/*
 * Copyright 1995-2024 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#define idea_mul(r, a, b, ul)                                          \
    ul = (unsigned long)a * b;                                         \
    if (ul != 0) {                                                     \
        r = (ul & 0xffff) - (ul >> 16);                                \
        r -= ((r) >> 16);                                              \
    } else {                                                           \
        r = (-(int)a - b + 1); /* assuming a or b is 0 and in range */ \
    }

/* NOTE - c is not incremented as per n2l */
#define n2ln(c, l1, l2, n)                           \
    {                                                \
        c += n;                                      \
        l1 = l2 = 0;                                 \
        switch (n) {                                 \
        case 8:                                      \
            l2 = ((unsigned long)(*(--(c))));        \
        /* fall through */                           \
        case 7:                                      \
            l2 |= ((unsigned long)(*(--(c)))) << 8;  \
        /* fall through */                           \
        case 6:                                      \
            l2 |= ((unsigned long)(*(--(c)))) << 16; \
        /* fall through */                           \
        case 5:                                      \
            l2 |= ((unsigned long)(*(--(c)))) << 24; \
        /* fall through */                           \
        case 4:                                      \
            l1 = ((unsigned long)(*(--(c))));        \
        /* fall through */                           \
        case 3:                                      \
            l1 |= ((unsigned long)(*(--(c)))) << 8;  \
        /* fall through */                           \
        case 2:                                      \
            l1 |= ((unsigned long)(*(--(c)))) << 16; \
        /* fall through */                           \
        case 1:                                      \
            l1 |= ((unsigned long)(*(--(c)))) << 24; \
        }                                            \
    }

/* NOTE - c is not incremented as per l2n */
#define l2nn(l1, l2, c, n)                                   \
    {                                                        \
        c += n;                                              \
        switch (n) {                                         \
        case 8:                                              \
            *(--(c)) = (unsigned char)(((l2)) & 0xff);       \
        /* fall through */                                   \
        case 7:                                              \
            *(--(c)) = (unsigned char)(((l2) >> 8) & 0xff);  \
        /* fall through */                                   \
        case 6:                                              \
            *(--(c)) = (unsigned char)(((l2) >> 16) & 0xff); \
        /* fall through */                                   \
        case 5:                                              \
            *(--(c)) = (unsigned char)(((l2) >> 24) & 0xff); \
        /* fall through */                                   \
        case 4:                                              \
            *(--(c)) = (unsigned char)(((l1)) & 0xff);       \
        /* fall through */                                   \
        case 3:                                              \
            *(--(c)) = (unsigned char)(((l1) >> 8) & 0xff);  \
        /* fall through */                                   \
        case 2:                                              \
            *(--(c)) = (unsigned char)(((l1) >> 16) & 0xff); \
        /* fall through */                                   \
        case 1:                                              \
            *(--(c)) = (unsigned char)(((l1) >> 24) & 0xff); \
        }                                                    \
    }

#undef n2l
#define n2l(c, l) (l = ((unsigned long)(*((c)++))) << 24L, \
    l |= ((unsigned long)(*((c)++))) << 16L,               \
    l |= ((unsigned long)(*((c)++))) << 8L,                \
    l |= ((unsigned long)(*((c)++))))

#undef l2n
#define l2n(l, c) (*((c)++) = (unsigned char)(((l) >> 24L) & 0xff), \
    *((c)++) = (unsigned char)(((l) >> 16L) & 0xff),                \
    *((c)++) = (unsigned char)(((l) >> 8L) & 0xff),                 \
    *((c)++) = (unsigned char)(((l)) & 0xff))

#undef s2n
#define s2n(l, c) (*((c)++) = (unsigned char)(((l)) & 0xff), \
    *((c)++) = (unsigned char)(((l) >> 8L) & 0xff))

#undef n2s
#define n2s(c, l) (l = ((IDEA_INT)(*((c)++))) << 8L, \
    l |= ((IDEA_INT)(*((c)++))))

#define E_IDEA(num)                       \
    x1 &= 0xffff;                         \
    idea_mul(x1, x1, *p, ul);             \
    p++;                                  \
    x2 += *(p++);                         \
    x3 += *(p++);                         \
    x4 &= 0xffff;                         \
    idea_mul(x4, x4, *p, ul);             \
    p++;                                  \
    t0 = (x1 ^ x3) & 0xffff;              \
    idea_mul(t0, t0, *p, ul);             \
    p++;                                  \
    t1 = (t0 + (x2 ^ x4)) & 0xffff;       \
    idea_mul(t1, t1, *p, ul);             \
    p++;                                  \
    t0 += t1;                             \
    x1 ^= t1;                             \
    x4 ^= t0;                             \
    ul = x2 ^ t0; /* do the swap to x3 */ \
    x2 = x3 ^ t1;                         \
    x3 = ul;