//

// s80x86 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 s80x86.  If not, see <http://www.gnu.org/licenses/>.

template <typename T>

std::pair<uint16_t, T> do_rcr(T v, int count, bool carry_in)

{

    uint16_t flags = carry_in ? CF : 0;

    for (int i = 0; i < (count & 0x1f); ++i) {

        bool carry_bit_set = !!(flags & CF);

        flags &= ~CF;

        T lsb = v & 1;

        v >>= 1;

        v += static_cast<T>(carry_bit_set) << ((sizeof(T) * 8) - 1);

        if (lsb)

            flags |= CF;

    }

    // 2 MSB's XOR'd == OF

    T msbs = (v >> ((sizeof(T) * 8) - 2)) & 0x3;

    if (msbs == 2 || msbs == 1)

        flags |= OF;

    return std::make_pair(flags, v);

}

// rcr r/m, N

void EmulatorPimpl::rcrc0()

{

    auto v = read_data<uint8_t>();

    auto count = fetch_byte();

    uint16_t flags;

    if (!(count & 0x1f))

        return;

    std::tie(flags, v) = do_rcr(v, count & 0x1f, registers->get_flag(CF));

    write_data<uint8_t>(v);

    registers->set_flags(flags, CF);

}

// rcr r/m, 1

void EmulatorPimpl::rcrc1()

{

    auto v = read_data<uint16_t>();

    auto count = fetch_byte();

    uint16_t flags;

    if (!(count & 0x1f))

        return;

    std::tie(flags, v) = do_rcr(v, count & 0x1f, registers->get_flag(CF));

    write_data<uint16_t>(v);

    registers->set_flags(flags, CF);

}

// rcr r/m, 1

void EmulatorPimpl::rcrd0()

{

    auto v = read_data<uint8_t>();

    uint16_t flags;

    std::tie(flags, v) = do_rcr(v, 1, registers->get_flag(CF));

    write_data<uint8_t>(v);

    registers->set_flags(flags, CF | OF);

}

// rcr r/m, 1

void EmulatorPimpl::rcrd1()

{

    auto v = read_data<uint16_t>();

    uint16_t flags;

    std::tie(flags, v) = do_rcr(v, 1, registers->get_flag(CF));

    write_data<uint16_t>(v);

    registers->set_flags(flags, CF | OF);

}

// rcr r/m, N

void EmulatorPimpl::rcrd2()

{

    auto v = read_data<uint8_t>();

    uint16_t flags;

    if (!registers->get(CL))

        return;

    std::tie(flags, v) = do_rcr(v, registers->get(CL), registers->get_flag(CF));

    write_data<uint8_t>(v);

    registers->set_flags(flags, CF);

}

// rcr r/m, N

void EmulatorPimpl::rcrd3()

{

    auto v = read_data<uint16_t>();

    uint16_t flags;

    if (!registers->get(CL))

        return;

    std::tie(flags, v) = do_rcr(v, registers->get(CL), registers->get_flag(CF));

    write_data<uint16_t>(v);

    registers->set_flags(flags, CF);

}