Method kern_naive

dnn/src/naive/warp_perspective/opr_impl.cpp:131–246

template <typename ctype, typename mtype>
void WarpPerspectiveForwardImpl::kern_naive(
        const KernParam<ctype, mtype>& kern_param, size_t task_id) {
    MEGDNN_MARK_USED_VAR(kern_param);
    MIDOUT_BEGIN(megdnn_naive_warpperspective, ctype, mtype, midout_iv(0)) {
        UNPACK_WARP_PERSPECTIVE_FWD_KERN_PARAM(kern_param);
        MEGDNN_MARK_USED_VAR(N_MAT);
        //! strides of C, H, W on src and dst
        size_t sstrd[3], dstrd[3];
        auto set_sstrd = [&](size_t s0, size_t s1, size_t s2) {
            sstrd[0] = s0;
            sstrd[1] = s1;
            sstrd[2] = s2;
        };
        auto set_dstrd = [&](size_t s0, size_t s1, size_t s2) {
            dstrd[0] = s0;
            dstrd[1] = s1;
            dstrd[2] = s2;
        };
        switch (kern_param.format) {
            case Format::NCHW:
            case Format::NCHW4:
                set_sstrd(IH * IW, IW, 1);
                set_dstrd(OH * OW, OW, 1);
                break;
            case Format::NHWC:
                set_sstrd(1, IW * C, C);
                set_dstrd(1, OW * C, C);
                break;
            default:
                megdnn_throw("bad format");
        }

        bool is_nchw4 = kern_param.format == Format::NCHW4;
        auto visit_src = [&sptr, sstrd, is_nchw4](size_t c, int h, int w) -> float {
            if (!is_nchw4)
                return sptr[sstrd[0] * c + sstrd[1] * h + sstrd[2] * w];
            else
                return sptr
                        [((sstrd[0] * (c >> 2) + sstrd[1] * h + sstrd[2] * w) << 2) +
                         (c & 0b11)];
        };
        auto visit_src_bd = [&sptr, sstrd, border_val, is_nchw4](
                                    size_t c, int h, int w) -> float {
            if (h != -1 && w != -1) {
                if (!is_nchw4) {
                    return sptr[sstrd[0] * c + sstrd[1] * h + sstrd[2] * w];
                } else {
                    return sptr
                            [((sstrd[0] * (c >> 2) + sstrd[1] * h + sstrd[2] * w)
                              << 2) +
                             (c & 0b11)];
                }
            } else
                return border_val;
        };
        auto visit_dst = [&dptr, dstrd, is_nchw4](size_t c, int h, int w) -> ctype& {
            if (!is_nchw4)
                return dptr[dstrd[0] * c + dstrd[1] * h + dstrd[2] * w];