// 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/>.

pushff_reg:
    a_sel RA, b_sel IMMEDIATE, immediate 0x2, alu_op SUB, rd_sel SP,
        rd_sel_source MICROCODE_RD_SEL, mar_write, mar_wr_sel Q,
        jmp pushff_reg_save, ra_modrm_rm_reg, segment DS;
pushff_mem:
    segment DS, mem_read, jmp pushff_mem_save, ra_sel SP;
pushff_reg_save:
    a_sel RA, alu_op SELA, mdr_write, segment_force, segment SS;
    segment_force, segment SS, mem_write, a_sel MAR, next_instruction;
pushff_mem_save:
    a_sel RA, b_sel IMMEDIATE, immediate 0x2, alu_op SUB, rd_sel SP,
        rd_sel_source MICROCODE_RD_SEL, mar_write, mar_wr_sel Q,
        segment_force, segment SS;
    segment_force, segment SS, mem_write, a_sel MAR, alu_op SELA,
        next_instruction;

#define PUSH_GPR(opcode, reg)                                           \
.at opcode;                                                             \
    ra_sel reg, jmp push_gpr;

#define PUSH_SR(opcode, reg)                                            \
.at opcode;                                                             \
    segment_force, segment reg, jmp push_sr;

PUSH_SR(0x06, ES)
PUSH_SR(0x0e, CS)
PUSH_SR(0x16, SS)
PUSH_SR(0x1e, DS)

PUSH_GPR(0x50, AX)
PUSH_GPR(0x51, CX)
PUSH_GPR(0x52, DX)
PUSH_GPR(0x53, BX)
PUSH_GPR(0x55, BP)
PUSH_GPR(0x56, SI)
PUSH_GPR(0x57, DI)

.auto_address;
push_gpr:
    a_sel RA, alu_op SELA, mdr_write, ra_sel SP;
    a_sel RA, b_sel IMMEDIATE, immediate 0x2, alu_op SUB, rd_sel SP,
        mar_write, mar_wr_sel Q, segment_force, segment SS;
    segment_force, segment SS, mem_write, a_sel MAR, rd_sel SP,
        rd_sel_source MICROCODE_RD_SEL, next_instruction;

// push SP, emulate broken 8086 behaviour: the decremented value gets pushed
// rather than the original value
.at 0x54;
    ra_sel SP, jmp push_sp;
.auto_address;
push_sp:
    a_sel RA, b_sel IMMEDIATE, immediate 0x2, alu_op SUB, rd_sel SP,
        mar_write, mar_wr_sel Q, mdr_write, segment_force, segment SS;
    segment_force, segment SS, mem_write, a_sel MAR, rd_sel SP,
        rd_sel_source MICROCODE_RD_SEL, next_instruction;

push_sr:
    b_sel SR, alu_op SELB, mdr_write, ra_sel SP;
    a_sel RA, b_sel IMMEDIATE, immediate 0x2, alu_op SUB, rd_sel SP,
        mar_write, mar_wr_sel Q, segment_force, segment SS;
    segment_force, segment SS, mem_write, a_sel MAR, rd_sel SP,
        rd_sel_source MICROCODE_RD_SEL, next_instruction;

.at 0x68;
    ra_sel SP, jmp push_immed16;
.auto_address;
push_immed16:
    a_sel RA, b_sel IMMEDIATE, immediate 0x2, alu_op SUB, mar_write,
        mar_wr_sel Q, rd_sel SP, rd_sel_source MICROCODE_RD_SEL;
    b_sel IMMEDIATE, alu_op SELB, mdr_write, segment_force, segment SS;
    segment_force, segment SS, mem_write, next_instruction;

.at 0x6a;
    ra_sel SP, jmp push_immed8;
.auto_address;
push_immed8:
    a_sel RA, b_sel IMMEDIATE, immediate 0x2, alu_op SUB, mar_write,
        mar_wr_sel Q, rd_sel SP, rd_sel_source MICROCODE_RD_SEL;
    b_sel IMMEDIATE, alu_op SELB, mdr_write, segment_force, segment SS;
    segment_force, segment SS, mem_write, next_instruction;

.at 0x9c;
    alu_op GETFLAGS, mdr_write, ra_sel SP, jmp pushf;
.auto_address;
pushf:
    a_sel RA, b_sel IMMEDIATE, immediate 0x2, alu_op SUB,
        mar_wr_sel Q, mar_write, segment_force, segment SS,
        rd_sel SP, rd_sel_source MICROCODE_RD_SEL;
    segment_force, segment SS, mem_write, next_instruction;

.at 0x60;
    ra_sel SP, jmp pusha;
.auto_address;
pusha:
    a_sel RA, ra_sel AX, b_sel IMMEDIATE, immediate 0x2, alu_op SUB,
        mar_write, mar_wr_sel Q;
    a_sel RA, alu_op SELA, mdr_write, segment_force, segment SS;
    segment_force, segment SS, mem_write,
        ra_sel CX, a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op SUB,
        mar_wr_sel Q, mar_write;

    a_sel RA, alu_op SELA, mdr_write, segment_force, segment SS;
    segment_force, segment SS, mem_write,
        ra_sel DX, a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op SUB,
        mar_wr_sel Q, mar_write;

    a_sel RA, alu_op SELA, mdr_write, segment_force, segment SS;
    segment_force, segment SS, mem_write,
        ra_sel BX, a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op SUB,
        mar_wr_sel Q, mar_write;

    a_sel RA, alu_op SELA, mdr_write, segment_force, segment SS;
    segment_force, segment SS, mem_write,
        ra_sel SP, a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op SUB,
        mar_wr_sel Q, mar_write;

    a_sel RA, alu_op SELA, mdr_write, segment_force, segment SS;
    segment_force, segment SS, mem_write,
        ra_sel BP, a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op SUB,
        mar_wr_sel Q, mar_write;

    a_sel RA, alu_op SELA, mdr_write, segment_force, segment SS;
    segment_force, segment SS, mem_write,
        ra_sel SI, a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op SUB,
        mar_wr_sel Q, mar_write;

    a_sel RA, alu_op SELA, mdr_write, segment_force, segment SS;
    segment_force, segment SS, mem_write,
        ra_sel DI, a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op SUB,
        mar_wr_sel Q, mar_write;
    a_sel RA, alu_op SELA, mdr_write, segment_force, segment SS;
    segment_force, segment SS, mem_write,
        rd_sel_source MICROCODE_RD_SEL, rd_sel SP, a_sel MAR, alu_op SELA,
        next_instruction;

.at 0x61;
    ra_sel SP, jmp popa;
.auto_address;
popa:
    a_sel RA, alu_op SELA, mar_wr_sel Q, mar_write, segment_force,
        segment SS;

    segment_force, segment SS, mem_read,
        rd_sel_source MICROCODE_RD_SEL, rd_sel DI, a_sel MDR;
    a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op ADD, mar_wr_sel Q,
        mar_write, segment_force, segment SS;

    segment_force, segment SS, mem_read,
        rd_sel_source MICROCODE_RD_SEL, rd_sel SI, a_sel MDR;
    a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op ADD, mar_wr_sel Q,
        mar_write, segment_force, segment SS;

    segment_force, segment SS, mem_read,
    // Skip over SP
        rd_sel_source MICROCODE_RD_SEL, rd_sel BP, a_sel MDR;
    a_sel MAR, b_sel IMMEDIATE, immediate 0x4, alu_op ADD, mar_wr_sel Q,
        mar_write, segment_force, segment SS;

    segment_force, segment SS, mem_read,
        rd_sel_source MICROCODE_RD_SEL, rd_sel BX, a_sel MDR;
    a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op ADD, mar_wr_sel Q,
        mar_write, segment_force, segment SS;

    segment_force, segment SS, mem_read,
        rd_sel_source MICROCODE_RD_SEL, rd_sel DX, a_sel MDR;
    a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op ADD, mar_wr_sel Q,
        mar_write, segment_force, segment SS;

    segment_force, segment SS, mem_read,
        rd_sel_source MICROCODE_RD_SEL, rd_sel CX, a_sel MDR;
    a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op ADD, mar_wr_sel Q,
        mar_write, segment_force, segment SS;

    segment_force, segment SS, mem_read,
        rd_sel_source MICROCODE_RD_SEL, rd_sel AX, a_sel MDR;
    a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op ADD,
        rd_sel_source MICROCODE_RD_SEL, rd_sel SP, next_instruction;