kernel-3.16.asm

;**********************Muse version 3.16******************

;*****************start of Muse 3 kernel code*************
[org 0x000]
[bits 16]

[SEGMENT .text]

;START #####################################################
    mov ax, 0x0100			;location where kernel is loaded
    mov ds, ax
    mov es, ax
    
    cli
    mov ss, ax				;stack segment
    mov sp, 0xFFFF			;stack pointer at 64k limit
    sti

    push dx
    push es
    xor ax, ax
    mov es, ax
    cli
    mov word [es:0x21*4], _int0x21	; setup interrupt service
    mov [es:0x21*4+2], cs
    sti
    pop es
    pop dx

    mov si, strWelcomeMsg   ; load message
    mov al, 0x01            ; request sub-service 0x01
    int 0x21

	call _shell				; call the shell
    
    int 0x19                ; reboot
;END #######################################################

_int0x21:
    _int0x21_ser0x01:       ;service 0x01
    cmp al, 0x01            ;see if service 0x01 wanted
    jne _int0x21_end        ;goto next check (now it is end)
    
	_int0x21_ser0x01_start:
    lodsb                   ; load next character
    or  al, al              ; test for NUL character
    jz  _int0x21_ser0x01_end
    mov ah, 0x0E            ; BIOS teletype
    mov bh, 0x00            ; display page 0
    mov bl, 0x07            ; text attribute
    int 0x10                ; invoke BIOS
    jmp _int0x21_ser0x01_start
    _int0x21_ser0x01_end:
    jmp _int0x21_end

    _int0x21_end:
    iret

_shell:
	_shell_begin:
	;move to next line
	call _display_endl

	;display prompt
	call _display_prompt

	;get user command
	call _get_command
	
	;split command into components
	call _split_cmd

	;check command & perform action

	; empty command
	_cmd_none:		
	mov si, strCmd0
	cmp BYTE [si], 0x00
	jne	_cmd_chkserial		;next command
	jmp _cmd_done


;****************start_custom_command*************************
	
; display serial port info

	_cmd_chkserial:		
	mov si, strCmd0
	mov di, cmdSerial
	mov cx,4
	repe	cmpsb
	jne	_cmd_info		;next command
	
	call _display_endl
	
initialize:
	mov     ah, 0           ;initialize opcode to zero
        mov     al, 0xA7   	;parameter data (initializing port - refer to PDF)
        mov     dx, 0           ;parameter data (initializing port - refer to PDF)
        int     0x14

transmit:
        mov     dx, 0           ;select COM1:
        mov     al, 'a'         ;character to transmit-could be anything
        mov     ah, 1           ;transmit opcode
        int     0x14

        cmp    ah, 0x80        	;Check for communication error
        jnz     serialerror
	jz serialpresent

serialerror:	
        mov     si, strNo   	;serial port not installed
	mov al, 0x01
	int 0x21
	
        
serialpresent:                  
        mov     si, strYes  	;serial port installed
	mov al, 0x01
	int 0x21
	
	jmp _cmd_done

;*************************************************************

; display OS info

	_cmd_info:
	mov si, strCmd0
	mov di, cmdInfo
	mov cx, 5
	repe	cmpsb
	jne _cmd_exit

	call _display_endl
	call _display_endl
	mov si, txtName		;display hacker info string
	mov al, 0x01
    	int 0x21
	 call _display_space
	mov si, strName		;display hacker name
	mov al, 0x01
    	int 0x21

	call _display_endl

	mov si, strOsName		;display OS name
	mov al, 0x01
    	int 0x21
	 call _display_space
	mov si, txtVersion		;display OS version
	mov al, 0x01
    	int 0x21
	 call _display_space

	mov si, strMajorVer		
	mov al, 0x01
    int 0x21

	mov si, strMinorVer
	mov al, 0x01
    int 0x21

	call _display_endl

	jmp _cmd_done

;*********************end_custom_command************************



	; exit shell
	_cmd_exit:		
	mov si, strCmd0
	mov di, cmdExit
	mov cx, 5
	repe	cmpsb
	jne	_cmd_unknown		;next command

	je _shell_end			;exit from shell

	_cmd_unknown:
	call _display_endl
	mov si, msgUnknownCmd		;unknown command
	mov al, 0x01
    int 0x21

	_cmd_done:

	;call _display_endl
	jmp _shell_begin
	
	_shell_end:
	int 0x19

_get_command:
	;initiate count
	mov BYTE [cmdChrCnt], 0x00
	mov di, strUserCmd

	_get_cmd_start:
	mov ah, 0x10		;get character
	int 0x16

	cmp al, 0x00		;check if extended key
	je _extended_key
	cmp al, 0xE0		;check if new extended key
	je _extended_key

	cmp al, 0x08		;check if backspace pressed
	je _backspace_key

	cmp al, 0x0D		;check if Enter pressed
	je _enter_key

	mov bh, [cmdMaxLen]		;check if maxlen reached
	mov bl, [cmdChrCnt]
	cmp bh, bl
	je	_get_cmd_start

	;add char to buffer, display it and start again
	mov [di], al			;add char to buffer
	inc di					;increment buffer pointer
	inc BYTE [cmdChrCnt]	;inc count

	mov ah, 0x0E			;display character
	mov bl, 0x07
	int 0x10
	jmp	_get_cmd_start

	_extended_key:			;extended key - do nothing now
	jmp _get_cmd_start

	_backspace_key:
	mov bh, 0x00			;check if count = 0
	mov bl, [cmdChrCnt]
	cmp bh, bl
	je	_get_cmd_start		;yes, do nothing
	
	dec BYTE [cmdChrCnt]	;dec count
	dec di

	;check if beginning of line
	mov	ah, 0x03		;read cursor position
	mov bh, 0x00
	int 0x10

	cmp dl, 0x00
	jne	_move_back
	dec dh
	mov dl, 79
	mov ah, 0x02
	int 0x10

	mov ah, 0x09		; display without moving cursor
	mov al, ' '
    mov bh, 0x00
    mov bl, 0x07
	mov cx, 1			; times to display
    int 0x10
	jmp _get_cmd_start

	_move_back:
	mov ah, 0x0E		; BIOS teletype acts on backspace!
    mov bh, 0x00
    mov bl, 0x07
    int 0x10
	mov ah, 0x09		; display without moving cursor
	mov al, ' '
    mov bh, 0x00
    mov bl, 0x07
	mov cx, 1			; times to display
    int 0x10
	jmp _get_cmd_start

	_enter_key:
	mov BYTE [di], 0x00
	ret

_split_cmd:
	;adjust si/di
	mov si, strUserCmd
	;mov di, strCmd0

	;move blanks
	_split_mb0_start:
	cmp BYTE [si], 0x20
	je _split_mb0_nb
	jmp _split_mb0_end

	_split_mb0_nb:
	inc si
	jmp _split_mb0_start

	_split_mb0_end:
	mov di, strCmd0

	_split_1_start:			;get first string
	cmp BYTE [si], 0x20
	je _split_1_end
	cmp BYTE [si], 0x00
	je _split_1_end
	mov al, [si]
	mov [di], al
	inc si
	inc di
	jmp _split_1_start

	_split_1_end:
	mov BYTE [di], 0x00

	;move blanks
	_split_mb1_start:
	cmp BYTE [si], 0x20
	je _split_mb1_nb
	jmp _split_mb1_end

	_split_mb1_nb:
	inc si
	jmp _split_mb1_start

	_split_mb1_end:
	mov di, strCmd1

	_split_2_start:			;get second string
	cmp BYTE [si], 0x20
	je _split_2_end
	cmp BYTE [si], 0x00
	je _split_2_end
	mov al, [si]
	mov [di], al
	inc si
	inc di
	jmp _split_2_start

	_split_2_end:
	mov BYTE [di], 0x00

	;move blanks
	_split_mb2_start:
	cmp BYTE [si], 0x20
	je _split_mb2_nb
	jmp _split_mb2_end

	_split_mb2_nb:
	inc si
	jmp _split_mb2_start

	_split_mb2_end:
	mov di, strCmd2

	_split_3_start:			;get third string
	cmp BYTE [si], 0x20
	je _split_3_end
	cmp BYTE [si], 0x00
	je _split_3_end
	mov al, [si]
	mov [di], al
	inc si
	inc di
	jmp _split_3_start

	_split_3_end:
	mov BYTE [di], 0x00

	;move blanks
	_split_mb3_start:
	cmp BYTE [si], 0x20
	je _split_mb3_nb
	jmp _split_mb3_end

	_split_mb3_nb:
	inc si
	jmp _split_mb3_start

	_split_mb3_end:
	mov di, strCmd3

	_split_4_start:			;get fourth string
	cmp BYTE [si], 0x20
	je _split_4_end
	cmp BYTE [si], 0x00
	je _split_4_end
	mov al, [si]
	mov [di], al
	inc si
	inc di
	jmp _split_4_start

	_split_4_end:
	mov BYTE [di], 0x00

	;move blanks
	_split_mb4_start:
	cmp BYTE [si], 0x20
	je _split_mb4_nb
	jmp _split_mb4_end

	_split_mb4_nb:
	inc si
	jmp _split_mb4_start

	_split_mb4_end:
	mov di, strCmd4

	_split_5_start:			;get last string
	cmp BYTE [si], 0x20
	je _split_5_end
	cmp BYTE [si], 0x00
	je _split_5_end
	mov al, [si]
	mov [di], al
	inc si
	inc di
	jmp _split_5_start

	_split_5_end:
	mov BYTE [di], 0x00

	ret

_display_space:
	mov ah, 0x0E                            ; BIOS teletype
	mov al, 0x20
    mov bh, 0x00                            ; display page 0
    mov bl, 0x07                            ; text attribute
    int 0x10                                ; invoke BIOS
	ret

_display_endl:
	mov ah, 0x0E		; BIOS teletype acts on newline!
    mov al, 0x0D
	mov bh, 0x00
    mov bl, 0x07
    int 0x10
	mov ah, 0x0E		; BIOS teletype acts on linefeed!
    mov al, 0x0A
	mov bh, 0x00
    mov bl, 0x07
    int 0x10
	ret

_display_prompt:
	mov si, strPrompt
	mov al, 0x01
	int 0x21
	ret

[SEGMENT .data]
    strWelcomeMsg   db  "Welcome to Muse 3, based on JOSH ver 3.0", 0x00
	strPrompt		db	"muse$>", 0x00
	cmdMaxLen		db	255			;maximum length of commands

	strName			db	"Gokul", 0x00
	strYes			db	13,10,"A serial port is present on your computer.", 0x00
	strNo			db	13,10,"A serial port was not found on your computer.", 0x00
	strOsName		db	"Muse", 0x00	;OS details
	strMajorVer		db	"3", 0x00
	strMinorVer		db	".16", 0x00

	

	cmdSerial		db	"chkserial", 0x00		; internal commands
	cmdVer			db	"ver", 0x00		; internal commands
	cmdExit			db	"exit", 0x00
	cmdInfo			db	"info", 0x00
	

	txtVersion		db	"Current OS version:", 0x00	;messages and other strings	
	txtName			db	"This version of JOSH was hacked by ", 0x00
	
	msgUnknownCmd	db	"Unknown command or bad filename.", 0x00
	

[SEGMENT .bss]
	strUserCmd	resb	256		;buffer for user commands
	cmdChrCnt	resb	1		;count of characters
	strCmd0		resb	256		;buffers for the command components
	strCmd1		resb	256
	strCmd2		resb	256
	strCmd3		resb	256
	strCmd4		resb	256

;********************end of Muse 3 kernel code********************