//
// This confidential and proprietary software may be used only as
// authorised by a licensing agreement from ARM Limited
// (C) COPYRIGHT 2020-2024 ARM Limited
// ALL RIGHTS RESERVED
// The entire notice above must be reproduced on all authorised
// copies and copies may only be made to the extent permitted
// by a licensing agreement from ARM Limited.

ERROR_IF(in_out_t != i8_t && input_zp != 0); // Zero point only for int8_t
ERROR_IF(in_out_t != i8_t && output_zp != 0); // Zero point only for int8_t
ERROR_IF(kernel_y < 1 || kernel_x < 1); // kernel size must be >= 1
ERROR_IF(stride_y < 1 || stride_x < 1);
ERROR_IF(pad_top < 0 || pad_bottom < 0 || pad_left < 0 || pad_right < 0);
// Padding must be less than kernel size to avoid
// a divide-by-zero.
ERROR_IF(pad_right >= kernel_x || pad_left >= kernel_x);
ERROR_IF(pad_top >= kernel_y || pad_bottom >= kernel_y);
ERROR_IF(OH != idiv_check(IH + pad_top + pad_bottom - kernel_y, stride_y) + 1);
ERROR_IF(OW != idiv_check(IW + pad_left + pad_right - kernel_x, stride_x) + 1);

for_each(0 <= n < N, 0 <= oy < OH, 0 <= ox < OW, 0 <= c < C ) {
    in_out_t output_val;
    acc_t acc = 0;
    int count = 0;
    index_t iy = oy * stride_y - pad_top;
    index_t ix = ox * stride_x - pad_left;
    for_each(0 <= ky < kernel_y, 0 <= kx < kernel_x) {
        index_t y = iy + ky;
        index_t x = ix + kx;
        // Only values from the input tensor are used to calculate the
        // average, padding does not count
        if (0 <= y < IH and 0 <= x < IW) {
            count++;
            acc_t value = sign_extend<acc_t>(tensor_read<in_out_t>(input, [N,IH,IW,C], [n,y,x,c]));
            value = apply_sub_s<acc_t>(value, sign_extend<acc_t>(input_zp));
            acc = apply_add_s<acc_t>(acc, value);
        }
    }
    if (is_float(in_out_t)) {
        output_val = acc / static_cast<in_out_t>(count);
    } else {
        scale_t scale = reciprocal_scale(count);
        acc = apply_scale_32(acc, scale.multiplier, scale.shift, false);
        acc = apply_add_s<acc_t>(acc, sign_extend<acc_t>(output_zp));
        acc = apply_clip_s<acc_t>(acc, minimum_s<in_out_t>(), maximum_s<in_out_t>());
        output_val = static_cast<in_out_t>(acc);
    }
    tensor_write<in_out_t>(output, [N,OH,OW,C], [n,oy,ox,c], output_val);
}