// 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/>.

task do_shr;
    output [31:0] out;
    input is_8_bit;
    input [15:0] a;
    input [4:0] shift_count;
    input [15:0] flags_in;
    output [15:0] flags_out;
    output busy;
    input multibit_shift;

    begin
        flags_out = flags_in;
        out = {11'b0, shift_count, a};

        if (|shift_count || !multibit_shift) begin
            {out[15:0], flags_out[CF_IDX]} = {a, 1'b0} >> 1'b1;
            shift_flags(flags_out, is_8_bit, out[15:0], a);
            if (is_8_bit)
                flags_out[OF_IDX] = a[7] ^ out[7];
            else
                flags_out[OF_IDX] = a[15] ^ out[15];

            out[31:16] = {11'b0, shift_count - 1'b1};
        end

        busy = multibit_shift && |out[20:16];
    end
endtask