Эмулятор процессора Intel 8086 версия 4.05 (ENG) / asm_files / micro-os_kernel.asm

Assembler Source Code a:link {text-decoration: none} a:visited {text-decoration: none} a:hover {text-decoration: none; color:#ff0000}     ; micro-os_kernel.asm name "kernel" ; this is a very basic example ; of a tiny operating system. ; ; this is kernel module! ; ; it is assumed that this machine ; code is loaded by 'micro-os_loader.asm' ; from floppy drive from: ; cylinder: 0 ; sector: 2 ; head: 0 ;================================================= ; how to test micro-operating system: ; 1. compile micro-os_loader.asm ; 2. compile micro-os_kernel.asm ; 3. compile writebin.asm ; 4. insert empty floppy disk to drive a: ; 5. from command prompt type: ; writebin loader.bin ; writebin kernel.bin /k ;================================================= ; directive to create bin file: #make_bin# ; where to load? (for emulator. all these values are saved into .binf file) #load_segment=0800# #load_offset=0000# ; these values are set to registers on load, actually only ds, es, cs, ip, ss, sp are ; important. these values are used for the emulator to emulate real microprocessor state ; after micro-os_loader transfers control to this kernel (as expected). #al=0b# #ah=00# #bh=00# #bl=00# #ch=00# #cl=02# #dh=00# #dl=00# #ds=0800# #es=0800# #si=7c02# #di=0000# #bp=0000# #cs=0800# #ip=0000# #ss=07c0# #sp=03fe# ; this macro prints a char in al and advances ; the current cursor position: putc macro char push ax mov al, char mov ah, 0eh int 10h pop ax endm ; sets current cursor position: gotoxy macro col, row push ax push bx push dx mov ah, 02h mov dh, row mov dl, col mov bh, 0 int 10h pop dx pop bx pop ax endm print macro x, y, attrib, sdat LOCAL s_dcl, skip_dcl, s_dcl_end pusha mov dx, cs mov es, dx mov ah, 13h mov al, 1 mov bh, 0 mov bl, attrib mov cx, offset s_dcl_end - offset s_dcl mov dl, x mov dh, y mov bp, offset s_dcl int 10h popa jmp skip_dcl s_dcl DB sdat s_dcl_end DB 0 skip_dcl: endm ; kernel is loaded at 0800:0000 by micro-os_loader org 0000h ; skip the data and function delaration section: jmp start ; first byte of this jump instruction is 0E9h it is ; used by loader to determine if we had a sucessful launch. ;==== data section ===================== ; welcome message: msg db 'welcome to micro-os!', 0 cmd_size equ 10 ; size of command_buffer command_buffer db cmd_size dup('b') clean_str db cmd_size dup(' '), 0 prompt db '>', 0 ; commands: chelp db 'help', 0 chelp_tail: ccls db 'cls', 0 ccls_tail: cquit db 'quit', 0 cquit_tail: cexit db 'exit', 0 cexit_tail: creboot db 'reboot', 0 creboot_tail: help_msg db 'thank you for using micro-os!', 0Dh,0Ah db 'list of supported commands:', 0Dh,0Ah db 'help - print out this list.', 0Dh,0Ah db 'cls - clear the screen.', 0Dh,0Ah db 'reboot - reboot the machine.', 0Dh,0Ah db 'quit - same as reboot.', 0Dh,0Ah db 'exit - same as quit.', 0Dh,0Ah db 'more to come!', 0Dh,0Ah, 0 unknown db 'unknown command: ' , 0 ;====================================== start: ; set data segment: push cs pop ds ; set default video mode 80x25: mov ah, 00h mov al, 03h int 10h ; blinking disabled for compatibility with dos/bios, ; emulator and windows prompt never blink. mov ax, 1003h mov bx, 0 ; disable blinking. int 10h ; clear screen: call clear_screen ; print out the message: lea si, msg call print_string eternal_loop: call get_command call process_cmd ; make eternal loop: jmp eternal_loop ;=========================================== get_command proc near ; set cursor position to bottom ; of the screen: mov ax, 40h mov es, ax mov al, es:[84h] gotoxy 0, al ; clear command line: lea si, clean_str call print_string gotoxy 0, al ; show prompt: lea si, prompt call print_string ; wait for a command: mov dx, cmd_size ; buffer size. lea di, command_buffer call get_string ret get_command endp ;=========================================== process_cmd proc near ;//// check commands here /// ; set es to ds push ds pop es cld ; forward compare. ; compare command buffer with 'help' lea si, command_buffer mov cx, chelp_tail - offset chelp ; size of ['help',0] string. lea di, chelp repe cmpsb je help_command ; compare command buffer with 'cls' lea si, command_buffer mov cx, ccls_tail - offset ccls ; size of ['cls',0] string. lea di, ccls repe cmpsb jne not_cls jmp cls_command not_cls: ; compare command buffer with 'quit' lea si, command_buffer mov cx, cquit_tail - offset cquit ; size of ['quit',0] string. lea di, cquit repe cmpsb je reboot_command ; compare command buffer with 'exit' lea si, command_buffer mov cx, cexit_tail - offset cexit ; size of ['exit',0] string. lea di, cexit repe cmpsb je reboot_command ; compare command buffer with 'reboot' lea si, command_buffer mov cx, creboot_tail - offset creboot ; size of ['reboot',0] string. lea di, creboot repe cmpsb je reboot_command ;//////////////////////////// ; if gets here, then command is ; unknown... mov al, 1 call scroll_t_area ; set cursor position just ; above prompt line: mov ax, 40h mov es, ax mov al, es:[84h] dec al gotoxy 0, al lea si, unknown call print_string lea si, command_buffer call print_string mov al, 1 call scroll_t_area jmp processed ; +++++ 'help' command ++++++ help_command: ; scroll text area 9 lines up: mov al, 9 call scroll_t_area ; set cursor position 9 lines ; above prompt line: mov ax, 40h mov es, ax mov al, es:[84h] sub al, 9 gotoxy 0, al lea si, help_msg call print_string mov al, 1 call scroll_t_area jmp processed ; +++++ 'cls' command ++++++ cls_command: call clear_screen jmp processed ; +++ 'quit', 'exit', 'reboot' +++ reboot_command: call clear_screen print 5,2,0011_1111b," please eject any floppy disks " print 5,3,0011_1111b," and press any key to reboot... " mov ax, 0 ; wait for any key.... int 16h ; store magic value at 0040h:0072h: ; 0000h - cold boot. ; 1234h - warm boot. mov ax, 0040h mov ds, ax mov w.[0072h], 0000h ; cold boot. jmp 0ffffh:0000h ; reboot! ; ++++++++++++++++++++++++++ processed: ret process_cmd endp ;=========================================== ; scroll all screen except last row ; up by value specified in al scroll_t_area proc near mov dx, 40h mov es, dx ; for getting screen parameters. mov ah, 06h ; scroll up function id. mov bh, 07 ; attribute for new lines. mov ch, 0 ; upper row. mov cl, 0 ; upper col. mov di, 84h ; rows on screen -1, mov dh, es:[di] ; lower row (byte). dec dh ; don't scroll bottom line. mov di, 4ah ; columns on screen, mov dl, es:[di] dec dl ; lower col. int 10h ret scroll_t_area endp ;=========================================== ; get characters from keyboard and write a null terminated string ; to buffer at DS:DI, maximum buffer size is in DX. ; 'enter' stops the input. get_string proc near push ax push cx push di push dx mov cx, 0 ; char counter. cmp dx, 1 ; buffer too small? jbe empty_buffer ; dec dx ; reserve space for last zero. ;============================ ; eternal loop to get ; and processes key presses: wait_for_key: mov ah, 0 ; get pressed key. int 16h cmp al, 0Dh ; 'return' pressed? jz exit cmp al, 8 ; 'backspace' pressed? jne add_to_buffer jcxz wait_for_key ; nothing to remove! dec cx dec di putc 8 ; backspace. putc ' ' ; clear position. putc 8 ; backspace again. jmp wait_for_key add_to_buffer: cmp cx, dx ; buffer is full? jae wait_for_key ; if so wait for 'backspace' or 'return'... mov [di], al inc di inc cx ; print the key: mov ah, 0eh int 10h jmp wait_for_key ;============================ exit: ; terminate by null: mov [di], 0 empty_buffer: pop dx pop di pop cx pop ax ret get_string endp ; print a null terminated string at current cursor position, ; string address: ds:si print_string proc near push ax ; store registers... push si ; next_char: mov al, [si] cmp al, 0 jz printed inc si mov ah, 0eh ; teletype function. int 10h jmp next_char printed: pop si ; re-store registers... pop ax ; ret print_string endp ; clear the screen by scrolling entire screen window, ; and set cursor position on top. ; default attribute is set to white on blue. clear_screen proc near push ax ; store registers... push ds ; push bx ; push cx ; push di ; mov ax, 40h mov ds, ax ; for getting screen parameters. mov ah, 06h ; scroll up function id. mov al, 0 ; scroll all lines! mov bh, 1001_1111b ; attribute for new lines. mov ch, 0 ; upper row. mov cl, 0 ; upper col. mov di, 84h ; rows on screen -1, mov dh, [di] ; lower row (byte). mov di, 4ah ; columns on screen, mov dl, [di] dec dl ; lower col. int 10h ; set cursor position to top ; of the screen: mov bh, 0 ; current page. mov dl, 0 ; col. mov dh, 0 ; row. mov ah, 02 int 10h pop di ; re-store registers... pop cx ; pop bx ; pop ds ; pop ax ; ret clear_screen endp

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