ptcrab 0.1.0

A pure-Rust alternative to the official pxtone library.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158

use super::PtvError;
use crate::data::{FromRead, FromReadVar, WriteTo, WriteVarTo};

use std::io::{Read, Seek, Write};

//--------------------------------------------------------------------------------------------------

/// Ptvoice waveform composed of either coordinate points or sine-wave harmonics.
#[derive(Clone, Debug, PartialEq)]
pub enum PtvWave {
    Coordinate {
        /// Points `(x, y)` that make up the waveform.
        ///
        /// **Points should be ordered by increasing x-coordinate.** Unsorted points can cause
        /// bizarre behaviour in pxtone.
        ///
        /// The official ptvoice editor will refuse to open waveforms with more than 31 points,
        /// though pxtone seems to be able to handle as many as 254 points.
        points: Box<[(u8, i8)]>,
        /// x-width of the waveform. Usually 256.
        x_width: i32,
    },
    Oscillator {
        /// Harmonic numbers and corresponding amplitudes that make up the waveform.
        ///
        /// Harmonic number 0 is always silent, and negative harmonic numbers will crash pxtone.
        harmonics: Box<[(i32, i32)]>,
    },
}

impl PtvWave {
    const COORDINATE: i32 = 0;
    const OSCILLATOR: i32 = 1;

    /// Creates a coordinate waveform from the given points `(x, y)` using the default x-width of
    /// 256.
    ///
    /// **Points should be ordered by increasing x-coordinate.** Unsorted points can cause bizarre
    /// behaviour in pxtone.
    ///
    /// The official ptvoice editor will refuse to open waveforms with more than 31 points, though
    /// pxtone seems to be able to handle as many as 254 points.
    pub fn coordinate_from_points(points: Box<[(u8, i8)]>) -> Self {
        Self::Coordinate {
            points,
            x_width: 256,
        }
    }
    /// Creates a coordinate waveform from a function f(x) = y over x = [0, 1) with the given number
    /// of points.
    ///
    /// The official ptvoice editor will refuse to open waveforms with more than 31 points, though
    /// pxtone seems to be able to handle as many as 254 points.
    pub fn coordinate_from_function(point_count: u8, y_function: impl Fn(f32) -> f32) -> Self {
        Self::coordinate_from_points(
            (0..point_count)
                .map(|i| {
                    let x = i as f32 / point_count as f32;

                    ((256. * x) as u8, (127. * y_function(x)) as i8)
                })
                .collect(),
        )
    }

    /// Creates an oscillator waveform from the given `(harmonic_num, amplitude)` pairs.
    ///
    /// Harmonic number 0 is always silent, and negative harmonic numbers will crash pxtone.
    pub fn oscillator_from_pairs(harmonics: Box<[(i32, i32)]>) -> Self {
        Self::Oscillator { harmonics }
    }
}

impl FromRead<Self> for PtvWave {
    type Error = PtvError;

    fn from_read<R: Read>(source: &mut R) -> Result<Self, Self::Error> {
        // Read & match wave type.
        match i32::from_read_var(source)? {
            Self::COORDINATE => {
                let point_count: usize = i32::from_read_var(source)?
                    .try_into()
                    .map_err(|_| PtvError::Invalid)?;
                let x_width = i32::from_read_var(source)?;

                // Read `(x, y)` pairs.
                let points = (0..point_count)
                    .map(|_| <(u8, i8)>::from_read(source))
                    .collect::<Result<Box<[_]>, _>>()?;

                Ok(PtvWave::Coordinate { points, x_width })
            }

            Self::OSCILLATOR => {
                let harmonic_count: usize = i32::from_read_var(source)?
                    .try_into()
                    .map_err(|_| PtvError::Invalid)?;

                // Read `(harmonic_num, amplitude)` pairs.
                let harmonics = (0..harmonic_count)
                    .map(|_| <(i32, i32)>::from_read_var(source))
                    .collect::<Result<Box<[_]>, _>>()?;

                Ok(Self::Oscillator { harmonics })
            }

            // Unknown wave type.
            _ => Err(PtvError::Invalid),
        }
    }
}

impl WriteTo for PtvWave {
    type Error = PtvError;

    fn write_to<W: Write + Seek>(&self, sink: &mut W) -> Result<u64, Self::Error> {
        match &self {
            Self::Coordinate { points, x_width } => {
                let start_pos = Self::COORDINATE.write_var_to(sink)?;

                i32::try_from(points.len())
                    .map_err(|_| PtvError::Oversized)?
                    .write_var_to(sink)?;
                x_width.write_var_to(sink)?;

                // Write `(x, y)` pairs.
                for (x, y) in points.iter() {
                    x.write_to(sink)?;
                    y.write_to(sink)?;
                }

                Ok(start_pos)
            }

            Self::Oscillator { harmonics } => {
                let start_pos = Self::OSCILLATOR.write_var_to(sink)?;

                i32::try_from(harmonics.len())
                    .map_err(|_| PtvError::Oversized)?
                    .write_var_to(sink)?;

                // Write `(harmonic_num, amplitude)` pairs.
                for (harmonic_num, amplitude) in harmonics.iter() {
                    harmonic_num.write_var_to(sink)?;
                    amplitude.write_var_to(sink)?;
                }

                Ok(start_pos)
            }
        }
    }
}

impl Default for PtvWave {
    fn default() -> Self {
        Self::coordinate_from_points(Box::new([(0, 0)]))
    }
}