Category : Assembly Language Source Code
Archive   : RHSTDLIB.ZIP
Filename : STRCSPAN.ASM

stdlib segment para public 'slcode'
assume cs:stdlib
;
;
; strcspan- Returns the number of characters at the beginning of a string
; which are NOT from a specified set.
;
; inputs:
;
; ES:DI- Points at string to test.
; DX:SI- Points at set of characters (zero terminated string).
;
; outputs:
;
; CX- Number of characters not in the set which are the prefix of
; the test string.
;
;
;
;
public sl_strcspan
;
sl_strcspan proc far
pushf
push es
push ds
push ax
push bx
push dx
push si
push di
cld
;
mov ax, es
mov es, dx
mov ds, ax
xchg si, di
;
mov bx, di ;Preserve ptr to char set.
mov cx, 0ffffh
mov al, 0
repne scasb ;Compute length of char set.
neg cx
dec cx
dec cx
mov dx, cx ;Save for use later.
;
; Okay, now we can see how many characters from the set match the prefix
; characters in the string.
;
StrLp: lodsb ;Get next char in string.
mov cx, dx ;Get length of char set.
mov di, bx ;Get ptr to char set
repne scasb ;See if in set
jnz StrLp ;Repeat while not in set.
;
pop di
mov cx, di
sub cx, si
neg cx
dec cx
pop si
pop dx
pop bx
pop ax
pop ds
pop es
popf
ret
sl_strcspan endp
;
;
;
;
stdlib ends
end