xref: /DragonStub/apps/lib/string.c (revision 823f04931913f01ee1fc0dc0c7876156ad150388)

#include <dragonstub/dragonstub.h>

char *skip_spaces(const char *str)
{
	while (isspace(*str))
		++str;
	return (char *)str;
}

unsigned int atou(const char *s)
{
	unsigned int i = 0;
	while (isdigit(*s))
		i = i * 10 + (*s++ - '0');
	return i;
}

/* Works only for digits and letters, but small and fast */
#define TOLOWER(x) ((x) | 0x20)

static unsigned int simple_guess_base(const char *cp)
{
	if (cp[0] == '0') {
		if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2]))
			return 16;
		else
			return 8;
	} else {
		return 10;
	}
}

/**
 * strlen - Find the length of a string
 * @s: The string to be sized
 */
size_t strlen(const char *s)
{
	const char *sc;

	for (sc = s; *sc != '\0'; ++sc)
		/* nothing */;
	return sc - s;
}

/**
 * simple_strtoull - convert a string to an unsigned long long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 */
unsigned long long simple_strtoull(const char *cp, char **endp,
				   unsigned int base)
{
	unsigned long long result = 0;

	if (!base)
		base = simple_guess_base(cp);

	if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x')
		cp += 2;

	while (isxdigit(*cp)) {
		unsigned int value;

		value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10;
		if (value >= base)
			break;
		result = result * base + value;
		cp++;
	}
	if (endp)
		*endp = (char *)cp;

	return result;
}

long simple_strtol(const char *cp, char **endp, unsigned int base)
{
	if (*cp == '-')
		return -simple_strtoull(cp + 1, endp, base);

	return simple_strtoull(cp, endp, base);
}

int strcmp(const char *str1, const char *str2)
{
	const unsigned char *s1 = (const unsigned char *)str1;
	const unsigned char *s2 = (const unsigned char *)str2;
	int delta = 0;

	while (*s1 || *s2) {
		delta = *s1 - *s2;
		if (delta)
			return delta;
		s1++;
		s2++;
	}
	return 0;
}

int strncmp(const char *cs, const char *ct, size_t count)
{
	unsigned char c1, c2;

	while (count) {
		c1 = *cs++;
		c2 = *ct++;
		if (c1 != c2)
			return c1 < c2 ? -1 : 1;
		if (!c1)
			break;
		count--;
	}
	return 0;
}

size_t strnlen(const char *s, size_t maxlen)
{
	const char *es = s;
	while (*es && maxlen) {
		es++;
		maxlen--;
	}

	return (es - s);
}

#define __ALIGN (sizeof(size_t))
#define ONES ((size_t)-1 / UCHAR_MAX)
#define HIGHS (ONES * (UCHAR_MAX / 2 + 1))
#define HASZERO(x) ((x)-ONES & ~(x)&HIGHS)

char *__strchrnul(const char *s, int c)
{
	c = (unsigned char)c;
	if (!c)
		return (char *)s + strlen(s);

#ifdef __GNUC__
	typedef size_t __attribute__((__may_alias__)) word;
	const word *w;
	for (; (uintptr_t)s % __ALIGN; s++)
		if (!*s || *(unsigned char *)s == c)
			return (char *)s;
	size_t k = ONES * c;
	for (w = (void *)s; !HASZERO(*w) && !HASZERO(*w ^ k); w++)
		;
	s = (void *)w;
#endif
	for (; *s && *(unsigned char *)s != c; s++)
		;
	return (char *)s;
}

char *strrchr(const char *s, int c)
{
	return memrchr(s, c, strlen(s) + 1);
}

char *strchr(const char *s, int c)
{
	char *r = __strchrnul(s, c);
	return *(unsigned char *)r == (unsigned char)c ? r : 0;
}

/**
 * strstr - Find the first substring in a %NUL terminated string
 * @s1: The string to be searched
 * @s2: The string to search for
 */
char *strstr(const char *s1, const char *s2)
{
	size_t l1, l2;

	l2 = strlen(s2);
	if (!l2)
		return (char *)s1;
	l1 = strlen(s1);
	while (l1 >= l2) {
		l1--;
		if (!memcmp(s1, s2, l2))
			return (char *)s1;
		s1++;
	}
	return NULL;
}