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/* SPDX-License-Identifier: MIT */
#include <stdbool.h>
#include "string.h"
// Routines based on The Public Domain C Library
void *memcpy(void *s1, const void *s2, size_t n)
{
char *dest = (char *)s1;
const char *src = (const char *)s2;
while (n--) {
*dest++ = *src++;
}
return s1;
}
void *memmove(void *s1, const void *s2, size_t n)
{
char *dest = (char *)s1;
const char *src = (const char *)s2;
if (dest <= src) {
while (n--) {
*dest++ = *src++;
}
} else {
src += n;
dest += n;
while (n--) {
*--dest = *--src;
}
}
return s1;
}
int memcmp(const void *s1, const void *s2, size_t n)
{
const unsigned char *p1 = (const unsigned char *)s1;
const unsigned char *p2 = (const unsigned char *)s2;
while (n--) {
if (*p1 != *p2) {
return *p1 - *p2;
}
++p1;
++p2;
}
return 0;
}
void *memset(void *s, int c, size_t n)
{
unsigned char *p = (unsigned char *)s;
while (n--) {
*p++ = (unsigned char)c;
}
return s;
}
void *memchr(const void *s, int c, size_t n)
{
const unsigned char *p = (const unsigned char *)s;
while (n--) {
if (*p == (unsigned char)c) {
return (void *)p;
}
++p;
}
return NULL;
}
char *strcpy(char *s1, const char *s2)
{
char *rc = s1;
while ((*s1++ = *s2++)) {
/* EMPTY */
}
return rc;
}
char *strncpy(char *s1, const char *s2, size_t n)
{
char *rc = s1;
while (n && (*s1++ = *s2++)) {
/* Cannot do "n--" in the conditional as size_t is unsigned and we have
to check it again for >0 in the next loop below, so we must not risk
underflow.
*/
--n;
}
/* Checking against 1 as we missed the last --n in the loop above. */
while (n-- > 1) {
*s1++ = '\0';
}
return rc;
}
int strcmp(const char *s1, const char *s2)
{
while ((*s1) && (*s1 == *s2)) {
++s1;
++s2;
}
return (*(unsigned char *)s1 - *(unsigned char *)s2);
}
int strncmp(const char *s1, const char *s2, size_t n)
{
while (n && *s1 && (*s1 == *s2)) {
++s1;
++s2;
--n;
}
if (n == 0) {
return 0;
} else {
return (*(unsigned char *)s1 - *(unsigned char *)s2);
}
}
size_t strlen(const char *s)
{
size_t rc = 0;
while (s[rc]) {
++rc;
}
return rc;
}
size_t strnlen(const char *s, size_t n)
{
size_t rc = 0;
while (rc < n && s[rc]) {
++rc;
}
return rc;
}
char *strchr(const char *s, int c)
{
do {
if (*s == (char)c) {
return (char *)s;
}
} while (*s++);
return NULL;
}
char *strrchr(const char *s, int c)
{
size_t i = 0;
while (s[i++]) {
/* EMPTY */
}
do {
if (s[--i] == (char)c) {
return (char *)s + i;
}
} while (i);
return NULL;
}
/* Very naive, no attempt to check for errors */
long atol(const char *s)
{
long val = 0;
bool neg = false;
if (*s == '-') {
neg = true;
s++;
}
while (*s >= '0' && *s <= '9')
val = (val * 10) + (*s++ - '0');
if (neg)
val = -val;
return val;
}
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