// 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/>.

// Multiplicand in TEMP, multiplier in MDR
mulf6_reg:
    width W8, a_sel RA, alu_op SELA, mdr_write, ra_sel AL, jmp do_mul8;
mulf6_mem:
    width W8, segment DS, mem_read, ra_sel AL, jmp do_mul8;
do_mul8:
    width W8, a_sel RA, alu_op SELA, tmp_wr_en;
    // 8-bit multiplication yields a 16-bit result so move the result into
    // TEMP to later transfer to AX as a 16-bit operation.
    width W8, a_sel MDR, b_sel TEMP, alu_op MUL, update_flags ZF OF CF,
        tmp_wr_en;
    b_sel TEMP, alu_op SELB, rd_sel_source MICROCODE_RD_SEL, rd_sel AX,
        next_instruction;

// Multiplicand in TEMP, multiplier in MDR
mulf7_reg:
    a_sel RA, alu_op SELA, mdr_write, ra_sel AX, jmp do_mul16;
mulf7_mem:
    segment DS, mem_read, ra_sel AX, jmp do_mul16;
do_mul16:
    a_sel RA, alu_op SELA, tmp_wr_en;
    a_sel MDR, b_sel TEMP, alu_op MUL, update_flags ZF OF CF,
        tmp_wr_sel Q_HIGH, tmp_wr_en, rd_sel_source MICROCODE_RD_SEL,
        rd_sel AX;
    b_sel TEMP, alu_op SELB, rd_sel_source MICROCODE_RD_SEL, rd_sel DX,
        next_instruction;

// imultiplicand in TEMP, imultiplier in MDR
imulf6_reg:
    width W8, a_sel RA, alu_op SELA, mdr_write, ra_sel AL, jmp do_imul8;
imulf6_mem:
    width W8, segment DS, mem_read, ra_sel AL, jmp do_imul8;
do_imul8:
    width W8, a_sel RA, alu_op SELA, tmp_wr_en;
    // 8-bit imultiplication yields a 16-bit result so move the result into
    // TEMP to later transfer to AX as a 16-bit operation.
    width W8, a_sel MDR, b_sel TEMP, alu_op IMUL, update_flags ZF OF CF,
        tmp_wr_en;
    b_sel TEMP, alu_op SELB, rd_sel_source MICROCODE_RD_SEL, rd_sel AX,
        next_instruction;

// imultiplicand in TEMP, imultiplier in MDR
imulf7_reg:
    a_sel RA, alu_op SELA, mdr_write, ra_sel AX, jmp do_imul16;
imulf7_mem:
    segment DS, mem_read, ra_sel AX, jmp do_imul16;
do_imul16:
    a_sel RA, alu_op SELA, tmp_wr_en;
    a_sel MDR, b_sel TEMP, alu_op IMUL, update_flags ZF OF CF,
        tmp_wr_sel Q_HIGH, tmp_wr_en, rd_sel_source MICROCODE_RD_SEL,
        rd_sel AX;
    b_sel TEMP, alu_op SELB, rd_sel_source MICROCODE_RD_SEL, rd_sel DX,
        next_instruction;

.at 0x6b;
    mar_write, mar_wr_sel EA, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem imul6b_reg;
.auto_address;
imul6b_reg:
    a_sel RA, b_sel IMMEDIATE, alu_op IMUL, update_flags ZF OF CF,
        rd_sel_source MODRM_REG, next_instruction;
imul6b_mem:
    segment DS, mem_read;
    a_sel MDR, b_sel IMMEDIATE, alu_op IMUL, update_flags ZF OF CF,
        rd_sel_source MODRM_REG, next_instruction;

.at 0x69;
    mar_write, mar_wr_sel EA, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem imul6b_reg;