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strcpy_naive.S revision 1.5 
      1 /*-
      2  * Copyright (c) 2013 The NetBSD Foundation, Inc.
      3  * All rights reserved.
      4  *
      5  * This code is derived from software contributed to The NetBSD Foundation
      6  * by Matt Thomas of 3am Software Foundry.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     18  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     19  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     20  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     21  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     22  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     23  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     24  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     25  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     26  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     27  * POSSIBILITY OF SUCH DAMAGE.
     28  */
     29 #include <machine/asm.h>
     30 
     31 RCSID("$NetBSD: strcpy_naive.S,v 1.5 2017/01/13 13:14:54 christos Exp $")
     32 
     33 #ifdef _LIBC
     34 #ifdef STRLCPY
     35 WEAK_ALIAS(strlcpy, _strlcpy)
     36 #endif
     37 #endif
     38 
     39 /*
     40  * These are "naive" versions of the str*cpy routines designed to be simple
     41  * and small.
     42  */
     43 
     44 #if defined(STRLCPY)
     45 /* LINTSTUB: size_t strlcpy(char *, const char *, size_t) */
     46 ENTRY(_strlcpy)
     47 	add	ip, r1, #1		/* save src pointer (+ NUL) */
     48 	subs	r2, r2, #1		/* make sure there's room for a NUL */
     49 	blt	3f			/*   no room, do the strlen */
     50 	add	r2, r2, r0		/* get end of dst */
     51 1:	cmp	r0, r2			/* room for another char? */
     52 	beq	2f			/*   no, write NUL and do the strlen */
     53 	ldrb	r3, [r1], #1		/* read a byte */
     54 	strb	r3, [r0], #1		/* write a byte */
     55 	teq	r3, #0			/* was it a NUL? */
     56 	bne	1b			/*   no, do next byte */
     57 	b	4f			/*   yes, end of string, so return */
     58 2:	mov	r3, #0			/* NUL */
     59 	strb	r3, [r0]		/* write to end of string */
     60 3:	ldrb	r3, [r1], #1		/* read a byte */
     61 	teq	r3, #0			/* was it a NUL? */
     62 	bne	3b			/*   no, get next byte */
     63 4:	sub	r0, r1, ip 		/* return length of src string */
     64 	RET
     65 END(_strlcpy)
     66 #elif defined(STRNCPY)
     67 /* LINTSTUB: char * strncpy(char *, const char *, size_t) */
     68 ENTRY(_strncpy)
     69 	mov	ip, r0			/* we want to preserve r0 */
     70 	add	r2, r2, r0		/* get end of dst buffer */
     71 1:	cmp	ip, r2			/* are at the end of dst already? */
     72 	RETc(eq)			/*   yes, just return. */
     73 	ldrb	r3, [r1], #1		/* read a byte */
     74 	strb	r3, [ip], #1		/* write a byte */
     75 	teq	r3, #0			/* was it a NUL? */
     76 	bne	1b			/*   no, try next byte */
     77 2:	cmp	ip, r2			/* are at the end of dst already? */
     78 	strblt	r3, [ip], #1		/*   no, write a NUL */
     79 	blt	2b			/*       until dst is filled */
     80 3:	RET				/* return dst pointer */
     81 END(_strncpy)
     82 #else
     83 /* LINTSTUB: char * strcpy(char *, const char *) */
     84 ENTRY(_strcpy)
     85 	mov	ip, r0			/* we want to preserve r0 */
     86 1:	ldrb	r3, [r1], #1		/* read a byte */
     87 	strb	r3, [ip], #1		/* write a byte */
     88 	teq	r3, #0			/* was it a NUL? */
     89 	bne	1b			/*   no, try next byte */
     90 	RET				/* return dst pointer */
     91 END(_strcpy)
     92 #endif
     93