Assembly x86 Delay loop - loops

Question

hi i made program that will rotate two symbols - \ and / but i dont know how to set cx counter in nested loops can someone give me advice or help me ?
here is the code of that part
program:
mov ah, 0fh ; function - get video mode
int 10h
push ax ; save number of columns
push bx ; save page number
mov ah, 0 ; function - set video mode
int 10h
mov al, 0003h ;set video mode
int 10h
mov cx,10d ; Outer loop counter how many symbols rotate
mov bx,50d ; this is for delay loop
OuterLoop:
push cx
mov ah,02h
mov bh, 0 ;cursor set
mov dh, 2
mov dl, 10
int 10h
mov AH,0Ah
mov al,"/" symbol /
mov bh,0
mov cx,1
int 10h
mov cx,bx
call Delay ;delay loop
sub bx,15d
mov ah,02h
mov bh, 0
mov dh, 2 cursor set
mov dl, 10
int 10h
mov AH,0Ah
mov al,"\" ;symbol \
mov bh,0
mov cx,1
int 10h
mov cx,bx
call Delay ; another delay
sub bx,10
pop cx ; Restore current CX
loop OuterLoop
jmp START ; and after end it should jump to start where is menu with choices
it should work like this
write /
delay for example 10 sec
write \
delay 8 sec
and jump to beginning and loop
thanks for advices
this is my delay procedure
Delay PROC NEAR ;
push ds ;
push si ;
push ax ;
xor ax, ax ;AX = 0
mov ds, ax ;DS = 0
mov si, 046Ch ;
t1: mov ax, [si] ;
t2: cmp ax, [si] ;
je t2 ;
loop t1 ;
pop ax ;
pop si ;
pop ds ;
ret ;
Delay ENDP ;
i am still working on this app but it is not working all i need is this steps to be made
program : start of loop
\
delay delay 100 times
/
delay delay 80 times
loop
and after every loop to decrease delay like this 100 times 80,60,40 and so on but i dont know where to put push and pop cx because my delay procedure is working with cx. i just set cx for example to 100 and it makes delay and so on.

Answer 1

I see two problems:
First, bx is initialized here
mov bx,50d ; this is for delay loop
but then it gets over-written by
mov bh, 0
bh is bits 15:8 of bx
Second, in the Delay procedure, what modifies the location at [si] so that the je t2 branch falls thru? As it stands that is an infinite loop:
xor ax, ax ;AX = 0
mov ds, ax ;DS = 0
mov si, 046Ch ;
t1: mov ax, [si] ;
t2: cmp ax, [si] ;
je t2 ;
loop t1 ;
Update:
I found that address 0x46c is a BIOS address that contains time information.
http://www.osdata.com/system/physical/lowmem.htm
So the memory you are watching in that loop is a location updated by BIOS with a counter of timer ticks (counts every 54.9 milliseconds), see
http://code.google.com/p/xtideuniversalbios/source/browse/trunk/Assembly_Library/Src/Time/TimerTicks.asm?spec=svn131&r=131
So to answer your question, before calling your Delay procedure you should load CX with the count of BIOS ticks you wish to delay (time in milliseconds divided by 54.9).

Answer 2

For to drawing my own cursor i use the timer interrupt for to become a more steady delay on different performant CPUs.
Cursor_Speed = 7
;-------------DATA--------------------------------------
CURFLAG DB 0, 0, 0, 0
ALTVEC DD 0
;-------------CODE--------------------------------------
cli
xor ax, ax
mov es, ax
mov ebx, DWORD PTR es:[8*4] ; Get the old Vector (Offset/Segment)
mov DWORD PTR[ALTVEC], ebx ; save it
mov cs:DWORD PTR[OLDVEC], ebx
mov es:[8*4], OFFSET NEWVEC ; Set the new IRQ-Vector
mov es:[(8*4)+2], cs
mov al, 36h ; Set 18,2 Hertz(Standard)
out 43h, al
xor al, al
out 40h, al ; low
out 40h, al ; high
sti
;---------------------------------------------------
......
;---------------------------------------------------
NEWVEC: inc BYTE PTR[CURFLAG+1]
cmp BYTE PTR[CURFLAG+1], Cursor_Speed
jb short NOHIT
mov BYTE PTR[CURFLAG+1], 0
xor BYTE PTR[CURFLAG], 1
NOHIT: DB 0EAh ; jmp far
OLDVEC DD 0
;---------------------------------------------------
....
Alternativly we can wait of the vsinc with polling port 3DAh for to become a little bit lesser precice delay.
Dirk