mpd/src/pcm/Traits.hxx
2023-03-06 18:44:20 +01:00

159 lines
4.0 KiB
C++

// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright The Music Player Daemon Project
#pragma once
#include "SampleFormat.hxx"
#include <cstddef>
#include <cstdint>
/**
* This template describes the specified #SampleFormat. This is an
* empty prototype; the specializations contain the real definitions.
* See SampleTraits<uint8_t> for more documentation.
*/
template<SampleFormat F>
struct SampleTraits {};
template<>
struct SampleTraits<SampleFormat::S8> {
/**
* The type used for one sample value.
*/
typedef int8_t value_type;
/**
* A writable pointer.
*/
typedef value_type *pointer;
/**
* A read-only pointer.
*/
typedef const value_type *const_pointer;
/**
* A "long" type that is large and accurate enough for adding
* two values without risking an (integer) overflow or
* (floating point) precision loss.
*/
typedef int sum_type;
/**
* A "long" type that is large and accurate enough for
* arithmetic without risking an (integer) overflow or
* (floating point) precision loss.
*/
typedef int_least32_t long_type;
/**
* The size of one sample in bytes.
*/
static constexpr size_t SAMPLE_SIZE = sizeof(value_type);
/**
* The integer bit depth of one sample. This attribute may
* not exist if this is not an integer sample format.
*/
static constexpr unsigned BITS = sizeof(value_type) * 8;
/**
* The minimum sample value.
*/
static constexpr value_type MIN = -(sum_type(1) << (BITS - 1));
/**
* The maximum sample value.
*/
static constexpr value_type MAX = (sum_type(1) << (BITS - 1)) - 1;
/**
* A value which represents "silence".
*/
static constexpr value_type SILENCE = 0;
};
template<>
struct SampleTraits<SampleFormat::S16> {
typedef int16_t value_type;
typedef value_type *pointer;
typedef const value_type *const_pointer;
typedef int_least32_t sum_type;
typedef int_least32_t long_type;
static constexpr size_t SAMPLE_SIZE = sizeof(value_type);
static constexpr unsigned BITS = sizeof(value_type) * 8;
static constexpr value_type MIN = -(sum_type(1) << (BITS - 1));
static constexpr value_type MAX = (sum_type(1) << (BITS - 1)) - 1;
static constexpr value_type SILENCE = 0;
};
template<>
struct SampleTraits<SampleFormat::S32> {
typedef int32_t value_type;
typedef value_type *pointer;
typedef const value_type *const_pointer;
typedef int_least64_t sum_type;
typedef int_least64_t long_type;
static constexpr size_t SAMPLE_SIZE = sizeof(value_type);
static constexpr unsigned BITS = sizeof(value_type) * 8;
static constexpr value_type MIN = -(sum_type(1) << (BITS - 1));
static constexpr value_type MAX = (sum_type(1) << (BITS - 1)) - 1;
static constexpr value_type SILENCE = 0;
};
template<>
struct SampleTraits<SampleFormat::S24_P32> {
typedef int32_t value_type;
typedef value_type *pointer;
typedef const value_type *const_pointer;
typedef int_least32_t sum_type;
typedef int_least64_t long_type;
static constexpr size_t SAMPLE_SIZE = sizeof(value_type);
static constexpr unsigned BITS = 24;
static constexpr value_type MIN = -(sum_type(1) << (BITS - 1));
static constexpr value_type MAX = (sum_type(1) << (BITS - 1)) - 1;
static constexpr value_type SILENCE = 0;
};
template<>
struct SampleTraits<SampleFormat::FLOAT> {
typedef float value_type;
typedef value_type *pointer;
typedef const value_type *const_pointer;
typedef float sum_type;
typedef float long_type;
static constexpr size_t SAMPLE_SIZE = sizeof(value_type);
static constexpr value_type MIN = -1;
static constexpr value_type MAX = 1;
static constexpr value_type SILENCE = 0;
};
template<>
struct SampleTraits<SampleFormat::DSD> {
typedef std::byte value_type;
typedef value_type *pointer;
typedef const value_type *const_pointer;
static constexpr size_t SAMPLE_SIZE = sizeof(value_type);
/* 0x69 = 01101001
* This pattern "on repeat" makes a low energy 352.8 kHz tone
* and a high energy 1.0584 MHz tone which should be filtered
* out completely by any playback system --> silence
*/
static constexpr value_type SILENCE{0x69};
};