/* See LICENSE file for copyright and license details. */
#include "common.h"
#ifndef TEST


void *
libsimple_memmem(const void *hay_, size_t hayn, const void *sub_, size_t subn)
{
	const unsigned char *hay = hay_;
	const unsigned char *sub = sub_;
	size_t *next, i, j;

	if (!subn)
		return REMOVE_CONST(hay, unsigned char *);
	if (hayn < subn)
		return NULL;
	if (subn == 1)
		return memchr(hay, *sub, hayn);

	next = alloca((subn + 1U) * sizeof(*next));
	i = 0, j = SIZE_MAX;
	goto beginning;
	for (; i < subn; i++, j++) {
		if (sub[i] == sub[j]) {
			next[i] = next[j];
		} else {
		beginning:
			next[i] = j;
			while (j != SIZE_MAX && sub[i] != sub[j])
				j = next[j];
		}
	}

	for (i = j = 0; i < hayn;) {
		while (j != SIZE_MAX && sub[j] != hay[i])
			j = next[j];
		i++;
		if (++j == subn) {
			hay = &hay[i - j];
			return REMOVE_CONST(hay, unsigned char *);
		}
	}

	return NULL;
}


#else
#include "test.h"

int
main(void)
{
	assert(!strcmpnul(libsimple_memmem("test", 4, "test", 4), "test"));
	assert(!strcmpnul(libsimple_memmem("", 0, "", 0), ""));
	assert(!strcmpnul(libsimple_memmem("test", 4, "", 0), "test"));
	assert(!libsimple_memmem("", 0, "test", 4));
	assert(!libsimple_memmem("t", 1, "test", 4));
	assert(!strcmpnul(libsimple_memmem("test", 4, "t", 1), "test"));
	assert(!strcmpnul(libsimple_memmem("test", 4, "e", 1), "est"));
	assert(!strcmpnul(libsimple_memmem("test", 4, "s", 1), "st"));
	assert(!libsimple_memmem("test", 4, "x", 1));
	assert(!strcmpnul(libsimple_memmem("test", 4, "te", 2), "test"));
	assert(!strcmpnul(libsimple_memmem("test", 4, "es", 2), "est"));
	assert(!strcmpnul(libsimple_memmem("test", 4, "st", 2), "st"));
	assert(!strcmpnul(libsimple_memmem("test", 5, "t", 2), "t"));
	assert(!libsimple_memmem("test", 4, "xx", 2));
	assert(!strcmpnul(libsimple_memmem("abc", 3, "c", 1), "c"));
	assert(!strcmpnul(libsimple_memmem("abc", 3, "bc", 2), "bc"));
	assert(!strcmpnul(libsimple_memmem("abc", 3, "abc", 3), "abc"));
	assert(!libsimple_memmem("abc", 3, "abc", 4));
	assert(!strcmpnul(libsimple_memmem("abcabc", 6, "bc", 2), "bcabc"));
	assert(!strcmpnul(libsimple_memmem("ABCABC", 6, "BC", 2), "BCABC"));
	assert(!libsimple_memmem("ABCDEF", 6, "bc", 2));
	assert(!libsimple_memmem("abcdef", 6, "BC", 2));
	return 0;
}

#endif