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Tech Arsenal 1
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strlibs.zip
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STRNLEN.ASM
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Assembly Source File
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1993-01-04
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1KB
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55 lines
; Static Name Aliases
;
TITLE strnlen
; NAME strnlen.C
; int strnlen(src, len)
; returns the number of characters up to the first NUL in src, or len,
; whichever is smaller.
.287
_TEXT SEGMENT BYTE PUBLIC 'CODE'
_TEXT ENDS
_DATA SEGMENT WORD PUBLIC 'DATA'
_DATA ENDS
CONST SEGMENT WORD PUBLIC 'CONST'
CONST ENDS
_BSS SEGMENT WORD PUBLIC 'BSS'
_BSS ENDS
DGROUP GROUP CONST, _BSS, _DATA
ASSUME CS: _TEXT, DS: DGROUP, SS: DGROUP, ES: DGROUP
EXTRN __chkstk:NEAR
_TEXT SEGMENT
PUBLIC _strnlen
_strnlen PROC NEAR
push bp
mov bp,sp
push si
; s = 4
; register si = s
; n = 6
; register cx = n
; L = ax
mov si,[bp+4] ;s
mov cx,[bp+6] ;n
xor bx,bx ;L
$cmp:
jcxz cleanup
cmp BYTE PTR [si][bx],0
je cleanup
dec cx
inc bx ;L
jmp $cmp
cleanup:
xchg ax,bx
pop si
mov sp,bp
pop bp
ret
_strnlen ENDP
_TEXT ENDS
END