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 .

.at 0xe9;

    read_immed, jmp jmpe9;

.auto_address;

jmpe9:

    a_sel IP, b_sel IMMEDIATE, alu_op ADD, load_ip,

        next_instruction;

.at 0xea;

    read_immed, jmp jmpea;

.auto_address;

jmpea:

    b_sel IMMEDIATE, alu_op SELB, load_ip;

    // read_immed can't be combined in the previous microinstruction as

    // otherwise it will clobber the immediate during stalling whilst load_ip

    // is asserted and we'll load an invalid IP.

    read_immed;

    b_sel IMMEDIATE, alu_op SELB, segment_wr_en,

        segment_force, segment CS, next_instruction;

.at 0xeb;

    width W8, read_immed, jmp jmpeb;

.auto_address;

jmpeb:

    a_sel IP, b_sel IMMEDIATE, alu_op ADD, load_ip,

        next_instruction;

jmpff_indirect_intra_reg:

    a_sel RA, alu_op SELA, load_ip,

        next_instruction;

jmpff_indirect_intra_mem:

    segment DS, mem_read;

    a_sel MDR, alu_op SELA, load_ip,

        next_instruction;

jmpff_indirect_inter_reg:

    next_instruction;

jmpff_indirect_inter_mem:

    segment DS, mem_read;

    a_sel MDR, alu_op SELA, load_ip;

    immediate 0x2, a_sel MAR, b_sel IMMEDIATE, alu_op ADD,

        mar_wr_sel Q, mar_write, segment DS;

    segment DS, mem_read;

    a_sel MDR, alu_op SELA, segment_wr_en,

        segment_force, segment CS, next_instruction;

// JCXZ

.at 0xe3;

    width W8, read_immed, jmp jcxz;

.auto_address;

jcxz:

    rb_cl;

    jmp_rb_zero jcxz_taken;

    next_instruction;

jcxz_taken:

    a_sel IP, b_sel IMMEDIATE, alu_op ADD, load_ip, next_instruction;

#define JUMP(opcode) \

.at opcode; \

    width W8, read_immed, jmp test_jump

JUMP(0x70);

JUMP(0x71);

JUMP(0x72);

JUMP(0x73);

JUMP(0x74);

JUMP(0x75);

JUMP(0x76);

JUMP(0x77);

JUMP(0x78);

JUMP(0x79);

JUMP(0x7a);

JUMP(0x7b);

JUMP(0x7c);

JUMP(0x7d);

JUMP(0x7e);

JUMP(0x7f);

.auto_address;

test_jump:

    jmp_if_taken jmp_taken;

    next_instruction;

jmp_taken:

    a_sel IP, b_sel IMMEDIATE, alu_op ADD, load_ip, next_instruction;