// SPDX-License-Identifier: GPL-2.0

#include <crypto/internal/hash.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/xxhash.h>
#include <linux/unaligned.h>

#define XXHASH64_BLOCK_SIZE     32
#define XXHASH64_DIGEST_SIZE    8

struct xxhash64_tfm_ctx {
        u64 seed;
};

struct xxhash64_desc_ctx {
        struct xxh64_state xxhstate;
};

static int xxhash64_setkey(struct crypto_shash *tfm, const u8 *key,
                         unsigned int keylen)
{
        struct xxhash64_tfm_ctx *tctx = crypto_shash_ctx(tfm);

        if (keylen != sizeof(tctx->seed))
                return -EINVAL;
        tctx->seed = get_unaligned_le64(key);
        return 0;
}

static int xxhash64_init(struct shash_desc *desc)
{
        struct xxhash64_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
        struct xxhash64_desc_ctx *dctx = shash_desc_ctx(desc);

        xxh64_reset(&dctx->xxhstate, tctx->seed);

        return 0;
}

static int xxhash64_update(struct shash_desc *desc, const u8 *data,
                         unsigned int length)
{
        struct xxhash64_desc_ctx *dctx = shash_desc_ctx(desc);

        xxh64_update(&dctx->xxhstate, data, length);

        return 0;
}

static int xxhash64_final(struct shash_desc *desc, u8 *out)
{
        struct xxhash64_desc_ctx *dctx = shash_desc_ctx(desc);

        put_unaligned_le64(xxh64_digest(&dctx->xxhstate), out);

        return 0;
}

static int xxhash64_digest(struct shash_desc *desc, const u8 *data,
                         unsigned int length, u8 *out)
{
        struct xxhash64_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);

        put_unaligned_le64(xxh64(data, length, tctx->seed), out);

        return 0;
}

static struct shash_alg alg = {
        .digestsize     = XXHASH64_DIGEST_SIZE,
        .setkey         = xxhash64_setkey,
        .init           = xxhash64_init,
        .update         = xxhash64_update,
        .final          = xxhash64_final,
        .digest         = xxhash64_digest,
        .descsize       = sizeof(struct xxhash64_desc_ctx),
        .base           = {
                .cra_name        = "xxhash64",
                .cra_driver_name = "xxhash64-generic",
                .cra_priority    = 100,
                .cra_flags       = CRYPTO_ALG_OPTIONAL_KEY,
                .cra_blocksize   = XXHASH64_BLOCK_SIZE,
                .cra_ctxsize     = sizeof(struct xxhash64_tfm_ctx),
                .cra_module      = THIS_MODULE,
        }
};

static int __init xxhash_mod_init(void)
{
        return crypto_register_shash(&alg);
}

static void __exit xxhash_mod_fini(void)
{
        crypto_unregister_shash(&alg);
}

module_init(xxhash_mod_init);
module_exit(xxhash_mod_fini);

MODULE_AUTHOR("Nikolay Borisov <nborisov@suse.com>");
MODULE_DESCRIPTION("xxhash calculations wrapper for lib/xxhash.c");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CRYPTO("xxhash64");
MODULE_ALIAS_CRYPTO("xxhash64-generic");