/*

   SipHash reference C implementation

   Copyright (c) 2012-2021 Jean-Philippe Aumasson

   <jeanphilippe.aumasson@gmail.com>

   Copyright (c) 2012-2014 Daniel J. Bernstein <djb@cr.yp.to>

   To the extent possible under law, the author(s) have dedicated all copyright

   and related and neighboring rights to this software to the public domain

   worldwide. This software is distributed without any warranty.

   You should have received a copy of the CC0 Public Domain Dedication along

   with

   this software. If not, see

   <http://creativecommons.org/publicdomain/zero/1.0/>.

 */

#include "passgen/util/siphash.h"

#include <assert.h>

#include <stdint.h>

#include <stdio.h>

/* default: SipHash-2-4 */

#ifndef cROUNDS

#define cROUNDS 2

#endif

#ifndef dROUNDS

#define dROUNDS 4

#endif

#define ROTL(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b))))

#define U32TO8_LE(p, v)             \

    (p)[0] = (uint8_t) ((v));       \

    (p)[1] = (uint8_t) ((v) >> 8);  \

    (p)[2] = (uint8_t) ((v) >> 16); \

    (p)[3] = (uint8_t) ((v) >> 24);

#define U64TO8_LE(p, v)               \

    U32TO8_LE((p), (uint32_t) ((v))); \

    U32TO8_LE((p) + 4, (uint32_t) ((v) >> 32));

#define U8TO64_LE(p)                                             \

    (((uint64_t) ((p)[0])) | ((uint64_t) ((p)[1]) << 8) |        \

     ((uint64_t) ((p)[2]) << 16) | ((uint64_t) ((p)[3]) << 24) | \

     ((uint64_t) ((p)[4]) << 32) | ((uint64_t) ((p)[5]) << 40) | \

     ((uint64_t) ((p)[6]) << 48) | ((uint64_t) ((p)[7]) << 56))

#define SIPROUND           \

    do {                   \

        v0 += v1;          \

        v1 = ROTL(v1, 13); \

        v1 ^= v0;          \

        v0 = ROTL(v0, 32); \

        v2 += v3;          \

        v3 = ROTL(v3, 16); \

        v3 ^= v2;          \

        v0 += v3;          \

        v3 = ROTL(v3, 21); \

        v3 ^= v0;          \

        v2 += v1;          \

        v1 = ROTL(v1, 17); \

        v1 ^= v2;          \

        v2 = ROTL(v2, 32); \

    } while(0)

#ifdef DEBUG

#define TRACE                                            \

    do {                                                 \

        printf("(%3zu) v0 %016" PRIx64 "\n", inlen, v0); \

        printf("(%3zu) v1 %016" PRIx64 "\n", inlen, v1); \

        printf("(%3zu) v2 %016" PRIx64 "\n", inlen, v2); \

        printf("(%3zu) v3 %016" PRIx64 "\n", inlen, v3); \

    } while(0)

#else

#define TRACE

#endif

int passgen_siphash(

    const void *in,

    const size_t inlen,

    const void *k,

    uint8_t *out,

    const size_t outlen) {

    const unsigned char *ni = (const unsigned char *) in;

    const unsigned char *kk = (const unsigned char *) k;

    assert((outlen == 8) || (outlen == 16));

    uint64_t v0 = UINT64_C(0x736f6d6570736575);

    uint64_t v1 = UINT64_C(0x646f72616e646f6d);

    uint64_t v2 = UINT64_C(0x6c7967656e657261);

    uint64_t v3 = UINT64_C(0x7465646279746573);

    uint64_t k0 = U8TO64_LE(kk);

    uint64_t k1 = U8TO64_LE(kk + 8);

    uint64_t m;

    int i;

    const unsigned char *end = ni + inlen - (inlen % sizeof(uint64_t));

    const int left = inlen & 7;

    uint64_t b = ((uint64_t) inlen) << 56;

    v3 ^= k1;

    v2 ^= k0;

    v1 ^= k1;

    v0 ^= k0;

    if(outlen == 16) 
v1 ^= 0xee8
;

    for(; ni != end; 
ni += 82
) {

        m = U8TO64_LE(ni);

        v3 ^= m;

        TRACE;

        for(i = 0; i < cROUNDS; 
++i4
) 
SIPROUND4
;

        v0 ^= m;

    }

    switch(left) {

        case 7:

            b |= ((uint64_t) ni[6]) << 48;

            // fall through

        case 6:

            b |= ((uint64_t) ni[5]) << 40;

            // fall through

        case 5:

            b |= ((uint64_t) ni[4]) << 32;

            // fall through

        case 4:

            b |= ((uint64_t) ni[3]) << 24;

            // fall through

        case 3:

            b |= ((uint64_t) ni[2]) << 16;

            // fall through

        case 2:

            b |= ((uint64_t) ni[1]) << 8;

            // fall through

        case 1:

            b |= ((uint64_t) ni[0]);

            break;

        case 0:

            break;

    }

    v3 ^= b;

    TRACE;

    for(i = 0; i < cROUNDS; 
++i77.3k
) 
SIPROUND77.3k
;

    v0 ^= b;

    if(outlen == 16)

        v2 ^= 0xee;

    else

        v2 ^= 0xff;

    TRACE;

    for(i = 0; i < dROUNDS; 
++i154k
) 
SIPROUND154k
;

    b = v0 ^ v1 ^ v2 ^ v3;

    U64TO8_LE(out, b);

    if(outlen == 8) 
return 038.6k
;

    v1 ^= 0xdd;

    TRACE;

    for(i = 0; i < dROUNDS; 
++i32
) 
SIPROUND32
;

    b = v0 ^ v1 ^ v2 ^ v3;

    U64TO8_LE(out + 8, b);

    return 0;

}