[apple/xnu.git] / libsyscall / wrappers / memcpy.c

/*-
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "string.h"

/*
 * sizeof(word) MUST BE A POWER OF TWO
 * SO THAT wmask BELOW IS ALL ONES
 */
typedef	int word;		/* "word" used for optimal copy speed */

#define	wsize	sizeof(word)
#define	wmask	(wsize - 1)

/*
 * Copy a block of memory, handling overlap.
 * This is the routine that actually implements
 * (the portable versions of) bcopy, memcpy, and memmove.
 */

__private_extern__
void * memcpy(void *dst0, const void *src0, size_t length)
{
	char *dst = dst0;
	const char *src = src0;
	size_t t;
	
	if (length == 0 || dst == src)		/* nothing to do */
		goto done;
	
	/*
	 * Macros: loop-t-times; and loop-t-times, t>0
	 */
#define	TLOOP(s) if (t) TLOOP1(s)
#define	TLOOP1(s) do { s; } while (--t)
	
	if ((unsigned long)dst < (unsigned long)src) {
		/*
		 * Copy forward.
		 */
		t = (uintptr_t)src;	/* only need low bits */
		if ((t | (uintptr_t)dst) & wmask) {
			/*
			 * Try to align operands.  This cannot be done
			 * unless the low bits match.
			 */
			if ((t ^ (uintptr_t)dst) & wmask || length < wsize)
				t = length;
			else
				t = wsize - (t & wmask);
			length -= t;
			TLOOP1(*dst++ = *src++);
		}
		/*
		 * Copy whole words, then mop up any trailing bytes.
		 */
		t = length / wsize;
		TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
		t = length & wmask;
		TLOOP(*dst++ = *src++);
	} else {
		/*
		 * Copy backwards.  Otherwise essentially the same.
		 * Alignment works as before, except that it takes
		 * (t&wmask) bytes to align, not wsize-(t&wmask).
		 */
		src += length;
		dst += length;
		t = (uintptr_t)src;
		if ((t | (uintptr_t)dst) & wmask) {
			if ((t ^ (uintptr_t)dst) & wmask || length <= wsize)
				t = length;
			else
				t &= wmask;
			length -= t;
			TLOOP1(*--dst = *--src);
		}
		t = length / wsize;
		TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
		t = length & wmask;
		TLOOP(*--dst = *--src);
	}
done:
	return (dst0);
}

__private_extern__ void *
memmove(void *s1, const void *s2, size_t n)
{
	return memcpy(s1, s2, n);
}

__private_extern__ void
bcopy(const void *s1, void *s2, size_t n)
{
	memcpy(s2, s1, n);
}

/*
 * Compare memory regions.
 */
__private_extern__ int
memcmp(const void *s1, const void *s2, size_t n)
{
	if (n != 0) {
		const unsigned char *p1 = s1, *p2 = s2;

		do {
			if (*p1++ != *p2++)
				return (*--p1 - *--p2);
		} while (--n != 0);
	}
	return (0);
}
Commit	Line	Data
6d2010ae A	1	/*-
	2	* Copyright (c) 1990, 1993
	3	* The Regents of the University of California. All rights reserved.
	4	*
	5	* This code is derived from software contributed to Berkeley by
	6	* Chris Torek.
	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	* 4. Neither the name of the University nor the names of its contributors
	17	* may be used to endorse or promote products derived from this software
	18	* without specific prior written permission.
	19	*
	20	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	* SUCH DAMAGE.
	31	*/
	32
	33	#include "string.h"
	34
	35	/*
	36	* sizeof(word) MUST BE A POWER OF TWO
	37	* SO THAT wmask BELOW IS ALL ONES
	38	*/
	39	typedef int word; /* "word" used for optimal copy speed */
	40
	41	#define wsize sizeof(word)
	42	#define wmask (wsize - 1)
	43
	44	/*
	45	* Copy a block of memory, handling overlap.
	46	* This is the routine that actually implements
	47	* (the portable versions of) bcopy, memcpy, and memmove.
	48	*/
	49
	50	__private_extern__
	51	void * memcpy(void dst0, const void src0, size_t length)
	52	{
	53	char *dst = dst0;
	54	const char *src = src0;
	55	size_t t;
	56
	57	if (length == 0 \|\| dst == src) /* nothing to do */
	58	goto done;
	59
	60	/*
	61	* Macros: loop-t-times; and loop-t-times, t>0
	62	*/
	63	#define TLOOP(s) if (t) TLOOP1(s)
	64	#define TLOOP1(s) do { s; } while (--t)
65
66	if ((unsigned long)dst < (unsigned long)src) {
67	/*
68	* Copy forward.
69	*/
70	t = (uintptr_t)src; /* only need low bits */
71	if ((t \| (uintptr_t)dst) & wmask) {
72	/*
73	* Try to align operands. This cannot be done
74	* unless the low bits match.
75	*/
76	if ((t ^ (uintptr_t)dst) & wmask \|\| length < wsize)
77	t = length;
78	else
79	t = wsize - (t & wmask);
80	length -= t;
81	TLOOP1(dst++ = src++);
82	}
83	/*
84	* Copy whole words, then mop up any trailing bytes.
85	*/
86	t = length / wsize;
87	TLOOP((word )dst = (word )src; src += wsize; dst += wsize);
88	t = length & wmask;
89	TLOOP(dst++ = src++);
90	} else {
91	/*
92	* Copy backwards. Otherwise essentially the same.
93	* Alignment works as before, except that it takes
94	* (t&wmask) bytes to align, not wsize-(t&wmask).
95	*/
96	src += length;
97	dst += length;
98	t = (uintptr_t)src;
99	if ((t \| (uintptr_t)dst) & wmask) {
100	if ((t ^ (uintptr_t)dst) & wmask \|\| length <= wsize)
101	t = length;
102	else
103	t &= wmask;
104	length -= t;
105	TLOOP1(--dst = --src);
106	}
107	t = length / wsize;
108	TLOOP(src -= wsize; dst -= wsize; (word )dst = (word )src);
109	t = length & wmask;
110	TLOOP(--dst = --src);
111	}
112	done:
113	return (dst0);
114	}
115
116	__private_extern__ void *
117	memmove(void s1, const void s2, size_t n)
118	{
119	return memcpy(s1, s2, n);
120	}
121
122	__private_extern__ void
123	bcopy(const void s1, void s2, size_t n)
124	{
125	memcpy(s2, s1, n);
126	}
127
128	/*
129	* Compare memory regions.
130	*/
131	__private_extern__ int
132	memcmp(const void s1, const void s2, size_t n)
133	{
134	if (n != 0) {
135	const unsigned char p1 = s1, p2 = s2;
136
137	do {
138	if (p1++ != p2++)
139	return (--p1 - --p2);
140	} while (--n != 0);
141	}
142	return (0);
143	}