libc.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void *memset(void *m, int c, size_t n)
{
	char *s = (char *) m;

	while (n--)
		*s++ = (char) c;

	return m;
}

void *memcpy(void *dst0, const void *src0, size_t n)
{
	char *dst = (char *)dst0;
	char *src = (char *)src0;

	void *save = dst0;

	while (n--)
		*dst++ = *src++;

	return save;
}

int memcmp(const void* s1, const void* s2, size_t n)
{
	const unsigned char *p1 = s1, *p2 = s2;
	while(n--)
		if( *p1 != *p2 )
			return *p1 - *p2;
		else
			p1++, p2++;

	return 0;
}


size_t strlen(const char *s)
{
	const char *p = s;
	while (*s) s++;
	return s - p;
}


char *strchr(const char *s, int c)
{
	if(!s) return 0;

	while (*s != (char)c)
		if (!*s++)
			return 0;

	return (char *)s;
}

char *strrchr(const char *s, int c)
{
	if(!s) return 0;

	char *ret = 0;
	char cc = (char)c;

	do
	{
		if( *s == cc ) ret = (char*)s;
	}
	while(*s++);

	return ret;
}

char *strstr(const char *s1, const char *s2)
{
	if(!s1) return 0;

	size_t n = strlen(s2); if(n == 0) return 0;

	while(*s1)
		if(!memcmp(s1++, s2, n))
			return (char*)(s1 - 1);

	return 0;
}

int strncasecmp (__const char *s1, __const char *s2, size_t n)
{
	int c1, c2;

	while(n--)
	{
		c1 = *((unsigned char *)(s1++)); if (c1 >= 'A' && c1 <= 'Z') c1 += 0x20; // ('a' - 'A')
		c2 = *((unsigned char *)(s2++)); if (c2 >= 'A' && c2 <= 'Z') c2 += 0x20; // ('a' - 'A')
		if (c1 != c2)   return (c1 - c2);
		if (c1 == '\0') return 0;
	}

	return 0;
}

int strcasecmp (__const char *s1, __const char *s2)
{
	int c1, c2;

	while(*s1)
	{
		c1 = *((unsigned char *)(s1++)); if (c1 >= 'A' && c1 <= 'Z') c1 += 0x20; // ('a' - 'A')
		c2 = *((unsigned char *)(s2++)); if (c2 >= 'A' && c2 <= 'Z') c2 += 0x20; // ('a' - 'A')
		if (c1 != c2)   return (c1 - c2);
	}

	return 0;
}

char *strcasestr(const char *s1, const char *s2);
char *strcasestr(const char *s1, const char *s2)
{
	if(!s1) return 0;

	size_t n = strlen(s2); if(n == 0) return 0;

	while(*s1)
		if(!strncasecmp(s1++, s2, n))
			return (char*)(s1 - 1);

	return 0;
}

int strncmp(const char *s1, const char *s2, size_t n)
{
	if(n == 0) return 0;

	while((n > 0) && *s1 && (*s1==*s2)) s1++, s2++, n--;

	return *(const unsigned char*)s1-*(const unsigned char*)s2;
}

int strcmp(const char *s1, const char *s2)
{
	while(*s1 && (*s1==*s2)) s1++, s2++;

	return *(const unsigned char*)s1 - *(const unsigned char*)s2;
}


char *strcpy(char *dest, const char* src)
{
	char *ret = dest;

	while ((*dest++ = *src++)) ;

	return ret;
}

char *strncpy(char *dest, const char *src, size_t n)
{
	char *ret = dest;

	do
	{
		if (!n--) return ret;
	}
	while ((*dest++ = *src++));

	while (n--) *dest++ = 0;

	return ret;
}

char *strcat(char *dest, const char *src)
{
	char *ret = dest;

	while (*dest) dest++;

	while ((*dest++ = *src++)) ;

	return ret;
}

char *strtok(char *str, const char *delim)
{
	static char* p = 0;

	if(str) p = str;
	else
	if(!p) return 0;

	str = p + strspn(p, delim);
	p = str + strcspn(str, delim);

	if(p == str) return p = 0;

	p = *p ? *p = 0, p + 1 : 0;
	return str;
}

size_t strcspn(const char *s1, const char *s2)
{
	size_t ret = 0;
	while(*s1)
		if(strchr(s2,*s1))
			return ret;
		else
			s1++, ret++;

	return ret;
}

size_t strspn(const char *s1, const char *s2)
{
	size_t ret = 0;
	while(*s1 && strchr(s2, *s1++))
		ret++;
	return ret;
}

int extcmp(const char *s1, const char *s2, size_t n);
int extcmp(const char *s1, const char *s2, size_t n)
{
	size_t s = strlen(s1);
	if(n > s) return -1;
	return memcmp(s1 + (s - n), s2, n);
}

int extcasecmp(const char *s1, const char *s2, size_t n);
int extcasecmp(const char *s1, const char *s2, size_t n)
{
	size_t s = strlen(s1);
	if(n > s) return -1;
	return strncasecmp(s1 + (s - n), s2, n);
}