// 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/>.

#include <config.h>

.at 0x100;
opcode_fetch:
    ext_int_yield, jmp_opcode;

// See 0xcc in int.us for more details, this is the same thing but for a
// divide error.
.at 0x101;
divide_error:
    b_sel IMMEDIATE, immediate 0x0, alu_op SELB, tmp_wr_en, jmp do_int;

// See 0xcc in int.us for more details, this is the same thing but for a
// IRQ.
.at 0x12b;
    // IRQ number to temp
    a_sel MDR, b_sel IMMEDIATE, immediate 0x4, alu_op MUL, tmp_wr_en,
        jmp do_int;

// See 0xcc in int.us for more details, this is the same thing but for a
// NMI.
.at 0x12a;
nmi:
    b_sel IMMEDIATE, immediate 0x8, alu_op SELB, tmp_wr_en, jmp do_int;

// See 0xcc in int.us for more details, this is the same thing but for a
// single step trap.
.at 0x12c;
single_step:
    b_sel IMMEDIATE, immediate 0x4, alu_op SELB, tmp_wr_en, jmp do_int;

// Wait a single cycle for modrm decoding to complete
.at 0x12e;
modrm_decode:
    jmp_opcode;

.at 0x12f;
bad_opcode:
    jmp invalid_opcode;

#define INVALID_OPCODE(opc) \
.at opc; \
    jmp invalid_opcode

#define FILL(opc) \
.at opc; \
    next_instruction

INVALID_OPCODE(0x0f);
INVALID_OPCODE(0x63);
INVALID_OPCODE(0x64);
INVALID_OPCODE(0x65);
INVALID_OPCODE(0x66);
INVALID_OPCODE(0x67);
INVALID_OPCODE(0xf1);

FILL(0x26);
FILL(0x2e);
FILL(0x36);
FILL(0x3e);
FILL(0xf0);
FILL(0xf2);
FILL(0xf3);

.auto_address;
invalid_opcode:
    b_sel IMMEDIATE, immediate 0x18, alu_op SELB, tmp_wr_en, jmp do_int;

// Multiplexed add/adc/sub/sbb/cmp/xor/or/and
// r/m OP immed8
.at 0x80;
    mar_write, mar_wr_sel EA, jmp_dispatch_reg dispatch_80_81;
.auto_address;
dispatch_80_81:
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem ADD80_81_reg; // reg == 0
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem OR80_81_reg; // reg == 1
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem ADC80_81_reg; // reg == 2
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem SBB80_81_reg; // reg == 3
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem AND80_81_reg; // reg == 4
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem SUB80_81_reg; // reg == 5
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem XOR80_81_reg; // reg == 6
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem compSUB80_81_reg; // reg == 7

// Multiplexed add/adc/sub/sbb/cmp/xor/or/and
// r/m OP immed16
.at 0x81;
    mar_write, mar_wr_sel EA, jmp_dispatch_reg dispatch_80_81;

// Multiplexed add/adc/sub/sbb/cmp
// r/m OP immed8
.at 0x82;
    mar_write, mar_wr_sel EA, jmp_dispatch_reg dispatch_80_81;

// Multiplexed add/adc/sub/sbb/cmp/xor/or/and
// r/m OP immed16
.at 0x83;
    mar_write, mar_wr_sel EA, jmp_dispatch_reg dispatch_83;
.auto_address;
dispatch_83:
    segment DS, jmp_rm_reg_mem ADD83_reg; // reg == 0
    segment DS, jmp_rm_reg_mem OR83_reg; // reg == 1
    segment DS, jmp_rm_reg_mem ADC83_reg; // reg == 2
    segment DS, jmp_rm_reg_mem SBB83_reg; // reg == 3
    segment DS, jmp_rm_reg_mem AND83_reg; // reg == 4
    segment DS, jmp_rm_reg_mem SUB83_reg; // reg == 5
    segment DS, jmp_rm_reg_mem XOR83_reg; // reg == 6
    segment DS, jmp_rm_reg_mem compSUB83_reg; // reg == 7

// Multiplexed pop/8f
.at 0x8f;
    mar_write, mar_wr_sel EA, segment SS, jmp_dispatch_reg dispatch_8f;
.auto_address;
dispatch_8f:
    ra_sel SP, jmp_rm_reg_mem pop8f_reg; // reg == 0
    next_instruction; // reg == 1
    next_instruction; // reg == 2
    next_instruction; // reg == 3
    next_instruction; // reg == 4
    next_instruction; // reg == 5
    next_instruction; // reg == 6
    next_instruction; // reg == 7

// Multiplexed shift single 8-bit
.at 0xd0;
    width WAUTO, mar_write, mar_wr_sel EA, jmp_dispatch_reg dispatch_d0_d1;
.auto_address;
dispatch_d0_d1:
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem ROLd0_d1_reg;
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem RORd0_d1_reg;
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem RCLd0_d1_reg;
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem RCRd0_d1_reg;
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem SHLd0_d1_reg;
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem SHRd0_d1_reg;
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem SHLd0_d1_reg;
    width WAUTO, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem SARd0_d1_reg;

// Multiplexed shift single 8-bit by immediate
.at 0xc0;
    width W8, mar_write, mar_wr_sel EA,
	jmp_dispatch_reg dispatch_c0;
.auto_address;
dispatch_c0:
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE,
	ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem ROLc0_reg;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE,
	ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem RORc0_reg;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE,
	ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem RCLc0_reg;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE,
	ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem RCRc0_reg;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE,
	ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem SHLc0_reg;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE,
	ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem SHRc0_reg;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE,
	ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem SHLc0_reg;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE,
	ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem SARc0_reg;

// Multiplexed shift single 16-bit by immediate
.at 0xc1;
    mar_write, mar_wr_sel EA, jmp_dispatch_reg dispatch_c1;
.auto_address;
dispatch_c1:
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE, jmp ROLc1;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE, jmp RORc1;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE, jmp RCLc1;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE, jmp RCRc1;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE, jmp SHLc1;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE, jmp SHRc1;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE, jmp SHLc1;
    width W8, tmp_wr_en, alu_op SELB, b_sel IMMEDIATE, jmp SARc1;

// Multiplexed shift single 16-bit
.at 0xd1;
    mar_write, mar_wr_sel EA, jmp_dispatch_reg dispatch_d0_d1;

// Multiplexed shift multiple 8-bit
.at 0xd2;
    width WAUTO, mar_write, mar_wr_sel EA, jmp_dispatch_reg dispatch_d2_d3;
.auto_address;
dispatch_d2_d3:
    width WAUTO, ra_modrm_rm_reg, rb_cl, segment DS, jmp ROLd2_d3;
    width WAUTO, ra_modrm_rm_reg, rb_cl, segment DS, jmp RORd2_d3;
    width WAUTO, ra_modrm_rm_reg, rb_cl, segment DS, jmp RCLd2_d3;
    width WAUTO, ra_modrm_rm_reg, rb_cl, segment DS, jmp RCRd2_d3;
    width WAUTO, ra_modrm_rm_reg, rb_cl, segment DS, jmp SHLd2_d3;
    width WAUTO, ra_modrm_rm_reg, rb_cl, segment DS, jmp SHRd2_d3;
    width WAUTO, ra_modrm_rm_reg, rb_cl, segment DS, jmp SHLd2_d3;
    width WAUTO, ra_modrm_rm_reg, rb_cl, segment DS, jmp SARd2_d3;

// Multiplexed shift multiple 16-bit
.at 0xd3;
    mar_write, mar_wr_sel EA, jmp_dispatch_reg dispatch_d2_d3;

// Multiplexed neg/mul/not/test/div 8 bit
.at 0xf6;
    width W8, mar_write, mar_wr_sel EA, jmp_dispatch_reg dispatch_f6;
.auto_address;
dispatch_f6:
    width W8, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem compANDf6_reg; // reg == 0
    width W8, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem compANDf6_reg; // reg == 1
    width W8, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem notf6_reg; // reg == 3
    width W8, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem negf6_reg; // reg == 3
    width W8, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem mulf6_reg; // reg == 4
    width W8, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem imulf6_reg; // reg == 5
    width W8, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem divf6_reg; // reg == 6
    width W8, ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem idivf6_reg; // reg == 7

// Multiplexed neg/mul/not/test/div 16 bit
.at 0xf7;
    mar_write, mar_wr_sel EA, jmp_dispatch_reg dispatch_f7;
.auto_address;
dispatch_f7:
    ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem compANDf7_reg; // reg == 0
    ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem compANDf7_reg; // reg == 1
    ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem notf6_reg; // reg == 2
    ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem negf6_reg; // reg == 3
    ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem mulf7_reg; // reg == 4
    ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem imulf7_reg; // reg == 5
    ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem divf7_reg; // reg == 6
    ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem idivf7_reg; // reg == 7

// Multiplexed push/inc/jmp/call/ff
.at 0xff;
    mar_write, mar_wr_sel EA, segment DS, jmp_dispatch_reg dispatch_ff;
.auto_address;
dispatch_ff:
    ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem inc_fe_reg; // reg == 0
    ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem dec_fe_reg; // reg == 1
    ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem callff_indirect_intra_reg; // reg == 2
    segment_force, segment CS, jmp_rm_reg_mem callff_indirect_inter_reg; // reg == 3
    ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem jmpff_indirect_intra_reg; // reg == 4
    ra_modrm_rm_reg, segment DS, jmp_rm_reg_mem jmpff_indirect_inter_reg; // reg == 5
    ra_sel SP, segment DS, jmp_rm_reg_mem pushff_reg; // reg == 6
    jmp invalid_opcode;

.at 0x129;
    jmp reset;

.auto_address;
reset:
    b_sel IMMEDIATE, alu_op SELB, immediate 0x0, rd_sel_source MICROCODE_RD_SEL,
        rd_sel AX;
    b_sel IMMEDIATE, alu_op SELB, immediate 0x0, rd_sel_source MICROCODE_RD_SEL,
        rd_sel CX;
    b_sel IMMEDIATE, alu_op SELB, immediate 0x0, rd_sel_source MICROCODE_RD_SEL,
        rd_sel DX;
    b_sel IMMEDIATE, alu_op SELB, immediate 0x0, rd_sel_source MICROCODE_RD_SEL,
        rd_sel BX;
    b_sel IMMEDIATE, alu_op SELB, immediate 0x0, rd_sel_source MICROCODE_RD_SEL,
        rd_sel SP;
    b_sel IMMEDIATE, alu_op SELB, immediate 0x0, rd_sel_source MICROCODE_RD_SEL,
        rd_sel BP;
    b_sel IMMEDIATE, alu_op SELB, immediate 0x0, rd_sel_source MICROCODE_RD_SEL,
        rd_sel SI;
    b_sel IMMEDIATE, alu_op SELB, immediate 0x0, rd_sel_source MICROCODE_RD_SEL,
        rd_sel DI;
    b_sel IMMEDIATE, alu_op SELB, immediate 0x0, segment_force, segment ES,
        segment_wr_en;
    b_sel IMMEDIATE, alu_op SELB, immediate 0xffff, segment_force, segment CS,
        segment_wr_en;
    b_sel IMMEDIATE, alu_op SELB, immediate 0x0, segment_force, segment SS,
        segment_wr_en;
    b_sel IMMEDIATE, alu_op SELB, immediate 0x0, segment_force, segment DS,
        segment_wr_en;
    next_instruction, jmp opcode_fetch;

.auto_address;
write_16_complete:
    segment DS, mem_write, next_instruction;

write_complete:
    segment DS, mem_write, width WAUTO, next_instruction;