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/* DES utility functions and macros */

#ifndef DES_UTILS_H
#define DES_UTILS_H

#include <stdint.h>
#include "intel-ipsec-mb.h"

/**
 * @brief Gets selected bit value out of a 64-bit word
 *
 * @param val 64-bit word
 * @param n bit number (0 to 63) to get value of
 *
 * @return n-th bit value (0 or 1 value only)
 */
__forceinline
uint64_t bit_get64b(const uint64_t val, const unsigned n)
{
        IMB_ASSERT(n < 64);
        return (val >> n) & UINT64_C(1);
}

/**
 * @brief Sets selected bit in a 64-bit word
 *
 * @param val 64-bit word
 * @param n bit number (0 to 63) to get value of
 * @param b bit value (0 or 1)
 *
 * @return val with n-th bit set to value b
 */
__forceinline
uint64_t bit_set64b(const uint64_t val, const unsigned n, const uint64_t b)
{
        const uint64_t m = UINT64_C(1) << n;

        IMB_ASSERT(n < 64);
        return (val & (~m)) | (b << n);
}

/**
 * @brief Permutes bits in a 64-bit word as described by pattern
 *
 * The function goes through pattern array from index 0 to 'size' (max 63).
 * It sets output bit number 'index' to value of
 * bit number 'pattern[index] - 1' from 'in'.
 *
 * @param in 64-bit word to be permuted
 * @param pattern pointer to array defining the permutation
 * @param size is size of the permutation pattern
 *
 * @return permuted in word as described by the pattern
 */
__forceinline
uint64_t permute_64b(const uint64_t in, const uint8_t *pattern, const int size)
{
        uint64_t out = 0;
        int n = 0;

        IMB_ASSERT(size <= 64);

        for (n = 0; n < size; n++) {
                /* '-1' is required as bit numbers in FIPS start with 1 not 0 */
                const int m = ((int) pattern[n]) - 1;
                const uint64_t bit_val = bit_get64b(in, m);

                out = bit_set64b(out, n, bit_val);
        }

        return out;
}

static const uint8_t reflect_tab[16] = {
        /* [ 0] 0000 => 0000 */ 0, /* [ 1] 0001 => 1000 */ 8,
        /* [ 2] 0010 => 0100 */ 4, /* [ 3] 0011 => 1100 */ 12,
        /* [ 4] 0100 => 0010 */ 2, /* [ 5] 0101 => 1010 */ 10,
        /* [ 6] 0110 => 0110 */ 6, /* [ 7] 0111 => 1110 */ 14,
        /* [ 8] 1000 => 0001 */ 1, /* [ 9] 1001 => 1001 */ 9,
        /* [10] 1010 => 0101 */ 5, /* [11] 1011 => 1101 */ 13,
        /* [12] 1100 => 0011 */ 3, /* [13] 1101 => 1011 */ 11,
        /* [14] 1110 => 0111 */ 7, /* [15] 1111 => 1111 */ 15
};

__forceinline
uint8_t reflect_8b(const uint8_t pb)
{
        return reflect_tab[pb >> 4] | (reflect_tab[pb & 15] << 4);
}

__forceinline
uint64_t load64_reflect(const void *key)
{
        const uint8_t *kb = (const uint8_t *) key;

        return ((uint64_t) reflect_8b(kb[0])) |
                ((uint64_t) reflect_8b(kb[1])) << 8 |
                ((uint64_t) reflect_8b(kb[2])) << 16 |
                ((uint64_t) reflect_8b(kb[3])) << 24 |
                ((uint64_t) reflect_8b(kb[4])) << 32 |
                ((uint64_t) reflect_8b(kb[5])) << 40 |
                ((uint64_t) reflect_8b(kb[6])) << 48 |
                ((uint64_t) reflect_8b(kb[7])) << 56;
}


#endif /* DES_UTILS_H */