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// Copyright 2015 The Gemmlowp Authors. All Rights Reserved.
//
// 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.
// kernel_reference.h: a reference kernel for CPU architectures where we don't
// have optimized kernels yet. Also useful for testing, as it's templatized
// to have any arbitrary format, allowing tests to cover all sorts of corner
// cases.
#ifndef GEMMLOWP_INTERNAL_KERNEL_REFERENCE_H_
#define GEMMLOWP_INTERNAL_KERNEL_REFERENCE_H_
#include "kernel.h"
#include <cstdio>
#include <cstring>
namespace gemmlowp {
// This kernel is templatized in an arbitrary Format template parameter,
// allowing it to have any arbitrary format.
template <typename tFormat>
struct ReferenceKernel : KernelBase {
typedef tFormat Format;
const char* Name() const override {
static char buf[256];
snprintf(buf, sizeof(buf),
"reference(Lhs: %d cells %dx%d %s, Rhs: %d cells %dx%d %s)",
Format::Lhs::kCells, Format::Lhs::Cell::kWidth,
Format::Lhs::Cell::kDepth,
CellOrderName(Format::Lhs::Cell::kOrder), Format::Rhs::kCells,
Format::Rhs::Cell::kDepth, Format::Rhs::Cell::kWidth,
CellOrderName(Format::Rhs::Cell::kOrder));
return buf;
}
void Run(std::int32_t* dst_ptr, std::size_t dst_row_stride,
std::size_t dst_col_stride, const std::uint8_t* lhs_ptr,
const std::uint8_t* rhs_ptr, std::size_t start_depth,
std::size_t run_depth) const override {
std::int32_t accumulator[Format::kRows * Format::kCols];
memset(accumulator, 0, sizeof(accumulator));
const int run_depth_cells = static_cast<int>(run_depth / Format::kDepth);
// The outer loop is over the depth dimension.
for (int dc = 0; dc < run_depth_cells; dc++) {
// The next two loops are over cells of the Lhs (stacked vertically),
// and over cells of the Rhs (stacked horizontally).
for (int rc = 0; rc < Format::Lhs::kCells; rc++) {
const std::uint8_t* lhs_cell_ptr =
lhs_ptr + (dc * Format::Lhs::kCells + rc) *
Format::Lhs::Cell::kWidth * Format::kDepth;
for (int cc = 0; cc < Format::Rhs::kCells; cc++) {
const std::uint8_t* rhs_cell_ptr =
rhs_ptr + (dc * Format::Rhs::kCells + cc) *
Format::Rhs::Cell::kWidth * Format::kDepth;
// Now we are inside one cell of the Lhs and inside one cell
// of the Rhs, so the remaining inner loops are just
// traditional three loops of matrix multiplication.
for (int di = 0; di < Format::kDepth; di++) {
for (int ri = 0; ri < Format::Lhs::Cell::kWidth; ri++) {
for (int ci = 0; ci < Format::Rhs::Cell::kWidth; ci++) {
const std::uint8_t* lhs_coeff_ptr =
lhs_cell_ptr +
OffsetIntoCell<typename Format::Lhs::Cell>(ri, di);
const std::uint8_t* rhs_coeff_ptr =
rhs_cell_ptr +
OffsetIntoCell<typename Format::Rhs::Cell>(ci, di);
std::int32_t* accumulator_coeff_ptr =
accumulator + (ri + rc * Format::Lhs::Cell::kWidth) +
(ci + cc * Format::Rhs::Cell::kWidth) * Format::kRows;
*accumulator_coeff_ptr +=
std::int32_t(*lhs_coeff_ptr) * std::int32_t(*rhs_coeff_ptr);
}
}
}
}
}
}
if (start_depth == 0) {
// start_depth == 0 means we haven't accumulated anything yet, so we need
// to overwrite the accumulator, as it hasn't been initialized to zero.
for (int r = 0; r < Format::kRows; r++) {
for (int c = 0; c < Format::kCols; c++) {
dst_ptr[r * dst_row_stride + c * dst_col_stride] =
accumulator[r + c * Format::kRows];
}
}
} else {
// We have already accumulated stuff, so we need to continue accumulating
// instead of just overwriting.
for (int r = 0; r < Format::kRows; r++) {
for (int c = 0; c < Format::kCols; c++) {
dst_ptr[r * dst_row_stride + c * dst_col_stride] +=
accumulator[r + c * Format::kRows];
}
}
}
}
};
} // namespace gemmlowp
#endif // GEMMLOWP_INTERNAL_KERNEL_REFERENCE_H_