/*
 * Copyright (c) 2017 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.
 */
#include "helpers.h"

#if defined(POOL_AVG)
#define POOL_OP(x, y) ((x) + (y))
#else /* defined(POOL_AVG) */
#define POOL_OP(x, y) (max((x), (y)))
#endif /* defined(POOL_AVG) */

#define DIV_OP(x, y) (x * (1.f / y))

#if defined(POOL_L2)
#error "L2 pooling is not supported"
#endif /* defined(POOL_L2) */

int calculate_avg_scale(const int pool_size, const int upper_bound_w, const int upper_bound_h,
                        const int pad_x, const int pad_y, const int stride_x, const int stride_y)
{
    int       start_x = get_global_id(0) * stride_x - pad_x;
    int       start_y = get_global_id(1) * stride_y - pad_y;
    const int end_x   = min(start_x + pool_size, upper_bound_w);
    const int end_y   = min(start_y + pool_size, upper_bound_h);
#if defined(EXCLUDE_PADDING)
    start_x = max(0, start_x);
    start_y = max(0, start_y);
#endif /* defined(EXCLUDE_PADDING) */
    return ((end_y - start_y) * (end_x - start_x));
}

/** Performs a pooling function of pool size equal to N
 *
 * @note Pool size must be passed using -DPOOL_SIZE e.g. -DPOOL_SIZE=13;
 * @note In case of average pooling the following information must be passed at compile time:
 *       -DPOOL_AVG must be provided otherwise max pooling will be performed.
 *       -DMAX_WIDTH and -DMAX_HEIGHT which are the maximum accessible indeces in x and y dimensions (width + pad)
 *       -DSTRIDE_X and -DSTRIDE_Y which are the steps of the window along the x and y directions
 *       -DPAD_X and -DPAD_Y which are the pooling paddings in x and y dimension
 *
 * @param[in]  input_ptr                            Pointer to the source image. Supported data types: QASYMM8
 * @param[in]  input_stride_x                       Stride of the source image in X dimension (in bytes)
 * @param[in]  input_step_x                         input_stride_x * number of elements along X processed per workitem(in bytes)
 * @param[in]  input_stride_y                       Stride of the source image in Y dimension (in bytes)
 * @param[in]  input_step_y                         input_stride_y * number of elements along Y processed per workitem(in bytes)
 * @param[in]  input_stride_z                       Stride of the source tensor in Z dimension (in bytes)
 * @param[in]  input_step_z                         input_stride_z * number of elements along Z processed per workitem(in bytes)
 * @param[in]  input_offset_first_element_in_bytes  The offset of the first element in the source image
 * @param[out] output_ptr                           Pointer to the destination image. Supported data types: same as @p input_ptr
 * @param[in]  output_stride_x                      Stride of the destination image in X dimension (in bytes)
 * @param[in]  output_step_x                        output_stride_x * number of elements along X processed per workitem(in bytes)
 * @param[in]  output_stride_y                      Stride of the destination image in Y dimension (in bytes)
 * @param[in]  output_step_y                        output_stride_y * number of elements along Y processed per workitem(in bytes)
 * @param[in]  output_stride_z                      Stride of the source tensor in Z dimension (in bytes)
 * @param[in]  output_step_z                        output_stride_z * number of elements along Z processed per workitem(in bytes)
 * @param[in]  output_offset_first_element_in_bytes The offset of the first element in the destination image
 */
__kernel void pooling_layer_N_quantized(
    TENSOR3D_DECLARATION(input),
    TENSOR3D_DECLARATION(output))
{
    // Get pixels pointer
    Tensor3D input  = CONVERT_TO_TENSOR3D_STRUCT(input);
    Tensor3D output = CONVERT_TO_TENSOR3D_STRUCT(output);

    int8 vdata = 0;
    int  sdata = 0;

    // Load data
    for(int y = 0; y < POOL_SIZE; y++)
    {
        int x = 0;
        for(; x <= ((int)POOL_SIZE - 8); x += 8)
        {
            uchar8 data = vload8(0, (__global uchar *)tensor3D_offset(&input, x, y, 0));
            int8 data0  = convert_int8(data);
            vdata       = POOL_OP(vdata, data0);
        }

        // Leftover
        for(; x < (int)POOL_SIZE; ++x)
        {
            uchar data = *((__global uchar *)tensor3D_offset(&input, x, y, 0));
            int data0  = convert_int(data);
            sdata      = POOL_OP(sdata, data0);
        }
    }

    // Reduce result
    int4 reduce4 = POOL_OP(vdata.s0123, vdata.s4567);
    int2 reduce2 = POOL_OP(reduce4.s01, reduce4.s23);
    int  res     = POOL_OP(reduce2.s0, reduce2.s1);
    res          = POOL_OP(res, sdata);

#if defined(POOL_AVG)
    res = DIV_OP(res, calculate_avg_scale(POOL_SIZE, MAX_WIDTH, MAX_HEIGHT, PAD_X, PAD_Y, STRIDE_X, STRIDE_Y));
#endif /* defined(POOL_AVG) */

    // Store result
    *(__global uchar *)output.ptr = convert_uchar(res);
}