ardix/lib/string.c
Felix Kopp 056c318e86
Make memcmp more compiler friendly
The Thumb ISA allows incrementing a pointer right after dereferencing
it.  This commit attempts to make it more obvious to the compiler to use
this instruction in memcmp().
2020-11-19 16:33:40 +01:00

142 lines
3.5 KiB
C

/* SPDX-License-Identifier: BSD-3-Clause */
/* See the end of this file for copyright, licensing, and warranty information. */
#include <ardix/string.h>
#include <ardix/types.h>
#ifndef __HAVE_ASM_MEMCMP
int memcmp(const void *s1, const void *s2, size_t n)
{
int delta = 0;
while (n-- > 0) {
delta = *(const unsigned char *)s1++ - *(const unsigned char *)s2++;
if (delta != 0)
break;
}
return delta;
}
#endif /* __HAVE_ASM_MEMCMP */
#ifndef __HAVE_ASM_MEMCPY
void *memcpy(void *dest, const void *src, size_t n)
{
uint8_t *tmp = (uint8_t *)dest;
while (n-- > 0)
*tmp++ = *(const uint8_t *)src++;
return dest;
}
#endif /* __HAVE_ASM_MEMCPY */
#ifndef __HAVE_ASM_MEMSET
void *memset(void *ptr, int c, size_t n)
{
char *tmp = (char *)ptr;
while (n-- > 0)
*tmp++ = (char)c;
return ptr;
}
#endif /* __HAVE_ASM_MEMSET */
#ifndef __HAVE_ASM_MEMMOVE
void *memmove(void *dest, const void *src, size_t n)
{
char *tmp = (char *)dest;
const char *s = (const char *)src;
if (dest == src)
return dest;
if (dest < src) {
while (n-- != 0)
*tmp++ = *s++;
} else {
tmp += n;
s += n;
while (n-- != 0)
*--tmp = *--s;
}
return dest;
}
#endif /* __HAVE_ASM_MEMMOVE */
#ifndef __HAVE_ASM_STRCMP
int strcmp(const char *s1, const char *s2)
{
while (*s1++ == *s2++) {
if (*s1 == '\0' || *s2 == '\0')
break;
}
return *((const unsigned char *)s1) - *((const unsigned char *)s2);
}
#endif /* __HAVE_ASM_STRCMP */
#ifndef __HAVE_ASM_STRCPY
char *strcpy(char *dest, const char *src)
{
char *tmp = dest;
while ((*tmp++ = *src++) != '\0');
/* nothing */
return dest;
}
#endif /* __HAVE_ASM_STRCPY */
#ifndef __HAVE_ASM_STRNCPY
char *strncpy(char *dest, const char *src, size_t n)
{
char *tmp = dest;
while (n-- != 0) {
if ((*tmp++ = *src++) == '\0')
break;
}
return dest;
}
#endif /* __HAVE_ASM_STRNCPY */
#ifndef __HAVE_ASM_STRLEN
size_t strlen(const char *s)
{
const char *tmp = s;
while (*tmp++ != '\0');
/* nothing */
return (size_t)tmp - (size_t)s - (size_t)1;
}
#endif /* __HAVE_ASM_STRLEN */
/*
* Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>
*
* 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.
* 3. Neither the name of the copyright holder 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 COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
*/