/*	$OpenBSD$ */

/*
 * Copyright (c) 2019 David Gwynne <dlg@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * toeplitz key byte cache
 */

struct toeplitz_bcache {
	uint32_t	bytes[256];
};

void		toeplitz_bcache_init(struct toeplitz_bcache *, uint8_t);

static inline uint32_t
toeplitz_bcache_byte(const struct toeplitz_bcache *bcache, uint8_t byte)
{
	return (bcache->bytes[byte]);
}

/*
 * symmetric toeplitz
 */

typedef uint16_t stoeplitz_key;

struct stoeplitz_cache {
	struct toeplitz_bcache bcache[sizeof(stoeplitz_key)];
};

#define STOEPLITZ_KEYSEED	0x6d5a
#define stoeplitz_htokey(_h)	htons(_h)

void		stoeplitz_cache_init(struct stoeplitz_cache *, stoeplitz_key);
void		stoeplitz_tokey(uint8_t *, size_t, stoeplitz_key)
		    __bounded((__buffer__, 1, 2));

uint32_t	stoeplitz_cache_ip4(const struct stoeplitz_cache *,
		    in_addr_t, in_addr_t);
uint32_t	stoeplitz_cache_ip4port(const struct stoeplitz_cache *,
		    in_addr_t, in_addr_t, in_port_t, in_port_t);

/* hash a uint16_t in network byte order */
static inline uint32_t
stoeplitz_cache_16(const struct stoeplitz_cache *scache, uint16_t u16)
{
	uint32_t h;

	h  = toeplitz_bcache_byte(&scache->bcache[0], u16 >> 8);
	h ^= toeplitz_bcache_byte(&scache->bcache[1], u16);

	return (h);
}

/* hash a uint16_t in host byte order */
static inline uint32_t
stoeplitz_cache_h16(const struct stoeplitz_cache *scache, uint16_t u16)
{
	uint32_t h;

#if _BYTE_ORDER == _BIG_ENDIAN
	h  = toeplitz_bcache_byte(&scache->bcache[0], u16 >> 8);
	h ^= toeplitz_bcache_byte(&scache->bcache[1], u16);
#else
	h  = toeplitz_bcache_byte(&scache->bcache[0], u16);
	h ^= toeplitz_bcache_byte(&scache->bcache[1], u16 >> 8);
#endif

	return (h);
}

/*
 * system provided symmetric toeplitz
 */

extern const struct stoeplitz_cache *const stoeplitz_syskey;

void		stoeplitz_init(void);

#define stoeplitz_h16(_h16) stoeplitz_cache_h16(stoeplitz_syskey, (_h16))