String length: Difference between revisions

=={{header|8086 Assembly}}==

{{trans|68000 Assembly}}

===Byte Length===

<lang asm>;INPUT: DS:SI = BASE ADDR. OF STRING

;TYPICALLY, MS-DOS USES $ TO TERMINATE STRINGS.

GetStringLength:

xor cx,cx ;this takes fewer bytes to encode than "mov cx,0"

cld ;makes string functions post-inc rather than post-dec.

loop_GetStringLength:

lodsb ;equivalent of "mov al,[ds:si],inc si" except this doesn't alter the flags.

cmp '$'

je done ;if equal, we're finished.

inc cx ;add 1 to length counter. A null string will have a length of zero.

jmp loop_GetStringLength

done:

ret