/*
 * Copyright 2023 Google LLC
 *
 * 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.
 */

#include <riscv_vector.h>
#include <string.h>

#include "iree/builtins/ukernel/mmt4d_internal.h"

// Calculate the dot product of two int8 vectors using RVV
static iree_uk_int32_t dot_product_rvv(const iree_uk_int8_t* u,
                                       const iree_uk_int8_t* w, int n) {
  size_t vl;
  // auxiliary variables
  vint8m4_t vu, vw;
  vint16m8_t vx;
  vint32m1_t v_sum;
  iree_uk_int32_t sum = 0;
  for (size_t i = 0; i < n; i += vl) {
    vl = vsetvl_e8m4(n - i);
    vu = vle8_v_i8m4(u + i, vl);             // load
    vw = vle8_v_i8m4(w + i, vl);             // load
    vx = vwmul(vu, vw, vl);                  // multiply
    v_sum = vmv_s(v_sum, 0, vl);             // init
    v_sum = vwredsum(v_sum, vx, v_sum, vl);  // sum
    sum += vmv_x(v_sum);
  }
  return sum;
}

// RVV implementation of matmul tile, i8*i8->i32 case.
static void iree_uk_mmt4d_tile_i8i8i32_rvv(
    void* out_tile_untyped, const void* lhs_panel_untyped,
    const void* rhs_panel_untyped, const iree_uk_mmt4d_params_t* params) {
  iree_uk_int32_t* out_tile = out_tile_untyped;
  const iree_uk_int8_t* lhs_panel = lhs_panel_untyped;
  const iree_uk_int8_t* rhs_panel = rhs_panel_untyped;
  iree_uk_int16_t M0 = params->M0;
  iree_uk_int16_t N0 = params->N0;
  iree_uk_int16_t K0 = params->K0;
  // Initialize the accumulator tile.
  if (!(params->flags & IREE_UK_FLAG_MMT4D_ACCUMULATE)) {
    memset(out_tile, 0, M0 * N0 * sizeof(iree_uk_int32_t));
  }
  // Accumulation loop.
  for (iree_uk_index_t k = 0; k < params->K; ++k) {
    for (iree_uk_index_t i0 = 0; i0 < M0; ++i0) {
      for (iree_uk_index_t j0 = 0; j0 < N0; ++j0) {
        out_tile[i0 * N0 + j0] +=
            dot_product_rvv(lhs_panel + i0 * K0, rhs_panel + j0 * K0, K0);
      }
    }
    lhs_panel += M0 * K0;
    rhs_panel += N0 * K0;
  }
}

// Generic implementation of matmul tile, f32*f32->f32 case.
static void iree_uk_mmt4d_tile_f32f32f32_generic(
    void* out_tile_untyped, const void* lhs_panel_untyped,
    const void* rhs_panel_untyped, const iree_uk_mmt4d_params_t* params) {
  float* out_tile = out_tile_untyped;
  const float* lhs_panel = lhs_panel_untyped;
  const float* rhs_panel = rhs_panel_untyped;
  iree_uk_int16_t M0 = params->M0;
  iree_uk_int16_t N0 = params->N0;
  iree_uk_int16_t K0 = params->K0;
  // Initialize the local accumulator tile.
  float acc[iree_uk_mmt4d_tile_generic_max_bytes / sizeof(*out_tile)];
  if (params->flags & IREE_UK_FLAG_MMT4D_ACCUMULATE) {
    for (int i = 0; i < M0 * N0; ++i) acc[i] = out_tile[i];
  } else {
    for (int i = 0; i < M0 * N0; ++i) acc[i] = 0;
  }
  // Accumulation loop.
  for (iree_uk_index_t k = 0; k < params->K; ++k) {
    for (iree_uk_index_t i0 = 0; i0 < M0; ++i0) {
      for (iree_uk_index_t j0 = 0; j0 < N0; ++j0) {
        for (iree_uk_index_t k0 = 0; k0 < K0; ++k0) {
          float lhs_val = lhs_panel[i0 * K0 + k0];
          float rhs_val = rhs_panel[j0 * K0 + k0];
          acc[i0 * N0 + j0] += lhs_val * rhs_val;
        }
      }
    }
    lhs_panel += M0 * K0;
    rhs_panel += N0 * K0;
  }
  // Store the local accumulator tile to the destination.
  for (int i = 0; i < M0 * N0; ++i) out_tile[i] = acc[i];
}

iree_uk_mmt4d_tile_func_t iree_uk_mmt4d_select_tile_func(
    const iree_uk_mmt4d_params_t* params) {
  // TODO(lundong): to be replaced with Kelvin
  switch (iree_uk_mmt4d_type(params->flags)) {
    case iree_uk_mmt4d_type_f32f32f32:
      return iree_uk_mmt4d_tile_f32f32f32_generic;
    case iree_uk_mmt4d_type_i8i8i32:
      return iree_uk_mmt4d_tile_i8i8i32_rvv;
    default:
      // shouldn't happen, validated earlier.
      IREE_UK_ASSUME_UNREACHABLE;
      return 0;
  }
}