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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/StdLib.h>
extern "C" {
void* memcpy(void* dest_ptr, void const* src_ptr, size_t n)
{
#if ARCH(X86_64)
size_t dest = (size_t)dest_ptr;
size_t src = (size_t)src_ptr;
// FIXME: Support starting at an unaligned address.
if (!(dest & 0x3) && !(src & 0x3) && n >= 12) {
size_t size_ts = n / sizeof(size_t);
asm volatile(
"rep movsq\n"
: "=S"(src), "=D"(dest)
: "S"(src), "D"(dest), "c"(size_ts)
: "memory");
n -= size_ts * sizeof(size_t);
if (n == 0)
return dest_ptr;
}
asm volatile(
"rep movsb\n" ::"S"(src), "D"(dest), "c"(n)
: "memory");
#else
u8* pd = (u8*)dest_ptr;
u8 const* ps = (u8 const*)src_ptr;
for (; n--;)
*pd++ = *ps++;
#endif
return dest_ptr;
}
void* memmove(void* dest, void const* src, size_t n)
{
if (dest < src)
return memcpy(dest, src, n);
u8* pd = (u8*)dest;
u8 const* ps = (u8 const*)src;
for (pd += n, ps += n; n--;)
*--pd = *--ps;
return dest;
}
void* memset(void* dest_ptr, int c, size_t n)
{
#if ARCH(X86_64)
size_t dest = (size_t)dest_ptr;
// FIXME: Support starting at an unaligned address.
if (!(dest & 0x3) && n >= 12) {
size_t size_ts = n / sizeof(size_t);
size_t expanded_c = explode_byte((u8)c);
asm volatile(
"rep stosq\n"
: "=D"(dest)
: "D"(dest), "c"(size_ts), "a"(expanded_c)
: "memory");
n -= size_ts * sizeof(size_t);
if (n == 0)
return dest_ptr;
}
asm volatile(
"rep stosb\n"
: "=D"(dest), "=c"(n)
: "0"(dest), "1"(n), "a"(c)
: "memory");
#else
u8* pd = (u8*)dest_ptr;
for (; n--;)
*pd++ = c;
#endif
return dest_ptr;
}
size_t strlen(char const* str)
{
size_t len = 0;
while (*(str++))
++len;
return len;
}
size_t strnlen(char const* str, size_t maxlen)
{
size_t len = 0;
for (; len < maxlen && *str; str++)
len++;
return len;
}
int strcmp(char const* s1, char const* s2)
{
for (; *s1 == *s2; ++s1, ++s2) {
if (*s1 == 0)
return 0;
}
return *(u8 const*)s1 < *(u8 const*)s2 ? -1 : 1;
}
int memcmp(void const* v1, void const* v2, size_t n)
{
auto const* s1 = (u8 const*)v1;
auto const* s2 = (u8 const*)v2;
while (n-- > 0) {
if (*s1++ != *s2++)
return s1[-1] < s2[-1] ? -1 : 1;
}
return 0;
}
int strncmp(char const* s1, char const* s2, size_t n)
{
if (!n)
return 0;
do {
if (*s1 != *s2++)
return *(unsigned char const*)s1 - *(unsigned char const*)--s2;
if (*s1++ == 0)
break;
} while (--n);
return 0;
}
char* strstr(char const* haystack, char const* needle)
{
char nch;
char hch;
if ((nch = *needle++) != 0) {
size_t len = strlen(needle);
do {
do {
if ((hch = *haystack++) == 0)
return nullptr;
} while (hch != nch);
} while (strncmp(haystack, needle, len) != 0);
--haystack;
}
return const_cast<char*>(haystack);
}
}
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