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;; ;;
;; Copyright (C) KolibriOS team 2004-2011. All rights reserved. ;;
;; Distributed under terms of the GNU General Public License ;;
;; Author: Kees J. Bot 1 Jan 1994 ;;
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$Revision: 2455 $
; size_t strncat(char *s1, const char *s2, size_t n)
; Append string s2 to s1.
; char *strchr(const char *s, int c)
; int strncmp(const char *s1, const char *s2, size_t n)
; Compare two strings.
; char *strncpy(char *s1, const char *s2, size_t n)
; Copy string s2 to s1.
; size_t strnlen(const char *s, size_t n)
; Return the length of a string.
; proc strrchr stdcall, s:dword, c:dword
; Look for the last occurrence a character in a string.
proc strncat stdcall, s1:dword, s2:dword, n:dword
push esi
push edi
mov edi, [s1] ; String s1
mov edx, [n] ; Maximum length
mov ecx, -1
xor al, al ; Null byte
cld
repne scasb ; Look for the zero byte in s1
dec edi ; Back one up (and clear 'Z' flag)
push edi ; Save end of s1
mov edi, [s2] ; edi = string s2
mov ecx, edx ; Maximum count
repne scasb ; Look for the end of s2
jne @F
inc ecx ; Exclude null byte
@@:
sub edx, ecx ; Number of bytes in s2
mov ecx, edx
mov esi, [s2] ; esi = string s2
pop edi ; edi = end of string s1
rep movsb ; Copy bytes
stosb ; Add a terminating null
mov eax, [s1] ; Return s1
pop edi
pop esi
ret
endp
align 4
proc strncmp stdcall, s1:dword, s2:dword, n:dword
push esi
push edi
mov ecx, [n]
test ecx, ecx ; Max length is zero?
je .done
mov esi, [s1] ; esi = string s1
mov edi, [s2] ; edi = string s2
cld
.compare:
cmpsb ; Compare two bytes
jne .done
cmp byte [esi-1], 0 ; End of string?
je .done
dec ecx ; Length limit reached?
jne .compare
.done:
seta al ; al = (s1 > s2)
setb ah ; ah = (s1 < s2)
sub al, ah
movsx eax, al ; eax = (s1 > s2) - (s1 < s2), i.e. -1, 0, 1
pop edi
pop esi
ret
endp
align 4
proc strncpy stdcall, s1:dword, s2:dword, n:dword
push esi
push edi
mov ecx, [n] ; Maximum length
mov edi, [s2] ; edi = string s2
xor al, al ; Look for a zero byte
mov edx, ecx ; Save maximum count
cld
repne scasb ; Look for end of s2
sub edx, ecx ; Number of bytes in s2 including null
xchg ecx, edx
mov esi, [s2] ; esi = string s2
mov edi, [s1] ; edi = string s1
rep movsb ; Copy bytes
mov ecx, edx ; Number of bytes not copied
rep stosb ; strncpy always copies n bytes by null padding
mov eax, [s1] ; Return s1
pop edi
pop esi
ret
endp
align 4
proc strnlen stdcall, s:dword, n:dword
push edi
mov edi, [s] ; edi = string
xor al, al ; Look for a zero byte
mov edx, ecx ; Save maximum count
cmp cl, 1 ; 'Z' bit must be clear if ecx = 0
cld
repne scasb ; Look for zero
jne @F
inc ecx ; Don't count zero byte
@@:
mov eax, edx
sub eax, ecx ; Compute bytes scanned
pop edi
ret
endp
align 4
proc strchr stdcall, s:dword, c:dword
push edi
cld
mov edi, [s] ; edi = string
mov edx, 16 ; Look at small chunks of the string
.next:
shl edx, 1 ; Chunks become bigger each time
mov ecx, edx
xor al, al ; Look for the zero at the end
repne scasb
pushf ; Remember the flags
sub ecx, edx
neg ecx ; Some or all of the chunk
sub edi, ecx ; Step back
mov eax, [c] ; The character to look for
repne scasb
je .found
popf ; Did we find the end of string earlier?
jne .next ; No, try again
xor eax, eax ; Return NULL
pop edi
ret
.found:
pop eax ; Get rid of those flags
lea eax, [edi-1] ; Address of byte found
pop edi
ret
endp
proc strrchr stdcall, s:dword, c:dword
push edi
mov edi, [s] ; edi = string
mov ecx, -1
xor al, al
cld
repne scasb ; Look for the end of the string
not ecx ; -1 - ecx = Length of the string + null
dec edi ; Put edi back on the zero byte
mov eax, [c] ; The character to look for
std ; Downwards search
repne scasb
cld ; Direction bit back to default
jne .fail
lea eax, [edi+1] ; Found it
pop edi
ret
.fail:
xor eax, eax ; Not there
pop edi
ret
endp