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page ,132
title strrchr - find last occurence of character in string
;***
;strrchr.asm - find last occurrence of character in string
;
; Copyright (c) 1985-1991, Microsoft Corporation. All rights reserved.
;
;Purpose:
; defines strrchr() - find the last occurrence of a given character
; in a string.
;
;Revision History:
; 10-27-83 RN initial version
; 05-18-88 SJM Add model-independent (large model) ifdef
; 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
; 03-26-90 GJF Changed to _stdcall. Also, fixed the copyright.
; 05-10-91 GJF Back to _cdecl, sigh...
;
;*******************************************************************************
.xlist
include cruntime.inc
.list
page
;***
;char *strrchr(string, ch) - find last occurrence of ch in string
;
;Purpose:
; Finds the last occurrence of ch in string. The terminating
; null character is used as part of the search.
;
; Algorithm:
; char *
; strrchr (string, ch)
; char *string, ch;
; {
; char *start = string;
;
; while (*string++)
; ;
; while (--string != start && *string != ch)
; ;
; if (*string == ch)
; return(string);
; return(NULL);
; }
;
;Entry:
; char *string - string to search in
; char ch - character to search for
;
;Exit:
; returns a pointer to the last occurrence of ch in the given
; string
; returns NULL if ch does not occurr in the string
;
;Uses:
;
;Exceptions:
;
;*******************************************************************************
CODESEG
public strrchr
strrchr proc \
uses edi, \
string:ptr byte, \
chr:byte
mov edi,[string] ; di = string
xor eax,eax ; al=null byte
or ecx,-1 ; cx = -1
repne scasb ; find the null & count bytes
inc ecx ; cx=-byte count (with null)
neg ecx ; cx=+byte count (with null)
dec edi ; di points to terminal null
mov al,chr ; al=search byte
std ; count 'down' on string this time
repne scasb ; find that byte
inc edi ; di points to byte which stopped scan
cmp [edi],al ; see if we have a hit
je short returndi ; yes, point to byte
xor eax,eax ; no, return NULL
jmp short toend ; do return sequence
returndi:
mov eax,edi ; ax=pointer to byte
toend:
cld
ifdef _STDCALL_
ret DPSIZE + ISIZE ; _stdcall return
else
ret ; _cdecl return
endif
strrchr endp
end
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