openvswitch/lib/unaligned.h

/*
 * Copyright (c) 2010, 2011 Nicira Networks.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef UNALIGNED_H
#define UNALIGNED_H 1

#include <stdint.h>
#include "byte-order.h"
#include "openvswitch/types.h"

/* Public API. */
static inline uint16_t get_unaligned_u16(const uint16_t *);
static inline uint32_t get_unaligned_u32(const uint32_t *);
static inline uint64_t get_unaligned_u64(const uint64_t *);
static inline void put_unaligned_u16(uint16_t *, uint16_t);
static inline void put_unaligned_u32(uint32_t *, uint32_t);
static inline void put_unaligned_u64(uint64_t *, uint64_t);

static inline ovs_be16 get_unaligned_be16(const ovs_be16 *);
static inline ovs_be32 get_unaligned_be32(const ovs_be32 *);
static inline ovs_be64 get_unaligned_be64(const ovs_be64 *);
static inline void put_unaligned_be16(ovs_be16 *, ovs_be16);
static inline void put_unaligned_be32(ovs_be32 *, ovs_be32);
static inline void put_unaligned_be64(ovs_be64 *, ovs_be64);

#ifdef __GNUC__
/* GCC implementations. */
#define GCC_UNALIGNED_ACCESSORS(TYPE, ABBREV)   \
struct unaligned_##ABBREV {                     \
    TYPE x __attribute__((__packed__));         \
};                                              \
static inline struct unaligned_##ABBREV *       \
unaligned_##ABBREV(const TYPE *p)               \
{                                               \
    return (struct unaligned_##ABBREV *) p;     \
}                                               \
                                                \
static inline TYPE                              \
get_unaligned_##ABBREV(const TYPE *p)           \
{                                               \
    return unaligned_##ABBREV(p)->x;            \
}                                               \
                                                \
static inline void                              \
put_unaligned_##ABBREV(TYPE *p, TYPE x)         \
{                                               \
    unaligned_##ABBREV(p)->x = x;               \
}

GCC_UNALIGNED_ACCESSORS(uint16_t, u16);
GCC_UNALIGNED_ACCESSORS(uint32_t, u32);
GCC_UNALIGNED_ACCESSORS(uint64_t, u64);

GCC_UNALIGNED_ACCESSORS(ovs_be16, be16);
GCC_UNALIGNED_ACCESSORS(ovs_be32, be32);
GCC_UNALIGNED_ACCESSORS(ovs_be64, be64);
#else
/* Generic implementations. */

static inline uint16_t get_unaligned_u16(const uint16_t *p_)
{
    const uint8_t *p = (const uint8_t *) p_;
    return ntohs((p[0] << 8) | p[1]);
}

static inline void put_unaligned_u16(uint16_t *p_, uint16_t x_)
{
    uint8_t *p = (uint8_t *) p_;
    uint16_t x = ntohs(x_);

    p[0] = x >> 8;
    p[1] = x;
}

static inline uint32_t get_unaligned_u32(const uint32_t *p_)
{
    const uint8_t *p = (const uint8_t *) p_;
    return ntohl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
}

static inline void put_unaligned_u32(uint32_t *p_, uint32_t x_)
{
    uint8_t *p = (uint8_t *) p_;
    uint32_t x = ntohl(x_);

    p[0] = x >> 24;
    p[1] = x >> 16;
    p[2] = x >> 8;
    p[3] = x;
}

static inline uint64_t get_unaligned_u64(const uint64_t *p_)
{
    const uint8_t *p = (const uint8_t *) p_;
    return ntohll(((uint64_t) p[0] << 56)
                  | ((uint64_t) p[1] << 48)
                  | ((uint64_t) p[2] << 40)
                  | ((uint64_t) p[3] << 32)
                  | (p[4] << 24)
                  | (p[5] << 16)
                  | (p[6] << 8)
                  | p[7]);
}

static inline void put_unaligned_u64(uint64_t *p_, uint64_t x_)
{
    uint8_t *p = (uint8_t *) p_;
    uint64_t x = ntohll(x_);

    p[0] = x >> 56;
    p[1] = x >> 48;
    p[2] = x >> 40;
    p[3] = x >> 32;
    p[4] = x >> 24;
    p[5] = x >> 16;
    p[6] = x >> 8;
    p[7] = x;
}

/* Only sparse cares about the difference between uint<N>_t and ovs_be<N>, and
 * that takes the GCC branch, so there's no point in working too hard on these
 * accessors. */
#define get_unaligned_be16 get_unaligned_u16
#define get_unaligned_be32 get_unaligned_u32
#define get_unaligned_be64 get_unaligned_u64
#define put_unaligned_be16 put_unaligned_u16
#define put_unaligned_be32 put_unaligned_u32
#define put_unaligned_be64 put_unaligned_u64
#endif

/* Returns the value in 'x'. */
static inline uint64_t
get_32aligned_u64(const ovs_32aligned_u64 *x)
{
	return ((uint64_t) x->hi << 32) | x->lo;
}

/* Stores 'value' in 'x'. */
static inline void
put_32aligned_u64(ovs_32aligned_u64 *x, uint64_t value)
{
	x->hi = value >> 32;
	x->lo = value;
}

/* Returns the value of 'x'. */
static inline ovs_be64
get_32aligned_be64(const ovs_32aligned_be64 *x)
{
#ifdef WORDS_BIGENDIAN
	return ((ovs_be64) x->hi << 32) | x->lo;
#else
	return ((ovs_be64) x->lo << 32) | x->hi;
#endif
}

/* Stores network byte order 'value' into 'x'. */
static inline void
put_32aligned_be64(ovs_32aligned_be64 *x, ovs_be64 value)
{
#if WORDS_BIGENDIAN
	x->hi = value >> 32;
	x->lo = value;
#else
    x->hi = value;
    x->lo = value >> 32;
#endif
}

#endif /* unaligned.h */