加载用户程序的监控程序

%macro print 4	; string, length, x, y
	mov ax, cs
	mov ds, ax
	mov bp, %1
	mov ax, ds
	mov es, ax
	mov cx, %2
	mov ah, 13h
	mov al, 00h
	mov bh, 00h
	mov bl, %3	; 根据行号自动变色
	mov dh, %3
	mov dl, %4
	int 10h
%endmacro

	N equ 12	;显示区域高度
	M equ 32	;显示区域宽度减去字符串长度
	TOP equ 2	;显示区域上端点
	LEFT equ 40	;显示区域左端点
	LENGTH equ 8	;字符串的长度
	DELAY equ 99999999
	org 0A100h
	mov ax,0B800h
	mov gs,ax	; GS = 0xB800h，文本窗口显存起始地址

myLoop:
	dec dword[count]	; 递减计数变量
	jnz myLoop	; >0：跳转
	mov dword[count], DELAY

	mov word ax, [t]	; ax = t
	mov word bx,2*N-2
	xor dx, dx	; clear dx and prepare for division
	div bx  ; dx = t mod (2N - 2)
	cmp dx, N ; compare dx and n
	jb xok  ; if (dx < n) jump xok
	sub bx, dx
	mov dx, bx ; dx = 2n - 2 - dx
xok:
	mov word[x], dx
	add word[x], TOP

	mov word ax, [t]
	mov word bx, 2*M-2
	xor dx, dx
	div bx
	cmp dx, M
	jb yok
	sub bx, dx
	mov dx, bx
yok:
	mov word [y],dx
	add word [y],LEFT

	inc word[t]
	print message, LENGTH, [x], [y]
	int 20h
	jmp myLoop
datadef:
	count dd 1
	t dw 0
	x dw 1
	y dw 0
	message db ' wu-kan '

OffSetOfUserPrg equ 0A100h
org  7c00h
%macro print 4	; string, length, x, y
	mov ax, cs
	mov ds, ax
	mov bp, %1
	mov ax, ds
	mov es, ax
	mov cx, %2
	mov ah, 13h
	mov al, 00h
	mov bh, 00h
	mov bl, 07h	; 黑底白字
	mov dh, %3
	mov dl, %4
	int 10h
%endmacro

mov ax, 0000h
mov es, ax
mov ax, 20h
mov bx, 4
mul bx
mov si, ax
mov ax, _int20h
mov [es:si], ax
add si, 2
mov ax, cs
mov [es:si], ax
begin:
	call cls
	print msg, msglen, 0, 0
input:
	mov ah, 0
	int 16h
	cmp al, '1'
	jl input
	cmp al, '4'
	jg input
	mov [sectorNum], al
	call cls
	print msg1, msglen1, 0, 0
	print sectorNum, 1, 0, 16

	mov cl, [sectorNum]
	sub cl, '0'-1  ;从第二个扇区开始
	mov ax, cs
	mov es, ax
	mov ah, 2
	mov al, 1
	mov dl, 0
	mov dh, 0
	mov ch, 0
	mov bx, OffSetOfUserPrg
	int 13H
	jmp OffSetOfUserPrg
cls:
	mov ax, 0B800h
	mov es, ax
	mov si, 0
	mov cx, 80*25
	mov dx, 0
	clsLoop:
		mov [es:si], dx
		add si, 2
	loop clsLoop
	ret
int20h:
	mov ah, 01h
	int 16h
	jz noclick
	mov ah, 00h
	int 16h
	cmp ax, 2e03h	; 检测Ctrl + C
	jne noclick
	jmp begin
noclick:
	iret
datadef:
	msg db 'Welcome to WuKOS, press 1~4 to run a program.'
	msglen equ ($-msg)
	msg1 db 'This is program 0, press Ctrl + C to return.'
	msglen1 equ ($-msg1)
	sectorNum db '1'