Program Listing for File WaveformWebpHighway-inl.h

↰ Return to documentation for file (include\util\function\image\WaveformWebpHighway-inl.h)

#include <algorithm>
#include <cstddef>

#undef HWY_TARGET_INCLUDE
#define HWY_TARGET_INCLUDE "WaveformWebpHighway-inl.h"
#include "hwy/foreach_target.h"

#include <hwy/highway.h>

namespace HWY_NAMESPACE {

HWY_ATTR
void
ComputeWaveformColumnExtremaSIMD(const float *samples,
                                 std::size_t  pcm_per_pixel,
                                 std::size_t  x_pixels,
                                 float       *mins_out,
                                 float       *maxs_out)
{
    const hwy::HWY_NAMESPACE::ScalableTag<float> tag;
    const std::size_t                            lane_count =
        hwy::HWY_NAMESPACE::Lanes(tag);
    const auto neg_one = hwy::HWY_NAMESPACE::Set(tag, -1.0f);
    const auto pos_one = hwy::HWY_NAMESPACE::Set(tag, 1.0f);

    for (std::size_t x = 0; x < x_pixels; ++x) {
        const float *column = samples + (x * pcm_per_pixel);
        auto         min_v  = pos_one;
        auto         max_v  = neg_one;
        std::size_t  i      = 0;

        for (; i + lane_count <= pcm_per_pixel; i += lane_count) {
            auto values = hwy::HWY_NAMESPACE::LoadU(tag, column + i);
            values      = hwy::HWY_NAMESPACE::Min(
                hwy::HWY_NAMESPACE::Max(values, neg_one),
                pos_one);
            min_v = hwy::HWY_NAMESPACE::Min(min_v, values);
            max_v = hwy::HWY_NAMESPACE::Max(max_v, values);
        }

        float min_sample = hwy::HWY_NAMESPACE::ReduceMin(tag, min_v);
        float max_sample = hwy::HWY_NAMESPACE::ReduceMax(tag, max_v);

        for (; i < pcm_per_pixel; ++i) {
            const float sample = std::clamp(column[i], -1.0f, 1.0f);
            min_sample         = std::min(min_sample, sample);
            max_sample         = std::max(max_sample, sample);
        }

        mins_out[x] = min_sample;
        maxs_out[x] = max_sample;
    }
}

} // namespace HWY_NAMESPACE