int resize_with_halide()
{
Halide::ImageParam input {Halide::type_of<uint8_t>(), 3};
//_/_/_/ load a source image and repeat its edges
Halide::Func src_image {};
src_image = Halide::BoundaryConditions::repeat_edge(input);
//_/_/_/ describe algorithm
Halide::Param<float> src_rows {};
Halide::Param<float> src_cols {};
Halide::Param<float> dst_rows {};
Halide::Param<float> dst_cols {};
// const float sc = 500.0f/4999;//static_cast<float>(src_cols.get()) / dst_cols.get();
// const float sr = 350.0f/3499;//static_cast<float>(src_rows.get()) / dst_rows.get();
const auto sc = src_cols / dst_cols;
const auto sr = src_rows / dst_rows;
Halide::Var i {};
Halide::Var j {};
Halide::Var c {};
auto fj = j * sr;
auto cj0 = Halide::cast<int>(fj);
auto cj1 = cj0 + 1;
auto dj = fj - cj0;
auto fi = i * sc;
auto ci0 = Halide::cast<int>(fi);
auto ci1 = ci0 + 1;
auto di = fi - ci0;
const auto c0 = (1.0f - dj) * (1.0f - di);
const auto c1 = (1.0f - dj) * di;
const auto c2 = dj * (1.0f - di);
const auto c3 = dj * di;
const auto& src_pixel0 = src_image(ci0, cj0, c);
const auto& src_pixel1 = src_image(ci1, cj0, c);
const auto& src_pixel2 = src_image(ci0, cj1, c);
const auto& src_pixel3 = src_image(ci1, cj1, c);
Halide::Func resize {};
resize(i, j, c) = Halide::saturating_cast<uint8_t>(c0 * src_pixel0 + c1 * src_pixel1 + c2 * src_pixel2 + c3 * src_pixel3);
//_/_/_/ describe scheduling
Halide::Var i_inner, j_inner;
auto x_vector_size = 64;
resize.compute_root();
resize.tile(i, j, i_inner, j_inner, x_vector_size, 4).vectorize(i_inner, 16).parallel(j);
//_/_/_/ save a static library
const auto path = "/Users/kumada/Projects/cct_blog/halide/sample_4/sample_4/resize";
resize.compile_to_static_library(
path,
{input, src_rows, src_cols, dst_rows, dst_cols},
"resize");
return 1;
}
