WebSVN – Kolibri OS – Blame – /kernel/trunk/core/string.inc

Rev	Author	Line No.	Line
2288	clevermous	1	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
		2	;; ;;
9715	Doczom	3	;; Copyright (C) KolibriOS team 2004-2022. All rights reserved. ;;
2288	clevermous	4	;; Distributed under terms of the GNU General Public License ;;
		5	;; Author: Kees J. Bot 1 Jan 1994 ;;
		6	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
		7
		8	$Revision: 9715 $
		9
		10
		11	; size_t strncat(char s1, const char s2, size_t n)
		12	; Append string s2 to s1.
		13
		14	; char strchr(const char s, int c)
		15
		16
		17	; int strncmp(const char s1, const char s2, size_t n)
		18	; Compare two strings.
		19
		20	; char strncpy(char s1, const char *s2, size_t n)
		21	; Copy string s2 to s1.
		22
		23	; size_t strnlen(const char *s, size_t n)
		24	; Return the length of a string.
		25
		26	; proc strrchr stdcall, s:dword, c:dword
		27	; Look for the last occurrence a character in a string.
		28
		29	proc strncat stdcall, s1:dword, s2:dword, n:dword
		30	push esi
		31	push edi
		32	mov edi, [s1] ; String s1
		33	mov edx, [n] ; Maximum length
		34
		35	mov ecx, -1
		36	xor al, al ; Null byte
		37	cld
		38	repne scasb ; Look for the zero byte in s1
		39	dec edi ; Back one up (and clear 'Z' flag)
		40	push edi ; Save end of s1
		41	mov edi, [s2] ; edi = string s2
		42	mov ecx, edx ; Maximum count
		43	repne scasb ; Look for the end of s2
		44	jne @F
		45	inc ecx ; Exclude null byte
		46	@@:
		47	sub edx, ecx ; Number of bytes in s2
		48	mov ecx, edx
		49	mov esi, [s2] ; esi = string s2
		50	pop edi ; edi = end of string s1
		51	rep movsb ; Copy bytes
		52	stosb ; Add a terminating null
		53	mov eax, [s1] ; Return s1
		54	pop edi
		55	pop esi
		56	ret
		57	endp
		58
		59	align 4
		60	proc strncmp stdcall, s1:dword, s2:dword, n:dword
		61
		62	push esi
		63	push edi
		64	mov ecx, [n]
		65	test ecx, ecx ; Max length is zero?
		66	je .done
		67
		68	mov esi, [s1] ; esi = string s1
		69	mov edi, [s2] ; edi = string s2
		70	cld
		71	.compare:
		72	cmpsb ; Compare two bytes
		73	jne .done
		74	cmp byte [esi-1], 0 ; End of string?
		75	je .done
		76	dec ecx ; Length limit reached?
		77	jne .compare
		78	.done:
		79	seta al ; al = (s1 > s2)
		80	setb ah ; ah = (s1 < s2)
		81	sub al, ah
		82	movsx eax, al ; eax = (s1 > s2) - (s1 < s2), i.e. -1, 0, 1
		83	pop edi
		84	pop esi
		85	ret
		86	endp
		87
		88	align 4
		89	proc strncpy stdcall, s1:dword, s2:dword, n:dword
		90
		91	push esi
		92	push edi
		93
		94	mov ecx, [n] ; Maximum length
		95	mov edi, [s2] ; edi = string s2
		96	xor al, al ; Look for a zero byte
		97	mov edx, ecx ; Save maximum count
		98	cld
		99	repne scasb ; Look for end of s2
		100	sub edx, ecx ; Number of bytes in s2 including null
		101	xchg ecx, edx
		102	mov esi, [s2] ; esi = string s2
		103	mov edi, [s1] ; edi = string s1
		104	rep movsb ; Copy bytes
		105
		106	mov ecx, edx ; Number of bytes not copied
		107	rep stosb ; strncpy always copies n bytes by null padding
		108	mov eax, [s1] ; Return s1
		109	pop edi
		110	pop esi
		111	ret
		112	endp
		113
		114	align 4
		115	proc strnlen stdcall, s:dword, n:dword
		116
		117	push edi
6318	serge	118	mov ecx, [n]
2288	clevermous	119	mov edi, [s] ; edi = string
		120	xor al, al ; Look for a zero byte
		121	mov edx, ecx ; Save maximum count
		122	cmp cl, 1 ; 'Z' bit must be clear if ecx = 0
		123	cld
		124	repne scasb ; Look for zero
		125	jne @F
		126	inc ecx ; Don't count zero byte
		127	@@:
		128	mov eax, edx
		129	sub eax, ecx ; Compute bytes scanned
		130	pop edi
		131	ret
		132	endp
		133
		134	align 4
		135	proc strchr stdcall, s:dword, c:dword
		136	push edi
		137	cld
		138	mov edi, [s] ; edi = string
		139	mov edx, 16 ; Look at small chunks of the string
		140	.next:
		141	shl edx, 1 ; Chunks become bigger each time
		142	mov ecx, edx
		143	xor al, al ; Look for the zero at the end
		144	repne scasb
		145	pushf ; Remember the flags
		146	sub ecx, edx
		147	neg ecx ; Some or all of the chunk
		148	sub edi, ecx ; Step back
		149	mov eax, [c] ; The character to look for
		150	repne scasb
		151	je .found
		152	popf ; Did we find the end of string earlier?
		153	jne .next ; No, try again
		154	xor eax, eax ; Return NULL
		155	pop edi
		156	ret
		157	.found:
		158	pop eax ; Get rid of those flags
		159	lea eax, [edi-1] ; Address of byte found
		160	pop edi
		161	ret
		162
		163	endp
		164
		165
		166	proc strrchr stdcall, s:dword, c:dword
		167	push edi
		168	mov edi, [s] ; edi = string
		169	mov ecx, -1
		170	xor al, al
		171	cld
		172	repne scasb ; Look for the end of the string
		173	not ecx ; -1 - ecx = Length of the string + null
		174	dec edi ; Put edi back on the zero byte
		175	mov eax, [c] ; The character to look for
		176	std ; Downwards search
		177	repne scasb
		178	cld ; Direction bit back to default
		179	jne .fail
		180	lea eax, [edi+1] ; Found it
		181	pop edi
		182	ret
		183	.fail:
		184	xor eax, eax ; Not there
		185	pop edi
		186	ret
		187	endp
		188

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