23:01
Description: An example of multi-tasking in Assembly Language
[org 0x0100]
jmp
start
PCB: times 9*16 dw 0
stack: times 9*256 dw 0
nextPCB: dw 1
current: dw 0
string: db ' Visit www.hazacs.com for more...',0
xPos: dw 0
yPos:dw 0
clearScreen:
pusha
mov ax , 0xB800
mov es , ax
mov di , 0
mov ax , 0x0720
mov cx , 2000
rep stosw
popa
ret
delay:
pusha
mov dx , 0
outerDelay:
mov cx , 0XFFFF
putDelay:
loop
putDelay
inc dx
cmp dx , 0x0001
jl
outerDelay
popa
ret
strlen:
push bp
mov bp , sp
push ax
push cx
push es
push di
les di , [bp+4]
mov cx , 0xFFFF
xor al , al
repne scasb
mov ax , 0xFFFF
sub ax , cx
dec ax
mov [bp+8] , ax
pop di
pop es
pop cx
pop ax
pop bp
ret 4
colorTask: ;[BP+8]=x-coord [BP+6]=y-coord [BP+4]=color
push bp
mov bp , sp
push ax
push bx
push cx
push dx
push si
push di
push es
push 0xB800
pop es
mov al , 80
mul byte [bp+6]
add ax , [bp+8]
shl ax , 1
mov bx , ax
printColor:
mov ax , [bp+4]
mov dx , 0
printOuterLoop:
mov di , bx
mov cx , 6
printInnerLoop:
stosw
add di , 158
loop printInnerLoop
call delay
inc dx
cmp dx , 40
jnl rubColor
add bx , 2
jmp printOuterLoop
rubColor:
mov ax , 0x0720
mov dx , 0
rubOuterLoop:
mov di , bx
mov cx , 6
rubInnerLoop:
stosw
add di , 158
loop rubInnerLoop
call delay
inc dx
cmp dx , 40
jnl printColor
sub bx , 2
jmp rubOuterLoop
pop es
pop di
pop si
pop dx
pop cx
pop bx
pop ax
pop bp
ret 6
stringTask: ;[BP+6]=x-coord [BP+4]=y-coord
push bp
mov bp , sp
push ax
push bx
push cx
push dx
push si
push di
push es
push cs
pop ds
push 0xB800
pop es
mov al , 80
mov cl , [bp+6]
add cl , 2
mul cl
add ax , [bp+8]
shl ax , 1
mov bx , ax
mov di , [bp+4]
sub sp , 2
push ds
push di
call
strlen
pop dx ;DX=size of the string
printString:
mov di , bx
mov si , [bp+4]
mov ah , 0x07
mov cx , dx
cld
strPrtLoop:
lodsb
stosw
call delay
loop strPrtLoop
rubString:
mov ax , 0x0720
mov cx , dx
std
strRubLoop:
stosw
call delay
loop strRubLoop
jmp printString
pop es
pop di
pop si
pop dx
pop cx
pop bx
pop ax
pop bp
ret 4
initializePCB:
push bp
mov bp , sp
push ax
push bx
push cx
push si
mov bx , [nextPCB]
cmp bx , 9
jz
finish
mov cl , 5
shl bx , cl
mov ax , [bp+12] ;read
segment
mov [PCB+bx+18] , ax
mov ax , [bp+10] ;read
offset
mov [PCB+bx+16] , ax
mov [PCB+bx+22] , ds
mov si , [nextPCB]
mov cl , 9
shl si , cl
add si , 256*2+stack
mov ax , [bp+6]
sub si , 2
mov [si] , ax ;x-coord
mov ax , [bp+4]
sub si , 2
mov [si] , ax ;y-coord
mov ax , [bp+8]
sub si , 2
mov [si] , ax ;color/string
sub si , 2
mov [PCB+bx+14] , si
mov word [PCB+bx+26] , 0x200
mov ax , [PCB+28]
mov [PCB+bx+28] , ax
mov ax , [nextPCB]
mov [PCB+28] , ax
inc word [nextPCB]
finish:
pop si
pop cx
pop bx
pop ax
pop bp
ret 10
timer:
push ds
push bx
push cs
pop ds
mov bx , [current]
shl bx , 5
mov [PCB+bx+0] , ax
mov [PCB+bx+4] , cx
mov [PCB+bx+6] , dx
mov [PCB+bx+8] , si
mov [PCB+bx+10] , di
mov [PCB+bx+12] , bp
mov [PCB+bx+24] , es
pop ax
mov [PCB+bx+2] , ax
pop ax
mov [PCB+bx+20] , ax
pop ax
mov [PCB+bx+16] , ax
pop ax
mov [PCB+bx+18] , ax
pop ax
mov [PCB+bx+26] , ax
mov [PCB+bx+22] , ss
mov [PCB+bx+14] , sp
mov bx , [PCB+bx+28]
mov [current] , bx
shl bx , 5
mov cx , [PCB+bx+4]
mov dx , [PCB+bx+6]
mov si , [PCB+bx+8]
mov di , [PCB+bx+10]
mov bp , [PCB+bx+12]
mov es , [PCB+bx+24]
mov ss , [PCB+bx+22]
mov sp , [PCB+bx+14]
push word [PCB+bx+26]
push word [PCB+bx+18]
push word [PCB+bx+16]
push word [PCB+bx+20]
mov al , 0x20
out 0x20 , al
mov ax , [PCB+bx+0]
mov bx , [PCB+bx+2]
pop ds
iret
start:
call
clearScreen
push 0
pop es
cli
mov word [es:8*4] ,
timer
mov [es:8*4+2] , cs
sti
nextKey:
xor ah , ah
int 0x16
push cs
cmpStr:
cmp al , 115
jnz
blue
push stringTask
push string
jmp
proceed
blue:
cmp al , 98
jnz
green
push colorTask
push 0x1020
jmp
proceed
green:
cmp al , 103
jnz
cyan
push colorTask
push 0x2020
jmp
proceed
cyan:
cmp al , 99
jnz
red
push colorTask
push 0x3020
jmp
proceed
red:
cmp al , 114
jnz
magenta
push colorTask
push 0x4020
jmp
proceed
magenta:
cmp al , 109
jnz
orange
push colorTask
push 0x5020
jmp
proceed
orange:
cmp al , 111
jnz
white
push colorTask
push 0x6020
jmp
proceed
white:
cmp al , 119
jnz
nextKey
push colorTask
push 0x7020
proceed:
push word [xPos]
push word [yPos]
call
initializePCB
cmp word [xPos] , 0
jnz
reset
mov word [xPos] , 40
jmp
nextKey
reset:
mov word [xPos] , 0
add word [yPos] , 6
jmp
nextKey
No comments
Post a Comment