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// SPDX-License-Identifier: GPL-2.0
#ifndef STRING_H
#define STRING_H
/**
* \file
*
* Provides a subset of the functions normally provided by <string.h>.
*
*//*
* Copyright (C) 2020-2022 Martin Whitaker.
*/
#include <stddef.h>
/**
* Compares the first n bytes of the memory areas pointed to by s1 and s2
* and returns 0 if all bytes are the same or the numerical difference
* between the first mismatching byte in s1 (interpreted as an unsigned
* value) and the corresponding byte in s2.
*/
static inline int memcmp(const void *s1, const void *s2, size_t n)
{
const unsigned char *src1 = s1, *src2 = s2;
for (size_t i = 0; i < n; i++) {
if (src1[i] != src2[i]) {
return (int)src1[i] - (int)src2[i];
}
}
return 0;
}
/**
* Copies n bytes from the memory area pointed to by src to the memory area
* pointed to by dest and returns a pointer to dest. The memory areas must
* not overlap.
* void *memcpy(void *dst, const void *src, size_t n);
*/
#define memcpy(d, s, n) __builtin_memcpy((d), (s), (n))
/**
* Copies n bytes from the memory area pointed to by src to the memory area
* pointed to by dest and returns a pointer to dest. The memory areas may
* overlap.
*/
void *memmove(void *dest, const void *src, size_t n);
/**
* Fills the first n bytes of the memory area pointed to by s with the byte
* value c.
* void *memset(void *s, int c, size_t n);
*/
#define memset(s, c, n) __builtin_memset((s), (c), (n))
/**
* Returns the string length, excluding the terminating null character.
*/
static inline size_t strlen(const char *s)
{
size_t len = 0;
while (*s++) {
len++;
}
return len;
}
/**
* Compares at most the first n characters in the strings s1 and s2 and
* returns 0 if all characters are the same or the numerical difference
* between the first mismatching character in s1 (interpreted as a signed
* value) and the corresponding character in s2.
*/
static inline int strncmp(const char *s1, const char *s2, size_t n)
{
for (size_t i = 0; i < n; i++) {
if (s1[i] != s2[i]) {
return (int)s1[i] - (int)s2[i];
}
if (s1[i] == '\0') {
return 0;
}
}
return 0;
}
/**
* Finds the first occurrence of the substring needle in the string haystack
* and returns a pointer to the beginning of the located substring, or NULL
* if the substring is not found.
*/
char *strstr(const char *haystack, const char *needle);
/**
* Convert n to characters in s
*/
char *itoa(int num, char *str);
#endif // STRING_H
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