/******************************************************************************
*
*   Copyright (c) 2020 Intel.
*
*   Licensed under the Apache License, Version 2.0 (the "License");
*   you may not use this file except in compliance with the License.
*   You may obtain a copy of the License at
*
*       http://www.apache.org/licenses/LICENSE-2.0
*
*   Unless required by applicable law or agreed to in writing, software
*   distributed under the License is distributed on an "AS IS" BASIS,
*   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*   See the License for the specific language governing permissions and
*   limitations under the License.
*
*******************************************************************************/

/**
 * @brief xRAN BFP compression/decompression U-plane implementation and interface functions
 *
 * @file xran_compression.cpp
 * @ingroup group_source_xran
 * @author Intel Corporation
 **/

#include "xran_compression.hpp"
#include "xran_bfp_utils.hpp"
#include "xran_bfp_byte_packing_utils.hpp"
#include "xran_compression.h"
#include <complex>
#include <algorithm>
#include <immintrin.h>
#include <limits.h>
#include <cstring>

namespace BFP_UPlane_9b16RB
{
  /// Namespace constants
  const int k_numREReal = 24; /// 12 IQ pairs


  /// Compute exponent value for a set of 16 RB from the maximum absolute value.
  /// Max Abs operates in a loop, executing 4 RB per iteration. The results are
  /// packed into the final output register.
  inline __m512i
  computeExponent_16RB(const BlockFloatCompander::ExpandedData& dataIn, const __m512i totShiftBits)
  {
    __m512i maxAbs = __m512i();
    const __m512i* rawData = reinterpret_cast<const __m512i*>(dataIn.dataExpanded);
    /// Max Abs loop operates on 4RB at a time
#pragma unroll(4)
    for (int n = 0; n < 4; ++n)
    {
      /// Re-order and vertical max abs
      auto maxAbsVert = BlockFloatCompander::maxAbsVertical4RB(rawData[3 * n + 0], rawData[3 * n + 1], rawData[3 * n + 2]);
      /// Horizontal max abs
      auto maxAbsHorz = BlockFloatCompander::horizontalMax4x16(maxAbsVert);
      /// Pack these 4 values into maxAbs
      maxAbs = BlockFloatCompander::slidePermute(maxAbsHorz, maxAbs, n);
    }
    /// Calculate exponent
    const auto maxAbs32 = BlockFloatCompander::maskUpperWord(maxAbs);
    return BlockFloatCompander::expLzCnt(maxAbs32, totShiftBits);
  }


  /// Apply compression to 1 RB
  template<BlockFloatCompander::PackFunction networkBytePack>
  inline void
  applyCompressionN_1RB(const BlockFloatCompander::ExpandedData& dataIn, BlockFloatCompander::CompressedData* dataOut,
                        const int numREOffset, const uint8_t thisExp, const int thisRBExpAddr, const uint16_t rbWriteMask)
  {
    /// Get AVX512 pointer aligned to desired RB
    const __m512i* rawDataIn = reinterpret_cast<const __m512i*>(dataIn.dataExpanded + numREOffset);
    /// Apply the exponent shift
    const auto compData = _mm512_srai_epi16(*rawDataIn, thisExp);
    /// Pack compressed data network byte order
    const auto compDataBytePacked = networkBytePack(compData);
    /// Store exponent first
    dataOut->dataCompressed[thisRBExpAddr] = thisExp;
    /// Now have 1 RB worth of bytes separated into 3 chunks (1 per lane)
    /// Use three offset stores to join
    _mm_mask_storeu_epi8(dataOut->dataCompressed + thisRBExpAddr + 1, rbWriteMask, _mm512_extracti64x2_epi64(compDataBytePacked, 0));
    _mm_mask_storeu_epi8(dataOut->dataCompressed + thisRBExpAddr + 1 + dataIn.iqWidth, rbWriteMask, _mm512_extracti64x2_epi64(compDataBytePacked, 1));
    _mm_mask_storeu_epi8(dataOut->dataCompressed + thisRBExpAddr + 1 + (2 * dataIn.iqWidth), rbWriteMask, _mm512_extracti64x2_epi64(compDataBytePacked, 2));
  }


  /// Calls compression function specific to the number of RB to be executed. For 9, 10, or 12bit iqWidth.
  template<BlockFloatCompander::PackFunction networkBytePack>
  inline void
  compressByAllocN(const BlockFloatCompander::ExpandedData& dataIn, BlockFloatCompander::CompressedData* dataOut,
                   const __m512i totShiftBits, const int totNumBytesPerRB, const uint16_t rbWriteMask)
  {
    const auto exponents = computeExponent_16RB(dataIn, totShiftBits);
#pragma unroll(16)
    for (int n = 0; n < 16; ++n)
    {
      applyCompressionN_1RB<networkBytePack>(dataIn, dataOut, n * k_numREReal, ((uint8_t*)&exponents)[n * 4], n * totNumBytesPerRB, rbWriteMask);
    }
  }


  /// Apply compression to 1 RB
  template<BlockFloatCompander::UnpackFunction networkByteUnpack>
  inline void
  applyExpansionN_1RB(const BlockFloatCompander::CompressedData& dataIn, BlockFloatCompander::ExpandedData* dataOut,
                      const int expAddr, const int thisRBAddr, const int maxExpShift)
  {
    /// Unpack network order packed data
    const auto dataUnpacked = networkByteUnpack(dataIn.dataCompressed + expAddr + 1);
    /// Apply exponent scaling (by appropriate arithmetic shift right)
    const auto dataExpanded = _mm512_srai_epi16(dataUnpacked, maxExpShift - *(dataIn.dataCompressed + expAddr));
    /// Write expanded data to output
    static constexpr uint32_t k_WriteMask = 0x00FFFFFF;
    _mm512_mask_storeu_epi16(dataOut->dataExpanded + thisRBAddr, k_WriteMask, dataExpanded);
  }


  /// Calls compression function specific to the number of RB to be executed. For 9, 10, or 12bit iqWidth.
  template<BlockFloatCompander::UnpackFunction networkByteUnpack>
  inline void
  expandByAllocN(const BlockFloatCompander::CompressedData& dataIn, BlockFloatCompander::ExpandedData* dataOut,
                 const int totNumBytesPerRB, const int maxExpShift)
  {
#pragma unroll(16)
      for (int n = 0; n < 16; ++n)
      {
        applyExpansionN_1RB<networkByteUnpack>(dataIn, dataOut, n * totNumBytesPerRB, n * k_numREReal, maxExpShift);
      }
  }
}



/// Main kernel function for compression.
/// Starts by determining iqWidth specific parameters and functions.
void
BlockFloatCompander::BFPCompressUserPlaneAvx512_9b16RB(const ExpandedData& dataIn, CompressedData* dataOut)
{
  /// Compensation for extra zeros in 32b leading zero count when computing exponent
  const auto totShiftBits9 = _mm512_set1_epi32(24);

  /// Total number of compressed bytes per RB for each iqWidth option
  constexpr int totNumBytesPerRB9 = 28;

  /// Compressed data write mask for each iqWidth option
  constexpr uint16_t rbWriteMask9 = 0x01FF;

  BFP_UPlane_9b16RB::compressByAllocN<BlockFloatCompander::networkBytePack9b>(dataIn, dataOut, totShiftBits9, totNumBytesPerRB9, rbWriteMask9);
}



/// Main kernel function for expansion.
/// Starts by determining iqWidth specific parameters and functions.
void
BlockFloatCompander::BFPExpandUserPlaneAvx512_9b16RB(const CompressedData& dataIn, ExpandedData* dataOut)
{
  constexpr int k_totNumBytesPerRB9 = 28;
  constexpr int k_maxExpShift9 = 7;
  BFP_UPlane_9b16RB::expandByAllocN<BlockFloatCompander::networkByteUnpack9b>(dataIn, dataOut, k_totNumBytesPerRB9, k_maxExpShift9);
}