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page ,132
title strnset - set first n characters to one char.
;***
;strnset.asm - set first n characters to single character
;
; Copyright (c) 1985-1991, Microsoft Corporation. All rights reserved.
;
;Purpose:
; defines _strnset() - sets at most the first n characters of a string
; to a given character.
;
;Revision History:
; 11-18-83 RN initial version
; 05-18-88 SJM Add model-independent (large model) ifdef
; 05-23-88 WAJ If count = strlen(string)+1 then strlen+1 bytes were set.
; 08-04-88 SJM convert to cruntime/ add 32-bit support
; 08-23-88 JCR 386 cleanup
; 10-26-88 JCR General cleanup for 386-only code
; 03-23-90 GJF Changed to _stdcall. Also, fixed the copyright.
; 01-18-91 GJF ANSI naming.
; 05-10-91 GJF Back to _cdecl, sigh...
;
;*******************************************************************************
.xlist
include cruntime.inc
.list
page
;***
;char *_strnset(string, val, count) - set at most count characters to val
;
;Purpose:
; Sets the first count characters of string the character value.
; If the length of string is less than count, the length of
; string is used in place of n.
;
; Algorithm:
; char *
; _strnset (string, val, count)
; char *string,val;
; unsigned int count;
; {
; char *start = string;
;
; while (count-- && *string)
; *string++ = val;
; return(start);
; }
;
;Entry:
; char *string - string to set characters in
; char val - character to fill with
; unsigned count - count of characters to fill
;
;Exit:
; returns string, now filled with count copies of val.
;
;Uses:
;
;Exceptions:
;
;*******************************************************************************
CODESEG
public _strnset
_strnset proc \
uses edi ebx, \
string:ptr byte, \
val:byte, \
count:IWORD
mov edi,[string] ; di = string
mov edx,edi ; dx=string addr; save return value
mov ebx,[count] ; cx = max chars to set
xor eax,eax ; null byte
mov ecx,ebx
jecxz short done ; zero length specified
repne scasb ; find null byte & count bytes in cx
jne short nonull ; null not found
inc ecx ; don't want the null
nonull:
sub ebx,ecx ; bx=strlen (not null)
mov ecx,ebx ; cx=strlen (not null)
mov edi,edx ; restore string pointer
mov al,val ; byte value
rep stosb ; fill 'er up
done:
mov eax,edx ; return value: string addr
ifdef _STDCALL_
ret DPSIZE + 2*ISIZE ; _stdcall return
else
ret ; _cdecl return
endif
_strnset endp
end
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