ORG 0x0000
EN EQU %10000000
RW EQU %01000000
RS EQU %00100000

PORTA EQU (0x00)
PORTB EQU (0x01)
DDRA EQU (0x02)
DDRB EQU (0x03)

START:
    LD SP, 0xFFFE ; stack pointer at end of ram cca

    LD B, %10000000
    LD C, 0x2
    LD A, 0x0
    LD (BC), A ; so the ram address of 0x8002 is 0x0

    LD A, 0xCF
    OUT (C), A ; control mode on 0x2
    LD A, 0x0
    OUT (C), A ; all are outputs on 0x2
    LD A, %00000111
    OUT (C), A ; interrupt config, not sure if necessary


    LD A, 0x0
    LD C, 0x3
    LD (BC), A ; so the ram addres of 0x8003 is 0x0

    LD C, 0x1
    LD (BC), A ; so the 0x8001 is also 0x0
    LD C, 0x0
    LD (BC), A ; so the 0x8000 is also 0x0

    LD C, 0x3
    LD A, 0xCF
    OUT (C), A ; control mode
    LD A, %00010000
    OUT (C), A ; all are outputs except 4
    LD A, 0x0
    OUT (C), A ; vector is 0 i suppose

    ; this is the latest addition
    LD A, %10010111
    OUT (C), A ; interrupt config
    LD A, %11101111 ; monitor only byte 4
    OUT (C), A

    LD A, 0x02
    LD I, A ; interrupt register, upper byte
    EI
    IM 2

    LD A, %00110000
    CALL LCD_INSTRUCTION
    LD A, %00110000
    CALL LCD_INSTRUCTION
    LD A, %00110000
    CALL LCD_INSTRUCTION


    LD A, %00111000 ; set 8-bit mode, 2 line display, 5x8 font
    CALL LCD_INSTRUCTION
    LD A, %00001110 ; display on, cursor on, blink off
    CALL LCD_INSTRUCTION
    LD A, %00000110 ; increment and shift
    CALL LCD_INSTRUCTION
    JP MAIN

    ORG 66h ; non maskable interrupt
    CALL NMI
    RETI

    ORG 0x100
MAIN:
    LD A, %00000001 ; clear display
    CALL LCD_INSTRUCTION
    LD HL,msg
LOOP:
    LD A, (HL)
    OR A
    JP Z, END
    CALL PRINT_CHAR
    INC HL
    JP LOOP
END:
    JP END

    ORG 0x200
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234
    DW 0x1234

    ORG 0x1234
INTERRUPTION:
    DI
    EX  AF, AF'
    EXX
    LD A, %00000001 ; clear display
    CALL LCD_INSTRUCTION
    LD HL,msg_lol2
LOOP_INT3:
    LD A, (HL)
    OR A
    JP Z, END_LOOP3
    CALL PRINT_CHAR
    INC HL
    JP LOOP_INT3
END_LOOP3:
    EXX
    EX AF, AF'
    EI
    HALT
    RETI



LCD_WAIT:
    PUSH AF
    LD C, 0x2
    LD A, 0xCF
    OUT (C), A
    LD A, 0xFF
    OUT (C), A ; port A is input
LCD_BUSY:
    LD A, RW
    LD C, 0x1
    OUT (C), A

    OR EN
    OUT (C), A

    LD C, 0x0
    IN A, (C)
    AND %10000000
    JR NZ, LCD_BUSY

    LD A, RW
    LD C, 0x1
    OUT (C), A

    LD C, 0x2
    LD A, 0xCF
    OUT (C), A
    LD A, 0x00
    OUT (C), A ; port A is input
    POP AF
    RET

LCD_INSTRUCTION:
    CALL LCD_WAIT
    LD C, 0x0
    OUT (C), A ; put the contents of A register on PORT A

    LD C, 0x1
    LD A, 0x0
    OUT (C), A

    LD A, EN
    OUT (C), A

    LD A, 0x0
    OUT (C), A

    RET

DELAY:
    LD HL, 5000
DELAY1:
    DEC HL
    LD A, H
    OR L
    JR NZ, DELAY1
    RET ; if zero, return

PRINT_CHAR:
    CALL LCD_WAIT

    LD C, 0x0
    OUT (C), A


    LD C, 0x1
    LD A, RS
    OUT (C), A

    LD A, RS
    OR EN
    OUT (C), A

    LD A, RS
    OUT (C), A
    RET

NMI:
    DI
    EX  AF, AF'
    EXX
    LD HL,msg_nmi
LOOP_INT2:
    LD A, (HL)
    OR A
    JP Z, END_LOOP2
    CALL PRINT_CHAR
    INC HL
    JP LOOP_INT2
END_LOOP2:
    EXX
    EX AF, AF'
    EI
    RET



msg: .asciz "Hello World"
msg_nmi: .asciz "NMI"
msg_int: .asciz "INT"
msg_lol2: .asciz "1234"
msg_lol: .asciz "3412"


    ORG 0x3412
INTERRUPTION22:
    DI
    EX  AF, AF'
    EXX
    LD A, %00000001 ; clear display
    CALL LCD_INSTRUCTION
    LD HL,msg_lol
LOOP_INT22:
    LD A, (HL)
    OR A
    JP Z, END_LOOP22
    CALL PRINT_CHAR
    INC HL
    JP LOOP_INT22
END_LOOP22:
    EXX
    EX AF, AF'
    EI
    HALT
    RETI