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_sar(T v, int count)

{

    uint16_t flags = 0;

    T sign_bit = 0x80 << (8 * (sizeof(T) - 1));

    bool is_negative = !!(v & sign_bit);

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

        flags &= ~CF;

        if (v & 0x1)

            flags |= CF;

        v >>= 1;

        if (is_negative)

            v |= sign_bit;

    }

    if (!v)

        flags |= ZF;

    if (!__builtin_parity(v & 0xff))

        flags |= PF;

    if (v & sign_bit)

        flags |= SF;

    return std::make_pair(flags, v);

}

// sar r/m, N

void EmulatorPimpl::sarc0()

{

    auto v = read_data<uint8_t>();

    auto count = fetch_byte();

    uint16_t flags;

    if (!(count & 0x1f))

        return;

    std::tie(flags, v) = do_sar(v, count & 0x1f);

    write_data<uint8_t>(v);

    registers->set_flags(flags, CF | ZF | PF | SF);

}

// sar r/m, 1

void EmulatorPimpl::sarc1()

{

    auto v = read_data<uint16_t>();

    auto count = fetch_byte();

    uint16_t flags;

    if (!(count & 0x1f))

        return;

    std::tie(flags, v) = do_sar(v, count & 0x1f);

    write_data<uint16_t>(v);

    registers->set_flags(flags, CF | ZF | PF | SF);

}

// sar r/m, 1

void EmulatorPimpl::sard0()

{

    auto v = read_data<uint8_t>();

    uint16_t flags;

    std::tie(flags, v) = do_sar(v, 1);

    write_data<uint8_t>(v);

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

}

// sar r/m, 1

void EmulatorPimpl::sard1()

{

    auto v = read_data<uint16_t>();

    uint16_t flags;

    std::tie(flags, v) = do_sar(v, 1);

    write_data<uint16_t>(v);

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

}

// sar r/m, N

void EmulatorPimpl::sard2()

{

    auto v = read_data<uint8_t>();

    uint16_t flags;

    if (!registers->get(CL))

        return;

    std::tie(flags, v) = do_sar(v, registers->get(CL));

    write_data<uint8_t>(v);

    registers->set_flags(flags, CF | ZF | PF | SF);

}

// sar r/m, N

void EmulatorPimpl::sard3()

{

    auto v = read_data<uint16_t>();

    uint16_t flags;

    if (!registers->get(CL))

        return;

    std::tie(flags, v) = do_sar(v, registers->get(CL));

    write_data<uint16_t>(v);

    registers->set_flags(flags, CF | ZF | PF | SF);

}