src/core/NEON/kernels/arm_gemm/transforms/transpose_interleave_common.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

template <unsigned int IntBy, typename TIn, typename TOut>
struct TransposeInterleaveCommon
{
    // Override the moveblock_1xY methods to improve performance
    static inline void moveblock_1x1(const TIn *&in0, TOut *out)
    {
        for(unsigned int i = 0; i < IntBy; i++)
        {
            *out++ = static_cast<TOut>(*in0++);
        }
    }

    static inline void moveblock_1x2(const TIn *&in0, const TIn *&in1, TOut *out)
    {
        for(unsigned int i = 0; i < IntBy; i++)
        {
            *out++ = static_cast<TOut>(*in0++);
        }
        for(unsigned int i = 0; i < IntBy; i++)
        {
            *out++ = static_cast<TOut>(*in1++);
        }
    }

    static inline void moveblock_1x4(const TIn *&in0, const TIn *&in1, const TIn *&in2, const TIn *&in3, TOut *out)
    {
        for(unsigned int i = 0; i < IntBy; i++)
        {
            *out++ = static_cast<TOut>(*in0++);
        }
        for(unsigned int i = 0; i < IntBy; i++)
        {
            *out++ = static_cast<TOut>(*in1++);
        }
        for(unsigned int i = 0; i < IntBy; i++)
        {
            *out++ = static_cast<TOut>(*in2++);
        }
        for(unsigned int i = 0; i < IntBy; i++)
        {
            *out++ = static_cast<TOut>(*in3++);
        }
    }

    static inline void Transform(TOut *out, const TIn *in, const int stride, const int x0, const int xmax, const int k0, const int kmax)
    {
        const auto ldin = stride;

        TOut      *outarray    = out;
        const TIn *inarray     = in;
        TOut      *outptr_base = outarray;
        const TIn *inptr_base  = inarray + x0 + (k0 * ldin);
        int        ldout       = (kmax - k0) * IntBy;

        int k = (kmax - k0);
        for(; k > 3; k -= 4)
        {
            TOut      *outptr = outptr_base;
            const TIn *inptr  = inptr_base;
            const TIn *inptr1 = inptr + ldin;
            const TIn *inptr2 = inptr1 + ldin;
            const TIn *inptr3 = inptr2 + ldin;

            prefetch_3x(inptr);
            prefetch_3x(inptr1);
            prefetch_3x(inptr2);
            prefetch_3x(inptr3);

            outptr_base += IntBy * 4;
            inptr_base += ldin * 4;

            for(int x = (xmax - x0) / IntBy; x > 0; x--)
            {
                moveblock_1x4(inptr, inptr1, inptr2, inptr3, outptr);
                outptr += ldout;
            }
        }

        if(k)
        {
            TOut      *outptr = outptr_base;
            const TIn *inptr  = inptr_base;
            const TIn *inptr1 = inptr + ldin;
            const TIn *inptr2 = inptr1 + ldin;

            prefetch_3x(inptr);
            prefetch_3x(inptr1);
            prefetch_3x(inptr2);

            for(int x = (xmax - x0) / IntBy; x > 0; x--)
            {
                switch(k)
                {
                    case 3:
                        moveblock_1x2(inptr, inptr1, outptr);
                        moveblock_1x1(inptr2, outptr + IntBy * 2);
                        break;

                    case 2:
                        moveblock_1x2(inptr, inptr1, outptr);
                        break;

                    case 1:
                        moveblock_1x1(inptr, outptr);
                        break;

                    default:
                        UNREACHABLE("Impossible.");
                }

                outptr += ldout;
            }
        }

        // Cope with ragged X cases
        const unsigned int overflow = (xmax - x0) % IntBy;
        if(overflow)
        {
            const TIn *inptr_base = inarray + (xmax - overflow) + (k0 * ldin);
            TOut      *outptr     = outarray + ((xmax - x0) / IntBy) * ldout;

            for(int k = (kmax - k0); k > 0; k--)
            {
                const TIn *inptr = inptr_base;
                inptr_base += ldin;

                for(unsigned int x = 0; x < IntBy; x++)
                {
                    TOut val  = (x < overflow) ? static_cast<TOut>(*inptr++) : static_cast<TOut>(0);
                    *outptr++ = val;
                }
            }
        }
    }
};