float_to_sample.hpp

#pragma once
 
#include <ossia/dataflow/nodes/media.hpp>
#include <ossia/detail/math.hpp>
 
#include <cstdint>
#include <limits>
 
namespace ossia
{
template <typename SampleFormat, int N>
constexpr SampleFormat float_to_sample(ossia::audio_sample sample) noexcept;
 
template <>
constexpr uint8_t float_to_sample<uint8_t, 8>(ossia::audio_sample sample) noexcept
{
  // 0 -> 255 to -1 -> 1
  if constexpr(std::is_same_v<ossia::audio_sample, float>)
  {
    return (sample + 1.f) * 127.5f;
  }
  else
  {
    return (sample + 1.) * 127.5;
  }
}
 
template <>
constexpr int16_t float_to_sample<int16_t, 16>(ossia::audio_sample sample) noexcept
{
  // TODO division -> multiplication
  if constexpr(std::is_same_v<ossia::audio_sample, float>)
  {
    return sample * (0x7FFF + .5f) - 0.5f;
  }
  else
  {
    return sample * (0x7FFF + .5) - 0.5;
  }
}
 
// ALSA S24_LE: https://stackoverflow.com/a/40301874/1495627
template <>
constexpr int32_t float_to_sample<int32_t, 24>(ossia::audio_sample x) noexcept
{
  if constexpr(std::is_same_v<ossia::audio_sample, float>)
  {
    return (x * (0x7FFFFF + 0.5f)) - 0.5f;
  }
  else
  {
    return (x * (0x7FFFFF + 0.5)) - 0.5;
  }
}
 
template <>
constexpr int32_t float_to_sample<int32_t, 32>(audio_sample x) noexcept
{
  // In double even when the samples are float: 0x7FFFFFFF + 0.5 is not
  // representable as a float and rounds to 2^31, which +1.0 then converts out
  // of int32_t's range.
  return (double(x) * (0x7FFFFFFF + 0.5)) - 0.5;
}
 
template <>
constexpr float float_to_sample<float, 32>(float sample) noexcept
{
  return sample;
}
 
#if defined(_MSC_VER)
#define OSSIA_RESTRICT __restrict
#else
#define OSSIA_RESTRICT __restrict__
#endif
 
template <typename SampleFormat, int N, int ByteIncrement, typename InputFormat>
  requires(sizeof(SampleFormat) == ByteIncrement)
inline void interleave(
    const InputFormat* const* OSSIA_RESTRICT in, SampleFormat* OSSIA_RESTRICT out,
    int channels, int bs)
{
  for(int c = 0; c < channels; c++)
  {
    auto* in_channel = in[c];
    for(int k = 0; k < bs; k++)
    {
      out[k * channels + c] = float_to_sample<SampleFormat, N>(in_channel[k]);
    }
  }
}
 
template <typename SampleFormat, int N, int ByteIncrement, typename InputFormat>
  requires(sizeof(SampleFormat) != ByteIncrement)
inline void interleave(
    const InputFormat* const* OSSIA_RESTRICT in, SampleFormat* out, int channels, int bs)
{
  for(int c = 0; c < channels; c++)
  {
    auto* in_channel = in[c];
    for(int k = 0; k < bs; k++)
    {
      // Case packed 24-bit: we have to go through raw char*
      char* out_raw = reinterpret_cast<char*>(out);
      auto mem
          = reinterpret_cast<SampleFormat*>(out_raw[(k * channels + c) * ByteIncrement]);
      *mem = float_to_sample<SampleFormat, N>(in_channel[k]);
    }
  }
}
 
template <typename SampleFormat, int N, typename InputFormat>
inline void convert(
    const InputFormat* const* OSSIA_RESTRICT in, SampleFormat* OSSIA_RESTRICT out,
    int channels, int bs)
{
  for(int c = 0; c < channels; c++)
  {
    auto* in_channel = in[c];
    auto* out_channel = out + c * bs;
    for(int k = 0; k < bs; k++)
    {
      out_channel[k] = float_to_sample<SampleFormat, N>(in_channel[k]);
    }
  }
}
}