/* Copyright (c) 2016 Baidu, Inc. All Rights Reserved.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
==============================================================================*/

#include "operators/math/Gemm.h"
#include <algorithm>
#include <iostream>

namespace paddle_mobile {
namespace operators {
namespace math {
// 将A矩阵分块复制到连续内存
void PackMatrixA(int m, int k, int paddingM, const float *A, int lda,
                 float *buffer) {
  int i, j;
  const float *Aij;
  for (i = 0; i < m - paddingM; i += MR) {
    for (int j = 0; j < k; ++j) {
      Aij = &A(i, j);
      *buffer++ = *Aij;
      *buffer++ = *(Aij + 1);
      *buffer++ = *(Aij + 2);
      *buffer++ = *(Aij + 3);
    }
  }
  if (paddingM != 0) {
    for (j = 0; j < k; ++j) {
      Aij = &A(m - paddingM, j);
      for (i = 0; i < paddingM; ++i) {
        *buffer++ = *(Aij + i);
      }
      for (i = paddingM; i < MR; ++i) {
        *buffer++ = 0;
      }
    }
  }
}

// 将B矩阵分块复制到连续内存
void PackMatrixB(int k, int n, int paddingN, const float *B, int ldb,
                 float *buffer) {
  int i, j;
  for (j = 0; j < n - paddingN; j += NR) {
    const float *Bj = &B(0, j);
    const float *Bj1 = &B(0, j + 1);
    const float *Bj2 = &B(0, j + 2);
    const float *Bj3 = &B(0, j + 3);
    for (i = 0; i < k; ++i) {
      *buffer++ = *Bj++;
      *buffer++ = *Bj1++;
      *buffer++ = *Bj2++;
      *buffer++ = *Bj3++;
    }
  }
  if (paddingN != 0) {
    for (i = 0; i < k; ++i) {
      for (int j = n - paddingN; j < n; ++j) {
        const float *Bij = &B(i, j);
        *buffer++ = *Bij++;
      }
      for (int j = n; j < n + (NR - paddingN); ++j) {
        *buffer++ = 0;
      }
    }
  }
}

// 分块矩阵乘法
void InnerKernel(int m, int n, int k, const float *A, int lda, const float *B,
                 int ldb, float *C, int ldc, int first_time) {
  int Buff_A_M = m;
  int Buff_B_N = n;

  int _mc = m % MR;
  int _nc = n % NR;

  if (_mc != 0) {
    Buff_A_M = m + (MR - _mc);
  }

  if (_nc != 0) {
    Buff_B_N = n + (NR - _nc);
  }

  float packedA[MC * KC];
  static float packedB[KC * NC];

  if (first_time) {
    PackMatrixB(k, n, _nc, B, ldb, packedB);
  }
  PackMatrixA(m, k, _mc, A, lda, packedA);

  int i, j, mc, nc;

  // B 取 4 列, 打包预热
  for (j = 0; j < Buff_B_N; j += NR) {
    nc = (n - j) < NR ? _nc : NR;
    // A 取 4 行，打包预热
    for (i = 0; i < Buff_A_M; i += MR) {
      mc = (m - i) < MR ? _mc : MR;
      AddDot4x4(k, &packedA[i * k], 4, &packedB[j * k], k, &C(i, j), ldc, mc,
                nc);
    }
  }
}

// 计算一个更小的 4 * 4 的 C 矩阵分块
void AddDot4x4(int k, const float *a, int lda, const float *b, int ldb,
               float *C, int ldc, int mc, int nc) {
  float c[16] = {0};
  float reg_a0, reg_a1, reg_a2, reg_a3, reg_b0, reg_b1, reg_b2, reg_b3;

  // // init C
  // float32x4_t cv0 = vdup_n_f32(0.0);
  // float32x4_t cv1 = vdup_n_f32(0.0);
  // float32x4_t cv2 = vdup_n_f32(0.0);
  // float32x4_t cv3 = vdup_n_f32(0.0);

  for (int p = 0; p < k; p += 1) {
    reg_b0 = *b++;
    reg_b1 = *b++;
    reg_b2 = *b++;
    reg_b3 = *b++;

    reg_a0 = *a++;
    reg_a1 = *a++;
    reg_a2 = *a++;
    reg_a3 = *a++;

    // first row
    c[0] += reg_a0 * reg_b0;
    c[1] += reg_a0 * reg_b1;
    c[2] += reg_a0 * reg_b2;
    c[3] += reg_a0 * reg_b3;

    // second row
    c[4] += reg_a1 * reg_b0;
    c[5] += reg_a1 * reg_b1;
    c[6] += reg_a1 * reg_b2;
    c[7] += reg_a1 * reg_b3;

    // third row
    c[8] += reg_a2 * reg_b0;
    c[9] += reg_a2 * reg_b1;
    c[10] += reg_a2 * reg_b2;
    c[11] += reg_a2 * reg_b3;

    // fourth row
    c[12] += reg_a3 * reg_b0;
    c[13] += reg_a3 * reg_b1;
    c[14] += reg_a3 * reg_b2;
    c[15] += reg_a3 * reg_b3;
  }
  int i, j;
  for (i = 0; i < mc; ++i) {
    for (j = 0; j < nc; ++j) {
      C(i, j) += c[i * 4 + j];
    }
  }
}

// 32位 float 矩阵乘法
void sgemm(int m, int n, int k, float alpha, const float *A, int lda,
           const float *B, int ldb, float beta, float *C, int ldc) {
  int i, j, p, mc, nc, kc;

  for (j = 0; j < n; j += NC) {
    nc = min(n - j, NC);
    for (p = 0; p < k; p += KC) {
      kc = min(k - p, KC);
      for (i = 0; i < m; i += MC) {
        mc = min(m - i, MC);
        InnerKernel(mc, nc, kc, &A(i, p), lda, &B(p, j), ldb, &C(i, j), ldc,
                    i == 0);
      }
    }
  }
}

}  // namespace math
}  // namespace operators
}  // namespace paddle_mobile