/*
 *  Copyright (c) 2016-2020 Positive Technologies, https://www.ptsecurity.com,
 *  Fast Positive Hash.
 *
 *  Portions Copyright (c) 2010-2020 Leonid Yuriev <leo@yuriev.ru>,
 *  The 1Hippeus project (t1h).
 *
 *  This software is provided 'as-is', without any express or implied
 *  warranty. In no event will the authors be held liable for any damages
 *  arising from the use of this software.
 *
 *  Permission is granted to anyone to use this software for any purpose,
 *  including commercial applications, and to alter it and redistribute it
 *  freely, subject to the following restrictions:
 *
 *  1. The origin of this software must not be misrepresented; you must not
 *     claim that you wrote the original software. If you use this software
 *     in a product, an acknowledgement in the product documentation would be
 *     appreciated but is not required.
 *  2. Altered source versions must be plainly marked as such, and must not be
 *     misrepresented as being the original software.
 *  3. This notice may not be removed or altered from any source distribution.
 */

/*
 * t1ha = { Fast Positive Hash, aka "Позитивный Хэш" }
 * by [Positive Technologies](https://www.ptsecurity.ru)
 *
 * Briefly, it is a 64-bit Hash Function:
 *  1. Created for 64-bit little-endian platforms, in predominantly for x86_64,
 *     but portable and without penalties it can run on any 64-bit CPU.
 *  2. In most cases up to 15% faster than City64, xxHash, mum-hash, metro-hash
 *     and all others portable hash-functions (which do not use specific
 *     hardware tricks).
 *  3. Not suitable for cryptography.
 *
 * The Future will (be) Positive. Всё будет хорошо.
 *
 * ACKNOWLEDGEMENT:
 * The t1ha was originally developed by Leonid Yuriev (Леонид Юрьев)
 * for The 1Hippeus project - zerocopy messaging in the spirit of Sparta!
 */

#include "t1ha_bits.h"
#include "t1ha_selfcheck.h"

#if T1HA0_AESNI_AVAILABLE

uint64_t T1HA_IA32AES_NAME(const void *data, uint32_t len) {

  uint64_t a = 0;
  uint64_t b = len;

  if (likely(len > 32)) {

    __m128i x = _mm_set_epi64x(a, b);
    __m128i y = _mm_aesenc_si128(x, _mm_set_epi64x(prime_0, prime_1));

    const __m128i       *v = (const __m128i *)data;
    const __m128i *const detent =
        (const __m128i *)((const uint8_t *)data + (len & ~15ul));
    data = detent;

    if (len & 16) {

      x = _mm_add_epi64(x, _mm_loadu_si128(v++));
      y = _mm_aesenc_si128(x, y);

    }

    len &= 15;

    if (v + 7 < detent) {

      __m128i salt = y;
      do {

        __m128i t = _mm_aesenc_si128(_mm_loadu_si128(v++), salt);
        t = _mm_aesdec_si128(t, _mm_loadu_si128(v++));
        t = _mm_aesdec_si128(t, _mm_loadu_si128(v++));
        t = _mm_aesdec_si128(t, _mm_loadu_si128(v++));

        t = _mm_aesdec_si128(t, _mm_loadu_si128(v++));
        t = _mm_aesdec_si128(t, _mm_loadu_si128(v++));
        t = _mm_aesdec_si128(t, _mm_loadu_si128(v++));
        t = _mm_aesdec_si128(t, _mm_loadu_si128(v++));

        salt = _mm_add_epi64(salt, _mm_set_epi64x(prime_5, prime_6));
        t = _mm_aesenc_si128(x, t);
        x = _mm_add_epi64(y, x);
        y = t;

      } while (v + 7 < detent);

    }

    while (v < detent) {

      __m128i v0y = _mm_add_epi64(y, _mm_loadu_si128(v++));
      __m128i v1x = _mm_sub_epi64(x, _mm_loadu_si128(v++));
      x = _mm_aesdec_si128(x, v0y);
      y = _mm_aesdec_si128(y, v1x);

    }

    x = _mm_add_epi64(_mm_aesdec_si128(x, _mm_aesenc_si128(y, x)), y);
  #if defined(__x86_64__) || defined(_M_X64)
    #if defined(__SSE4_1__) || defined(__AVX__)
    a = _mm_extract_epi64(x, 0);
    b = _mm_extract_epi64(x, 1);
    #else
    a = _mm_cvtsi128_si64(x);
    b = _mm_cvtsi128_si64(_mm_unpackhi_epi64(x, x));
    #endif
  #else
    #if defined(__SSE4_1__) || defined(__AVX__)
    a = (uint32_t)_mm_extract_epi32(x, 0) | (uint64_t)_mm_extract_epi32(x, 1)
                                                << 32;
    b = (uint32_t)_mm_extract_epi32(x, 2) | (uint64_t)_mm_extract_epi32(x, 3)
                                                << 32;
    #else
    a = (uint32_t)_mm_cvtsi128_si32(x);
    a |= (uint64_t)_mm_cvtsi128_si32(_mm_shuffle_epi32(x, 1)) << 32;
    x = _mm_unpackhi_epi64(x, x);
    b = (uint32_t)_mm_cvtsi128_si32(x);
    b |= (uint64_t)_mm_cvtsi128_si32(_mm_shuffle_epi32(x, 1)) << 32;
    #endif
  #endif
  #ifdef __AVX__
    _mm256_zeroupper();
  #elif !(defined(_X86_64_) || defined(__x86_64__) || defined(_M_X64) || \
          defined(__e2k__))
    _mm_empty();
  #endif

  }

  const uint64_t *v = (const uint64_t *)data;
  switch (len) {

    default:
      mixup64(&a, &b, fetch64_le_unaligned(v++), prime_4);
    /* fall through */
    case 24:
    case 23:
    case 22:
    case 21:
    case 20:
    case 19:
    case 18:
    case 17:
      mixup64(&b, &a, fetch64_le_unaligned(v++), prime_3);
    /* fall through */
    case 16:
    case 15:
    case 14:
    case 13:
    case 12:
    case 11:
    case 10:
    case 9:
      mixup64(&a, &b, fetch64_le_unaligned(v++), prime_2);
    /* fall through */
    case 8:
    case 7:
    case 6:
    case 5:
    case 4:
    case 3:
    case 2:
    case 1:
      mixup64(&b, &a, tail64_le_unaligned(v, len), prime_1);
    /* fall through */
    case 0:
      return final64(a, b);

  }

}

#endif                                             /* T1HA0_AESNI_AVAILABLE */
#undef T1HA_IA32AES_NAME