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/* ************************************************************************** */
/* */
/* ::: :::::::: */
/* ft_memmem.c :+: :+: :+: */
/* +:+ +:+ +:+ */
/* By: cacharle <marvin@42.fr> +#+ +:+ +#+ */
/* +#+#+#+#+#+ +#+ */
/* Created: 2020/02/13 01:54:55 by cacharle #+# #+# */
/* Updated: 2020/02/13 21:04:46 by cacharle ### ########.fr */
/* */
/* ************************************************************************** */
#include "libft_mem.h"
#define BAD_TABLE_SIZE 256
static void st_bad_table_init(size_t bad_table[BAD_TABLE_SIZE],
const char *little, size_t little_len)
{
size_t i;
i = 0;
while (i < BAD_TABLE_SIZE)
bad_table[i++] = little_len;
i = 0;
while (i < little_len - 1)
{
bad_table[(int)little[i]] = little_len - i - 1;
i++;
}
}
static int st_memcmp_end(const void *s1, const void *s2, size_t n)
{
while (n-- > 0)
if (*(t_ftbyte*)(s1 + n) != *(t_ftbyte*)(s2 + n))
return (*(t_ftbyte*)(s1 + n) - *(t_ftbyte*)(s2 + n));
return (0);
}
void *ft_memmem(const void *big, size_t big_len,
const void *little, size_t little_len)
{
size_t i;
size_t bad_table[BAD_TABLE_SIZE];
if (big_len < little_len || little_len == 0 || big_len == 0)
return (NULL);
st_bad_table_init(bad_table, little, little_len);
i = 0;
while (i <= big_len - little_len)
{
if (st_memcmp_end(big + i, little, little_len) == 0)
return ((void*)big + i);
i += bad_table[*(t_ftbyte*)(big + i + little_len - 1)];
}
return (NULL);
}
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