/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_VIRTIO_FEATURES_H
#define _LINUX_VIRTIO_FEATURES_H

#include <linux/bits.h>
#include <linux/bug.h>
#include <linux/string.h>

#define VIRTIO_FEATURES_U64S    2
#define VIRTIO_FEATURES_BITS    (VIRTIO_FEATURES_U64S * 64)

#define VIRTIO_BIT(b)           BIT_ULL((b) & 0x3f)
#define VIRTIO_U64(b)           ((b) >> 6)

#define VIRTIO_DECLARE_FEATURES(name)                   \
        union {                                         \
                u64 name;                               \
                u64 name##_array[VIRTIO_FEATURES_U64S];\
        }

static inline bool virtio_features_chk_bit(unsigned int bit)
{
        if (__builtin_constant_p(bit)) {
                /*
                 * Don't care returning the correct value: the build
                 * will fail before any bad features access
                 */
                BUILD_BUG_ON(bit >= VIRTIO_FEATURES_BITS);
        } else {
                if (WARN_ON_ONCE(bit >= VIRTIO_FEATURES_BITS))
                        return false;
        }
        return true;
}

static inline bool virtio_features_test_bit(const u64 *features,
                                            unsigned int bit)
{
        return virtio_features_chk_bit(bit) &&
               !!(features[VIRTIO_U64(bit)] & VIRTIO_BIT(bit));
}

static inline void virtio_features_set_bit(u64 *features,
                                           unsigned int bit)
{
        if (virtio_features_chk_bit(bit))
                features[VIRTIO_U64(bit)] |= VIRTIO_BIT(bit);
}

static inline void virtio_features_clear_bit(u64 *features,
                                             unsigned int bit)
{
        if (virtio_features_chk_bit(bit))
                features[VIRTIO_U64(bit)] &= ~VIRTIO_BIT(bit);
}

static inline void virtio_features_zero(u64 *features)
{
        memset(features, 0, sizeof(features[0]) * VIRTIO_FEATURES_U64S);
}

static inline void virtio_features_from_u64(u64 *features, u64 from)
{
        virtio_features_zero(features);
        features[0] = from;
}

static inline bool virtio_features_equal(const u64 *f1, const u64 *f2)
{
        int i;

        for (i = 0; i < VIRTIO_FEATURES_U64S; ++i)
                if (f1[i] != f2[i])
                        return false;
        return true;
}

static inline void virtio_features_copy(u64 *to, const u64 *from)
{
        memcpy(to, from, sizeof(to[0]) * VIRTIO_FEATURES_U64S);
}

static inline void virtio_features_andnot(u64 *to, const u64 *f1, const u64 *f2)
{
        int i;

        for (i = 0; i < VIRTIO_FEATURES_U64S; i++)
                to[i] = f1[i] & ~f2[i];
}

#endif