eduOS/arch/x86/include/asm/string.h

147 lines
3.3 KiB
C

/*
* Written by the Chair for Operating Systems, RWTH Aachen University
*
* NO Copyright (C) 2010-2011, Stefan Lankes
* consider these trivial functions to be public domain.
*
* These functions are distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*/
/**
* @author Stefan Lankes
* @file arch/x86/include/asm/string.h
* @brief Functions related to memcpy and strings.
*
* This file deals with memcpy, memset, string functions and everything related to
* continuous byte fields.
*/
#ifndef __ARCH_STRING_H__
#define __ARCH_STRING_H__
#include <eduos/stddef.h>
#ifdef __cplusplus
extern "C" {
#endif
#ifdef HAVE_ARCH_MEMCPY
/** @brief Copy a byte range from source to dest
*
* @param dest Destination address
* @param src Source address
* @param count Range of the byte field in bytes
*/
inline static void *memcpy(void* dest, const void *src, size_t count)
{
size_t i, j, k;
if (BUILTIN_EXPECT(!dest || !src, 0))
return dest;
#ifdef CONFIG_X86_32
asm volatile (
"cld; rep movsl\n\t"
"movl %4, %%ecx\n\t"
"andl $3, %%ecx\n\t"
"rep movsb\n\t"
: "=&c"(i), "=&D"(j), "=&S"(k)
: "0"(count/4), "g"(count), "1"(dest), "2"(src) : "memory","cc");
#elif defined(CONFIG_X86_64)
asm volatile (
"cld; rep movsq\n\t"
"movq %4, %%rcx\n\t"
"andq $7, %%rcx\n\t"
"rep movsb\n\t"
: "=&c"(i), "=&D"(j), "=&S"(k)
: "0"(count/8), "g"(count), "1"(dest), "2"(src) : "memory","cc");
#endif
return dest;
}
#endif
#ifdef HAVE_ARCH_MEMSET
/** @brief Repeated write of a value to a whole range of bytes
*
* @param dest Destination address
* @param val Value to flood the range with
* @param count Size of target range in bytes
*/
inline static void *memset(void* dest, int val, size_t count)
{
size_t i, j;
if (BUILTIN_EXPECT(!dest, 0))
return dest;
asm volatile ("cld; rep stosb"
: "=&c"(i), "=&D"(j)
: "a"(val), "1"(dest), "0"(count) : "memory","cc");
return dest;
}
#endif
#ifdef HAVE_ARCH_STRLEN
/** @brief Standard string length
*
* This function computed the length of the given null terminated string
* just like the strlen functions you are used to.
*
* @return
* - The length of the string
* - 0 if str is a NULL pointer
*/
inline static size_t strlen(const char* str)
{
size_t len = 0;
size_t i, j;
if (BUILTIN_EXPECT(!str, 0))
return len;
#ifdef CONFIG_X86_32
asm volatile("not %%ecx; cld; repne scasb; not %%ecx; dec %%ecx"
: "=&c"(len), "=&D"(i), "=&a"(j)
: "2"(0), "1"(str), "0"(len)
: "memory","cc");
#elif defined(CONFIG_X86_64)
asm volatile("not %%rcx; cld; repne scasb; not %%rcx; dec %%rcx"
: "=&c"(len), "=&D"(i), "=&a"(j)
: "2"(0), "1"(str), "0"(len)
: "memory","cc");
#endif
return len;
}
#endif
#ifdef HAVE_ARCH_STRNCPY
/** @brief Copy string with maximum of n byte length
*
* @param dest Destination string pointer
* @param src Source string pointer
* @param n maximum number of bytes to copy
*/
char* strncpy(char* dest, const char* src, size_t n);
#endif
#ifdef HAVE_ARCH_STRCPY
/** @brief Copy string
*
* Note that there is another safer variant of this function: strncpy.\n
* That one could save you from accidents with buffer overruns.
*
* @param dest Destination string pointer
* @param src Source string pointer
*/
char* strcpy(char* dest, const char* src);
#endif
#ifdef __cplusplus
}
#endif
#endif