Assembly 更改IRQ8 ISR
我想每隔55ns打印一次“你好”。我做错了什么Assembly 更改IRQ8 ISR,assembly,x86-16,Assembly,X86 16,我想每隔55ns打印一次“你好”。我做错了什么 .model small .stack 100h pusha MACRO push ax push bx push cx push dx push sp push bp push si push di ENDM popa MACRO pop di pop si pop bp pop sp pop dx pop cx pop b
.model small
.stack 100h
pusha MACRO
push ax
push bx
push cx
push dx
push sp
push bp
push si
push di
ENDM
popa MACRO
pop di
pop si
pop bp
pop sp
pop dx
pop cx
pop bx
pop ax
ENDM
.data
old_vec dw 1 dup(?)
old_seg dw 1 dup(?)
HELLO db "HELLO.$"
.code
start:
mov ax, @data
mov ds, ax
mov ax, es:[20h]
mov bx, es:[20h+2] ;saving the old ISR ADDRESS
mov old_vec, ax
mov old_seg, bx
mov es:[20h], OFFSET PRINT_HELLO ; setting the ivt to point to PRINT_HELLO
mov es:[20h + 2], SEG PRINT_HELLO
COMMENT @
mov bx, offset old_vec
mov ax, word ptr[bx]
mov es:[20h], ax
mov bx, offset old_seg
mov ax, word ptr[bx]
mov es:[20h+2], ax
@
;for1:
; jmp for1
.exit
mov ah, 4ch
int 21h
PRINT_HELLO proc far
pushf
pusha
mov ax, offset old_seg
mov bx, ax
mov es, word ptr[bx]
mov bx, offset old_vec
mov bx, word ptr[bx]
call far PTR es:[bx] ; calling the old interrupt handler
mov dx, offset HELLO
mov ah, 09h
int 21h
popa
iret
PRINT_HELLO endp
end
CSDSESSSORG 256; This program prints a message every 55 milliseconds
; until a key is pressed
ORG 256
xor ax, ax
mov es, ax
More: mov al, [es:046Ch] ; BIOS.Timer
Wait: cmp al, [es:046Ch]
je Wait
mov dx, Msg
mov ah, 09h ; DOS.PrintString
int 21h
mov ah, 01h ; BIOS.TestKey
int 16h ; -> AX ZF
jz More
mov ah, 00h ; BIOS.GetKey
int 16h ; -> AX
mov ax, 4C00h ; DOS.Terminate
int 21h
; --------------------------------
Msg db 'Hello, once every 55 milliseconds!', 13, 10, '$'
; This program prints a message every 55 milliseconds
; until a key is pressed
ORG 256
mov ax, 351Ch ; DOS.GetInterruptVector
int 21h ; -> ES:BX
mov [chain+1], bx
mov [chain+3], es
mov dx, int1C
mov ax, 251Ch ; DOS.SetInterruptVector
int 21h
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
; In the 'main' part you can freely change DS, ES, and SS segment registers
main: mov ah, 01h ; BIOS.TestKey
int 16h ; -> AX ZF
jz main
mov ah, 00h ; BIOS.GetKey
int 16h ; -> AX
; In the 'main' part you can freely change DS, ES, and SS segment registers
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
mov dx, [cs:chain+1]
mov ds, [cs:chain+3]
mov ax, 251Ch ; DOS.SetInterruptVector
int 21h
mov ax, 4C00h ; DOS.Terminate
int 21h
; --------------------------------
int1C: push ax bx si
cld
mov bx, 0007h ; DisplayPage and GraphicsColor
mov si, Msg
.more: lods byte [cs:si]
mov ah, 0Eh ; BIOS.Teletype
int 10h
cmp al, 10
jne .more
pop si bx ax
chain: jmp far 0:0 ; Chaining to the old interrupt handler
Msg: db 'Hello, once every 55 milliseconds!', 13, 10, '$'
; --------------------------------
- 使用BIOS输出功能可避免DOS重入问题
- 将旧向量存储在远跳转指令上可以避免操作段寄存器
- 将消息放在代码段中便于访问
- DOS函数25h和35h在更改中断向量时易于使用
虽然可以通过TSR完成上述所有操作，但将如此多的文本字符快速连续地放在屏幕上将不可避免地造成真正的混乱！请记住，在使用屏幕时，前台程序（DOS命令行或用户应用程序）是首选程序。不要按下并弹出
sppush spdsesdsespushf调用far[cs:old\u vec]pushfiretcsip