mirror of
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165 lines
3.7 KiB
C++
165 lines
3.7 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/StdLib.h>
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extern "C" {
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void* memcpy(void* dest_ptr, void const* src_ptr, size_t n)
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{
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#if ARCH(I386) || ARCH(X86_64)
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size_t dest = (size_t)dest_ptr;
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size_t src = (size_t)src_ptr;
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// FIXME: Support starting at an unaligned address.
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if (!(dest & 0x3) && !(src & 0x3) && n >= 12) {
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size_t size_ts = n / sizeof(size_t);
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# if ARCH(I386)
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asm volatile(
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"rep movsl\n"
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: "=S"(src), "=D"(dest)
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: "S"(src), "D"(dest), "c"(size_ts)
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: "memory");
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# else
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asm volatile(
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"rep movsq\n"
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: "=S"(src), "=D"(dest)
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: "S"(src), "D"(dest), "c"(size_ts)
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: "memory");
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# endif
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n -= size_ts * sizeof(size_t);
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if (n == 0)
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return dest_ptr;
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}
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asm volatile(
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"rep movsb\n" ::"S"(src), "D"(dest), "c"(n)
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: "memory");
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#else
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u8* pd = (u8*)dest_ptr;
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u8 const* ps = (u8 const*)src_ptr;
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for (; n--;)
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*pd++ = *ps++;
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#endif
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return dest_ptr;
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}
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void* memmove(void* dest, void const* src, size_t n)
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{
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if (dest < src)
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return memcpy(dest, src, n);
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u8* pd = (u8*)dest;
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u8 const* ps = (u8 const*)src;
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for (pd += n, ps += n; n--;)
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*--pd = *--ps;
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return dest;
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}
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void* memset(void* dest_ptr, int c, size_t n)
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{
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#if ARCH(I386) || ARCH(X86_64)
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size_t dest = (size_t)dest_ptr;
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// FIXME: Support starting at an unaligned address.
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if (!(dest & 0x3) && n >= 12) {
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size_t size_ts = n / sizeof(size_t);
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size_t expanded_c = explode_byte((u8)c);
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# if ARCH(I386)
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asm volatile(
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"rep stosl\n"
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: "=D"(dest)
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: "D"(dest), "c"(size_ts), "a"(expanded_c)
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: "memory");
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# else
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asm volatile(
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"rep stosq\n"
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: "=D"(dest)
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: "D"(dest), "c"(size_ts), "a"(expanded_c)
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: "memory");
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# endif
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n -= size_ts * sizeof(size_t);
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if (n == 0)
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return dest_ptr;
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}
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asm volatile(
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"rep stosb\n"
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: "=D"(dest), "=c"(n)
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: "0"(dest), "1"(n), "a"(c)
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: "memory");
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#else
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u8* pd = (u8*)dest_ptr;
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for (; n--;)
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*pd++ = c;
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#endif
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return dest_ptr;
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}
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size_t strlen(char const* str)
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{
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size_t len = 0;
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while (*(str++))
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++len;
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return len;
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}
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size_t strnlen(char const* str, size_t maxlen)
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{
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size_t len = 0;
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for (; len < maxlen && *str; str++)
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len++;
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return len;
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}
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int strcmp(char const* s1, char const* s2)
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{
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for (; *s1 == *s2; ++s1, ++s2) {
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if (*s1 == 0)
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return 0;
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}
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return *(u8 const*)s1 < *(u8 const*)s2 ? -1 : 1;
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}
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int memcmp(void const* v1, void const* v2, size_t n)
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{
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auto const* s1 = (u8 const*)v1;
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auto const* s2 = (u8 const*)v2;
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while (n-- > 0) {
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if (*s1++ != *s2++)
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return s1[-1] < s2[-1] ? -1 : 1;
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}
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return 0;
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}
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int strncmp(char const* s1, char const* s2, size_t n)
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{
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if (!n)
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return 0;
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do {
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if (*s1 != *s2++)
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return *(unsigned char const*)s1 - *(unsigned char const*)--s2;
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if (*s1++ == 0)
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break;
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} while (--n);
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return 0;
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}
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char* strstr(char const* haystack, char const* needle)
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{
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char nch;
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char hch;
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if ((nch = *needle++) != 0) {
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size_t len = strlen(needle);
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do {
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do {
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if ((hch = *haystack++) == 0)
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return nullptr;
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} while (hch != nch);
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} while (strncmp(haystack, needle, len) != 0);
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--haystack;
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}
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return const_cast<char*>(haystack);
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}
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}
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