Program Listing for File Halide_CodeSample.cpp

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// halide_targetcode/sample.cpp
#include "Halide.h"

using namespace Halide;

class SamplePipeline : public Generator<SamplePipeline> {
  public:
    // Input: 8-bit grayscale image
    Input<Buffer<uint8_t>> input{ "input", 2 };

    // Optional params (can be set via PARAMS in add_halide_library)
    GeneratorParam<int>  gain{ "gain", 1 }; // multiply factor
    GeneratorParam<int>  bias{ "bias", 1 }; // add bias
    GeneratorParam<bool> do_clamp{ "do_clamp", true };

    // Output: 8-bit grayscale image
    Output<Buffer<uint8_t>> output{ "output", 2 };

    // Vars
    Var  x{ "x" }, y{ "y" };
    Func f{ "f" };

    void
    generate()
    {
        // Simple pixel transform: out = clamp(in*gain + bias)
        Expr v = cast<int>(input(x, y)) * gain + bias;

        if (do_clamp) {
            v = clamp(v, 0, 255);
        }

        f(x, y)      = cast<uint8_t>(v);
        output(x, y) = f(x, y);
    }

    void
    schedule()
    {
        // Provide bounds estimates for autoschedulers (optional but helpful)
        if (using_autoscheduler()) {
            input.set_estimates({ { 0, 1920 }, { 0, 1080 } });
            output.set_estimates({ { 0, 1920 }, { 0, 1080 } });
            return;
        }

        // Manual schedule (used if AUTOSCHEDULER is not enabled)
        const Target t = get_target();

        // Some reasonable defaults
        Var xo{ "xo" }, yo{ "yo" }, xi{ "xi" }, yi{ "yi" };

        // GPU path: works for cuda/opencl/metal targets (if enabled via
        // FEATURES)
        if (t.has_gpu_feature()) {
            // 16x16 tiles as a sane default
            f.gpu_tile(x, y, xo, yo, xi, yi, 16, 16);
            output.compute_root();
        } else {
            // CPU path: tile + vectorize + parallel
            f.compute_root()
                .tile(x, y, xo, yo, xi, yi, 128, 32)
                .vectorize(xi, 16)
                .parallel(yo);
        }

        // Avoid overly conservative bound checks where safe
        output.bound(x, 0, input.dim(0).extent())
            .bound(y, 0, input.dim(1).extent());
    }
};

// Name used by CMake/command line to select this generator.
// If you pass GENERATOR SamplePipeline in CMake, it refers to this string.
HALIDE_REGISTER_GENERATOR(SamplePipeline, samplepipe)