src/core/NEON/kernels/arm_gemm/transform.hpp

/*
 * Copyright (c) 2017-2018 ARM Limited.
 *
 * SPDX-License-Identifier: MIT
 *
 * 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.
 */
#pragma once

/*
 * Generic transform.
 *
 * Assuming the untransposed case, this works by first reading <BlockBy>
 * consecutive values from the first input row.  This same number of values
 * are then read from the next <IntBy-1> rows.  Now return to the first
 * input row and repeat.
 *
 * Need to cope with the work requested in either dimension not actually
 * being a multiple of the block sizes.
 */
template <unsigned IntBy, unsigned int BlockBy, bool Transposed, size_t TOutSize, size_t TInSize>
struct TransformImpl
{
    template <typename TOut, typename TIn>
    static void Transform(TOut *out, const TIn *const in, const int stride,
                          const int y0, const int ymax, const int x0, const int xmax)
    {
        const int n_whole_y_blocks = (ymax - y0) / IntBy;
        const int y_remainders     = (ymax - y0) % IntBy;
        const int n_y_blocks       = n_whole_y_blocks + (y_remainders ? 1 : 0);

        const int n_whole_x_blocks = (xmax - x0) / BlockBy;
        const int x_remainders     = (xmax - x0) % BlockBy;
        const int n_x_blocks       = n_whole_x_blocks + (x_remainders ? 1 : 0);

        // "Y" loop: advance down the rows of the source IntBy rows at a time.
        // Set up fill_rows to show the number rows to copy from, and blank_rows
        // for the number of blank rows to add.
        for(int y_block = 0; y_block < n_y_blocks; y_block++)
        {
            int fill_rows  = (y_block < n_whole_y_blocks) ? IntBy : y_remainders;
            int blank_rows = IntBy - fill_rows;

            int y_base = y0 + (y_block * IntBy);

            // So now advance along this block of rows, BlockBy columns at a time.
            for(int x_block = 0; x_block < n_x_blocks; x_block++)
            {
                int fill_cols  = (x_block < n_whole_x_blocks) ? BlockBy : x_remainders;
                int blank_cols = BlockBy - fill_cols;

                int x_base = x0 + (x_block * BlockBy);

                for(int row = 0; row < fill_rows; row++)
                {
                    for(int col = 0; col < fill_cols; col++)
                    {
                        // In-range copy.  If it's transposed, we reverse the sense of rows and columns here.
                        if(Transposed)
                        {
                            *out++ = static_cast<TOut>(in[(x_base + col) * stride + y_base + row]);
                        }
                        else
                        {
                            *out++ = static_cast<TOut>(in[(y_base + row) * stride + x_base + col]);
                        }
                    }
                    // "col" tail - row is in range but column is out of range.
                    for(int col = 0; col < blank_cols; col++)
                    {
                        *out++ = static_cast<TOut>(0);
                    }
                }
                // "row" tail - row is out of range so fill with zeros always.
                for(int row = 0; row < blank_rows; row++)
                {
                    for(int col = 0; col < (fill_cols + blank_cols); col++)
                    {
                        *out++ = static_cast<TOut>(0);
                    }
                }
            }
        }
    }

    template <typename T>
    static inline void Transform(T *out, const T *const in, const int stride,
                                 const int k0, const int kmax, const int x0, const int xmax)
    {
        Transform<T, T>(out, in, stride, k0, kmax, x0, xmax);
    }
};

/*****************************************************************************/
template <unsigned int IntBy, unsigned int BlockBy, bool Transposed, typename TOut, typename TIn>
void Transform(
    TOut *out, const TIn *const in, const int stride,
    const int k0, const int kmax, const int x0, const int xmax)
{
    // Redirect to a specialised implementation predicated on argument size.
    TransformImpl<IntBy, BlockBy, Transposed, sizeof(TOut), sizeof(TIn)>::Transform(
        out, in, stride, k0, kmax, x0, xmax);
}
/*****************************************************************************/

#include "transforms/list.hpp"