/*
* CLMUL hook
* (C) 2013 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/

#include <botan/internal/clmul.h>
#include <immintrin.h>
#include <wmmintrin.h>

namespace Botan {

void gcm_multiply_clmul(byte x[16], const byte H[16])
   {
   /*
   * Algorithms 1 and 5 from Intel's CLMUL guide
   */
   const __m128i BSWAP_MASK = _mm_set_epi8(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15);

   __m128i a = _mm_loadu_si128(reinterpret_cast<const __m128i*>(&x[0]));
   __m128i b = _mm_loadu_si128(reinterpret_cast<const __m128i*>(&H[0]));

   a = _mm_shuffle_epi8(a, BSWAP_MASK);
   b = _mm_shuffle_epi8(b, BSWAP_MASK);

   __m128i T0, T1, T2, T3, T4, T5;

   T0 = _mm_clmulepi64_si128(a, b, 0x00);
   T1 = _mm_clmulepi64_si128(a, b, 0x01);
   T2 = _mm_clmulepi64_si128(a, b, 0x10);
   T3 = _mm_clmulepi64_si128(a, b, 0x11);

   T1 = _mm_xor_si128(T1, T2);
   T2 = _mm_slli_si128(T1, 8);
   T1 = _mm_srli_si128(T1, 8);
   T0 = _mm_xor_si128(T0, T2);
   T3 = _mm_xor_si128(T3, T1);

   T4 = _mm_srli_epi32(T0, 31);
   T0 = _mm_slli_epi32(T0, 1);

   T5 = _mm_srli_epi32(T3, 31);
   T3 = _mm_slli_epi32(T3, 1);

   T2 = _mm_srli_si128(T4, 12);
   T5 = _mm_slli_si128(T5, 4);
   T4 = _mm_slli_si128(T4, 4);
   T0 = _mm_or_si128(T0, T4);
   T3 = _mm_or_si128(T3, T5);
   T3 = _mm_or_si128(T3, T2);

   T4 = _mm_slli_epi32(T0, 31);
   T5 = _mm_slli_epi32(T0, 30);
   T2 = _mm_slli_epi32(T0, 25);

   T4 = _mm_xor_si128(T4, T5);
   T4 = _mm_xor_si128(T4, T2);
   T5 = _mm_srli_si128(T4, 4);
   T3 = _mm_xor_si128(T3, T5);
   T4 = _mm_slli_si128(T4, 12);
   T0 = _mm_xor_si128(T0, T4);
   T3 = _mm_xor_si128(T3, T0);

   T4 = _mm_srli_epi32(T0, 1);
   T1 = _mm_srli_epi32(T0, 2);
   T2 = _mm_srli_epi32(T0, 7);
   T3 = _mm_xor_si128(T3, T1);
   T3 = _mm_xor_si128(T3, T2);
   T3 = _mm_xor_si128(T3, T4);

   T3 = _mm_shuffle_epi8(T3, BSWAP_MASK);

   _mm_storeu_si128(reinterpret_cast<__m128i*>(&x[0]), T3);
   }

}