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

Rev	Author	Line No.	Line
2288	clevermous	1	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
		2	;; ;;
10051	ace_dent	3	;; Copyright (C) KolibriOS team 2004-2024. 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
		9	; size_t strncat(char s1, const char s2, size_t n)
		10	; Append string s2 to s1.
		11
		12	; char strchr(const char s, int c)
		13
		14
		15	; int strncmp(const char s1, const char s2, size_t n)
		16	; Compare two strings.
		17
		18	; char strncpy(char s1, const char *s2, size_t n)
		19	; Copy string s2 to s1.
		20
		21	; size_t strnlen(const char *s, size_t n)
		22	; Return the length of a string.
		23
		24	; proc strrchr stdcall, s:dword, c:dword
		25	; Look for the last occurrence a character in a string.
		26
		27	proc strncat stdcall, s1:dword, s2:dword, n:dword
		28	push esi
		29	push edi
		30	mov edi, [s1] ; String s1
		31	mov edx, [n] ; Maximum length
		32
		33	mov ecx, -1
		34	xor al, al ; Null byte
		35	cld
		36	repne scasb ; Look for the zero byte in s1
		37	dec edi ; Back one up (and clear 'Z' flag)
		38	push edi ; Save end of s1
		39	mov edi, [s2] ; edi = string s2
		40	mov ecx, edx ; Maximum count
		41	repne scasb ; Look for the end of s2
		42	jne @F
		43	inc ecx ; Exclude null byte
		44	@@:
		45	sub edx, ecx ; Number of bytes in s2
		46	mov ecx, edx
		47	mov esi, [s2] ; esi = string s2
		48	pop edi ; edi = end of string s1
		49	rep movsb ; Copy bytes
		50	stosb ; Add a terminating null
		51	mov eax, [s1] ; Return s1
		52	pop edi
		53	pop esi
		54	ret
		55	endp
		56
		57	align 4
		58	proc strncmp stdcall, s1:dword, s2:dword, n:dword
		59
		60	push esi
		61	push edi
		62	mov ecx, [n]
		63	test ecx, ecx ; Max length is zero?
		64	je .done
		65
		66	mov esi, [s1] ; esi = string s1
		67	mov edi, [s2] ; edi = string s2
		68	cld
		69	.compare:
		70	cmpsb ; Compare two bytes
		71	jne .done
		72	cmp byte [esi-1], 0 ; End of string?
		73	je .done
		74	dec ecx ; Length limit reached?
		75	jne .compare
		76	.done:
		77	seta al ; al = (s1 > s2)
		78	setb ah ; ah = (s1 < s2)
		79	sub al, ah
		80	movsx eax, al ; eax = (s1 > s2) - (s1 < s2), i.e. -1, 0, 1
		81	pop edi
		82	pop esi
		83	ret
		84	endp
		85
		86	align 4
		87	proc strncpy stdcall, s1:dword, s2:dword, n:dword
		88
		89	push esi
		90	push edi
		91
		92	mov ecx, [n] ; Maximum length
		93	mov edi, [s2] ; edi = string s2
		94	xor al, al ; Look for a zero byte
		95	mov edx, ecx ; Save maximum count
		96	cld
		97	repne scasb ; Look for end of s2
		98	sub edx, ecx ; Number of bytes in s2 including null
		99	xchg ecx, edx
		100	mov esi, [s2] ; esi = string s2
		101	mov edi, [s1] ; edi = string s1
		102	rep movsb ; Copy bytes
		103
		104	mov ecx, edx ; Number of bytes not copied
		105	rep stosb ; strncpy always copies n bytes by null padding
		106	mov eax, [s1] ; Return s1
		107	pop edi
		108	pop esi
		109	ret
		110	endp
		111
		112	align 4
		113	proc strnlen stdcall, s:dword, n:dword
		114
		115	push edi
6318	serge	116	mov ecx, [n]
2288	clevermous	117	mov edi, [s] ; edi = string
		118	xor al, al ; Look for a zero byte
		119	mov edx, ecx ; Save maximum count
		120	cmp cl, 1 ; 'Z' bit must be clear if ecx = 0
		121	cld
		122	repne scasb ; Look for zero
		123	jne @F
		124	inc ecx ; Don't count zero byte
		125	@@:
		126	mov eax, edx
		127	sub eax, ecx ; Compute bytes scanned
		128	pop edi
		129	ret
		130	endp
		131
		132	align 4
		133	proc strchr stdcall, s:dword, c:dword
		134	push edi
		135	cld
		136	mov edi, [s] ; edi = string
		137	mov edx, 16 ; Look at small chunks of the string
		138	.next:
		139	shl edx, 1 ; Chunks become bigger each time
		140	mov ecx, edx
		141	xor al, al ; Look for the zero at the end
		142	repne scasb
		143	pushf ; Remember the flags
		144	sub ecx, edx
		145	neg ecx ; Some or all of the chunk
		146	sub edi, ecx ; Step back
		147	mov eax, [c] ; The character to look for
		148	repne scasb
		149	je .found
		150	popf ; Did we find the end of string earlier?
		151	jne .next ; No, try again
		152	xor eax, eax ; Return NULL
		153	pop edi
		154	ret
		155	.found:
		156	pop eax ; Get rid of those flags
		157	lea eax, [edi-1] ; Address of byte found
		158	pop edi
		159	ret
		160
		161	endp
		162
		163
		164	proc strrchr stdcall, s:dword, c:dword
		165	push edi
		166	mov edi, [s] ; edi = string
		167	mov ecx, -1
		168	xor al, al
		169	cld
		170	repne scasb ; Look for the end of the string
		171	not ecx ; -1 - ecx = Length of the string + null
		172	dec edi ; Put edi back on the zero byte
		173	mov eax, [c] ; The character to look for
		174	std ; Downwards search
		175	repne scasb
		176	cld ; Direction bit back to default
		177	jne .fail
		178	lea eax, [edi+1] ; Found it
		179	pop edi
		180	ret
		181	.fail:
		182	xor eax, eax ; Not there
		183	pop edi
		184	ret
		185	endp
		186

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