For-loops:
For-loop in C:
for(int x = 0; x<=3; x++)
{
//Do something!
}
The same loop in 8086 assembler:
xor cx,cx ; cx-register is the counter, set to 0
loop1 nop ; Whatever you wanna do goes here, should not change cx
inc cx ; Increment
cmp cx,3 ; Compare cx to the limit
jle loop1 ; Loop while less or equal
That is the loop if you need to access your index (cx). If you just wanna to something 0-3=4 times but you do not need the index, this would be easier:
mov cx,4 ; 4 iterations
loop1 nop ; Whatever you wanna do goes here, should not change cx
loop loop1 ; loop instruction decrements cx and jumps to label if not 0
If you just want to perform a very simple instruction a constant amount of times, you could also use an assembler-directive which will just hardcore that instruction
times 4 nop
Do-while-loops
Do-while-loop in C:
int x=1;
do{
//Do something!
}
while(x==1)
The same loop in assembler:
mov ax,1
loop1 nop ; Whatever you wanna do goes here
cmp ax,1 ; Check wether cx is 1
je loop1 ; And loop if equal
While-loops
While-loop in C:
while(x==1){
//Do something
}
The same loop in assembler:
jmp loop1 ; Jump to condition first
cloop1 nop ; Execute the content of the loop
loop1 cmp ax,1 ; Check the condition
je cloop1 ; Jump to content of the loop if met
For the for-loops you should take the cx-register because it is pretty much standard. For the other loop conditions you can take a register of your liking. Of course replace the no-operation instruction with all the instructions you wanna perform in the loop.
Do{
AX = 0
AX = AX + 5
BX = 0
BX= BX+AX
} While( AX != BX)
Do while loop always checks the loop the condition at the end of each iteration.