/*

* (C) 2018 Jack Lloyd

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#include <botan/internal/chacha.h>

#include <botan/internal/simd_avx2.h>

namespace Botan {

//static

BOTAN_FUNC_ISA("avx2")

void ChaCha::chacha_avx2_x8(uint8_t output[64*8], uint32_t state[16], size_t rounds)

   {

   SIMD_8x32::reset_registers();

   BOTAN_ASSERT(rounds % 2 == 0, "Valid rounds");

   const SIMD_8x32 CTR0 = SIMD_8x32(0, 1, 2, 3, 4, 5, 6, 7);

   const uint32_t C = 0xFFFFFFFF - state[12];

   const SIMD_8x32 CTR1 = SIMD_8x32(0, C < 1, C < 2, C < 3, C < 4, C < 5, C < 6, C < 7);

   SIMD_8x32 R00 = SIMD_8x32::splat(state[ 0]);

   SIMD_8x32 R01 = SIMD_8x32::splat(state[ 1]);

   SIMD_8x32 R02 = SIMD_8x32::splat(state[ 2]);

   SIMD_8x32 R03 = SIMD_8x32::splat(state[ 3]);

   SIMD_8x32 R04 = SIMD_8x32::splat(state[ 4]);

   SIMD_8x32 R05 = SIMD_8x32::splat(state[ 5]);

   SIMD_8x32 R06 = SIMD_8x32::splat(state[ 6]);

   SIMD_8x32 R07 = SIMD_8x32::splat(state[ 7]);

   SIMD_8x32 R08 = SIMD_8x32::splat(state[ 8]);

   SIMD_8x32 R09 = SIMD_8x32::splat(state[ 9]);

   SIMD_8x32 R10 = SIMD_8x32::splat(state[10]);

   SIMD_8x32 R11 = SIMD_8x32::splat(state[11]);

   SIMD_8x32 R12 = SIMD_8x32::splat(state[12]) + CTR0;

   SIMD_8x32 R13 = SIMD_8x32::splat(state[13]) + CTR1;

   SIMD_8x32 R14 = SIMD_8x32::splat(state[14]);

   SIMD_8x32 R15 = SIMD_8x32::splat(state[15]);

   for(size_t r = 0; r != rounds / 2; ++r)

      {

      R00 += R04;

      R01 += R05;

      R02 += R06;

      R03 += R07;

      R12 ^= R00;

      R13 ^= R01;

      R14 ^= R02;

      R15 ^= R03;

      R12 = R12.rotl<16>();

      R13 = R13.rotl<16>();

      R14 = R14.rotl<16>();

      R15 = R15.rotl<16>();

      R08 += R12;

      R09 += R13;

      R10 += R14;

      R11 += R15;

      R04 ^= R08;

      R05 ^= R09;

      R06 ^= R10;

      R07 ^= R11;

      R04 = R04.rotl<12>();

      R05 = R05.rotl<12>();

      R06 = R06.rotl<12>();

      R07 = R07.rotl<12>();

      R00 += R04;

      R01 += R05;

      R02 += R06;

      R03 += R07;

      R12 ^= R00;

      R13 ^= R01;

      R14 ^= R02;

      R15 ^= R03;

      R12 = R12.rotl<8>();

      R13 = R13.rotl<8>();

      R14 = R14.rotl<8>();

      R15 = R15.rotl<8>();

      R08 += R12;

      R09 += R13;

      R10 += R14;

      R11 += R15;

      R04 ^= R08;

      R05 ^= R09;

      R06 ^= R10;

      R07 ^= R11;

      R04 = R04.rotl<7>();

      R05 = R05.rotl<7>();

      R06 = R06.rotl<7>();

      R07 = R07.rotl<7>();

      R00 += R05;

      R01 += R06;

      R02 += R07;

      R03 += R04;

      R15 ^= R00;

      R12 ^= R01;

      R13 ^= R02;

      R14 ^= R03;

      R15 = R15.rotl<16>();

      R12 = R12.rotl<16>();

      R13 = R13.rotl<16>();

      R14 = R14.rotl<16>();

      R10 += R15;

      R11 += R12;

      R08 += R13;

      R09 += R14;

      R05 ^= R10;

      R06 ^= R11;

      R07 ^= R08;

      R04 ^= R09;

      R05 = R05.rotl<12>();

      R06 = R06.rotl<12>();

      R07 = R07.rotl<12>();

      R04 = R04.rotl<12>();

      R00 += R05;

      R01 += R06;

      R02 += R07;

      R03 += R04;

      R15 ^= R00;

      R12 ^= R01;

      R13 ^= R02;

      R14 ^= R03;

      R15 = R15.rotl<8>();

      R12 = R12.rotl<8>();

      R13 = R13.rotl<8>();

      R14 = R14.rotl<8>();

      R10 += R15;

      R11 += R12;

      R08 += R13;

      R09 += R14;

      R05 ^= R10;

      R06 ^= R11;

      R07 ^= R08;

      R04 ^= R09;

      R05 = R05.rotl<7>();

      R06 = R06.rotl<7>();

      R07 = R07.rotl<7>();

      R04 = R04.rotl<7>();

      }

   R00 += SIMD_8x32::splat(state[0]);

   R01 += SIMD_8x32::splat(state[1]);

   R02 += SIMD_8x32::splat(state[2]);

   R03 += SIMD_8x32::splat(state[3]);

   R04 += SIMD_8x32::splat(state[4]);

   R05 += SIMD_8x32::splat(state[5]);

   R06 += SIMD_8x32::splat(state[6]);

   R07 += SIMD_8x32::splat(state[7]);

   R08 += SIMD_8x32::splat(state[8]);

   R09 += SIMD_8x32::splat(state[9]);

   R10 += SIMD_8x32::splat(state[10]);

   R11 += SIMD_8x32::splat(state[11]);

   R12 += SIMD_8x32::splat(state[12]) + CTR0;

   R13 += SIMD_8x32::splat(state[13]) + CTR1;

   R14 += SIMD_8x32::splat(state[14]);

   R15 += SIMD_8x32::splat(state[15]);

   SIMD_8x32::transpose(R00, R01, R02, R03, R04, R05, R06, R07);

   SIMD_8x32::transpose(R08, R09, R10, R11, R12, R13, R14, R15);

   R00.store_le(output);

   R08.store_le(output + 32*1);

   R01.store_le(output + 32*2);

   R09.store_le(output + 32*3);

   R02.store_le(output + 32*4);

   R10.store_le(output + 32*5);

   R03.store_le(output + 32*6);

   R11.store_le(output + 32*7);

   R04.store_le(output + 32*8);

   R12.store_le(output + 32*9);

   R05.store_le(output + 32*10);

   R13.store_le(output + 32*11);

   R06.store_le(output + 32*12);

   R14.store_le(output + 32*13);

   R07.store_le(output + 32*14);

   R15.store_le(output + 32*15);

   SIMD_8x32::zero_registers();

   state[12] += 8;

   if(state[12] < 8)

      state[13]++;

   }

}