/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * sm3_base.h - core logic for SM3 implementations
 *
 * Copyright (C) 2017 ARM Limited or its affiliates.
 * Written by Gilad Ben-Yossef <gilad@benyossef.com>
 */

#ifndef _CRYPTO_SM3_BASE_H
#define _CRYPTO_SM3_BASE_H

#include <crypto/internal/hash.h>
#include <crypto/sm3.h>
#include <linux/math.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/unaligned.h>

typedef void (sm3_block_fn)(struct sm3_state *sst, u8 const *src, int blocks);

static inline int sm3_base_init(struct shash_desc *desc)
{
        sm3_init(shash_desc_ctx(desc));
        return 0;
}

static inline int sm3_base_do_update_blocks(struct shash_desc *desc,
                                            const u8 *data, unsigned int len,
                                            sm3_block_fn *block_fn)
{
        unsigned int remain = len - round_down(len, SM3_BLOCK_SIZE);
        struct sm3_state *sctx = shash_desc_ctx(desc);

        sctx->count += len - remain;
        block_fn(sctx, data, len / SM3_BLOCK_SIZE);
        return remain;
}

static inline int sm3_base_do_finup(struct shash_desc *desc,
                                    const u8 *src, unsigned int len,
                                    sm3_block_fn *block_fn)
{
        unsigned int bit_offset = SM3_BLOCK_SIZE / 8 - 1;
        struct sm3_state *sctx = shash_desc_ctx(desc);
        union {
                __be64 b64[SM3_BLOCK_SIZE / 4];
                u8 u8[SM3_BLOCK_SIZE * 2];
        } block = {};

        if (len >= SM3_BLOCK_SIZE) {
                int remain;

                remain = sm3_base_do_update_blocks(desc, src, len, block_fn);
                src += len - remain;
                len = remain;
        }

        if (len >= bit_offset * 8)
                bit_offset += SM3_BLOCK_SIZE / 8;
        memcpy(&block, src, len);
        block.u8[len] = 0x80;
        sctx->count += len;
        block.b64[bit_offset] = cpu_to_be64(sctx->count << 3);
        block_fn(sctx, block.u8, (bit_offset + 1) * 8 / SM3_BLOCK_SIZE);
        memzero_explicit(&block, sizeof(block));

        return 0;
}

static inline int sm3_base_finish(struct shash_desc *desc, u8 *out)
{
        struct sm3_state *sctx = shash_desc_ctx(desc);
        __be32 *digest = (__be32 *)out;
        int i;

        for (i = 0; i < SM3_DIGEST_SIZE / sizeof(__be32); i++)
                put_unaligned_be32(sctx->state[i], digest++);
        return 0;
}

#endif /* _CRYPTO_SM3_BASE_H */