melpe-rs 0.1.2

MELPe vocoder (STANAG 4591) in pure Rust — 600 bps voice codec, no_std compatible
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
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294

/// Math shim for no_std compatibility
///
/// Under `std` (default): calls native f32 methods (hardware-backed on x86_64)
/// Under `embedded`: calls libm pure-Rust implementations (works on Xtensa, etc.)
///
/// All functions take and return f32. Function names follow libm convention
/// (sinf, cosf, etc.) to make call sites explicit about the shim.

/// Sine
#[inline(always)]
pub fn sinf(x: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { x.sin() }
    #[cfg(feature = "embedded")]
    { libm::sinf(x) }
}

/// Cosine
#[inline(always)]
pub fn cosf(x: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { x.cos() }
    #[cfg(feature = "embedded")]
    { libm::cosf(x) }
}

/// Arc cosine
#[inline(always)]
pub fn acosf(x: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { x.acos() }
    #[cfg(feature = "embedded")]
    { libm::acosf(x) }
}

/// Hyperbolic sine
#[inline(always)]
pub fn sinhf(x: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { x.sinh() }
    #[cfg(feature = "embedded")]
    { libm::sinhf(x) }
}

/// Square root
#[inline(always)]
pub fn sqrtf(x: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { x.sqrt() }
    #[cfg(feature = "embedded")]
    { libm::sqrtf(x) }
}

/// Natural logarithm
#[inline(always)]
pub fn logf(x: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { x.ln() }
    #[cfg(feature = "embedded")]
    { libm::logf(x) }
}

/// Exponential (e^x)
#[inline(always)]
pub fn expf(x: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { x.exp() }
    #[cfg(feature = "embedded")]
    { libm::expf(x) }
}

/// Base-10 logarithm
#[inline(always)]
pub fn log10f(x: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { x.log10() }
    #[cfg(feature = "embedded")]
    { libm::log10f(x) }
}

/// Power: base^exp
#[inline(always)]
pub fn powf(base: f32, exp: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { base.powf(exp) }
    #[cfg(feature = "embedded")]
    { libm::powf(base, exp) }
}

/// Round to nearest integer
#[inline(always)]
pub fn roundf(x: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { x.round() }
    #[cfg(feature = "embedded")]
    { libm::roundf(x) }
}

/// Absolute value
#[inline(always)]
pub fn fabsf(x: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { x.abs() }
    #[cfg(feature = "embedded")]
    { libm::fabsf(x) }
}

/// Maximum of two floats
#[inline(always)]
pub fn fmaxf(a: f32, b: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { a.max(b) }
    #[cfg(feature = "embedded")]
    { libm::fmaxf(a, b) }
}

/// Minimum of two floats
#[inline(always)]
pub fn fminf(a: f32, b: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { a.min(b) }
    #[cfg(feature = "embedded")]
    { libm::fminf(a, b) }
}

/// Clamp a float to [lo, hi]
#[inline(always)]
pub fn clampf(x: f32, lo: f32, hi: f32) -> f32 {
    fmaxf(lo, fminf(x, hi))
}

/// Floor (truncate towards negative infinity)
#[inline(always)]
pub fn floorf(x: f32) -> f32 {
    #[cfg(not(feature = "embedded"))]
    { x.floor() }
    #[cfg(feature = "embedded")]
    { libm::floorf(x) }
}

/// Check if finite (not NaN or infinity) — works in core via to_bits
#[inline(always)]
pub fn is_finite(x: f32) -> bool {
    // Exponent bits mask for f32: bits 23..30
    // Finite if exponent is not all 1s
    let bits = x.to_bits();
    (bits & 0x7F80_0000) != 0x7F80_0000
}

/// Simple insertion sort for small f32 slices (no_std friendly).
/// Used in place of `[f32]::sort_by` which requires alloc.
pub fn sort_f32(slice: &mut [f32]) {
    let n = slice.len();
    for i in 1..n {
        let key = slice[i];
        let mut j = i;
        while j > 0 && slice[j - 1] > key {
            slice[j] = slice[j - 1];
            j -= 1;
        }
        slice[j] = key;
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use core::f32::consts::PI;

    const TOL: f32 = 1e-5;

    #[test]
    fn test_sinf() {
        assert!(sinf(0.0).abs() < TOL);
        assert!((sinf(PI / 2.0) - 1.0).abs() < TOL);
        assert!((sinf(PI) - 0.0).abs() < TOL);
    }

    #[test]
    fn test_cosf() {
        assert!((cosf(0.0) - 1.0).abs() < TOL);
        assert!(cosf(PI / 2.0).abs() < TOL);
        assert!((cosf(PI) - (-1.0)).abs() < TOL);
    }

    #[test]
    fn test_acosf() {
        assert!(acosf(1.0).abs() < TOL);
        assert!((acosf(0.0) - PI / 2.0).abs() < TOL);
        assert!((acosf(-1.0) - PI).abs() < TOL);
    }

    #[test]
    fn test_sinhf() {
        assert!(sinhf(0.0).abs() < TOL);
        assert!((sinhf(1.0) - 1.17520).abs() < 0.001);
    }

    #[test]
    fn test_sqrtf() {
        assert!((sqrtf(4.0) - 2.0).abs() < TOL);
        assert!((sqrtf(9.0) - 3.0).abs() < TOL);
        assert!(sqrtf(0.0).abs() < TOL);
    }

    #[test]
    fn test_logf() {
        assert!(logf(1.0).abs() < TOL);
        assert!((logf(core::f32::consts::E) - 1.0).abs() < TOL);
    }

    #[test]
    fn test_expf() {
        assert!((expf(0.0) - 1.0).abs() < TOL);
        assert!((expf(1.0) - core::f32::consts::E).abs() < 0.001);
    }

    #[test]
    fn test_log10f() {
        assert!(log10f(1.0).abs() < TOL);
        assert!((log10f(10.0) - 1.0).abs() < TOL);
        assert!((log10f(100.0) - 2.0).abs() < TOL);
    }

    #[test]
    fn test_powf() {
        assert!((powf(2.0, 3.0) - 8.0).abs() < TOL);
        assert!((powf(10.0, 0.0) - 1.0).abs() < TOL);
        assert!((powf(10.0, -1.0) - 0.1).abs() < 0.001);
    }

    #[test]
    fn test_roundf() {
        assert!((roundf(1.4) - 1.0).abs() < TOL);
        assert!((roundf(1.5) - 2.0).abs() < TOL);
        assert!((roundf(-0.6) - (-1.0)).abs() < TOL);
    }

    #[test]
    fn test_fabsf() {
        assert!((fabsf(-3.0) - 3.0).abs() < TOL);
        assert!((fabsf(3.0) - 3.0).abs() < TOL);
        assert!(fabsf(0.0) < TOL);
    }

    #[test]
    fn test_fmaxf() {
        assert!((fmaxf(1.0, 2.0) - 2.0).abs() < TOL);
        assert!((fmaxf(-1.0, -2.0) - (-1.0)).abs() < TOL);
    }

    #[test]
    fn test_fminf() {
        assert!((fminf(1.0, 2.0) - 1.0).abs() < TOL);
        assert!((fminf(-1.0, -2.0) - (-2.0)).abs() < TOL);
    }

    #[test]
    fn test_clampf() {
        assert!((clampf(0.5, 0.0, 1.0) - 0.5).abs() < TOL);
        assert!((clampf(-1.0, 0.0, 1.0) - 0.0).abs() < TOL);
        assert!((clampf(2.0, 0.0, 1.0) - 1.0).abs() < TOL);
    }

    #[test]
    fn test_is_finite() {
        assert!(is_finite(0.0));
        assert!(is_finite(1.0));
        assert!(is_finite(-1e30));
        assert!(!is_finite(f32::INFINITY));
        assert!(!is_finite(f32::NEG_INFINITY));
        assert!(!is_finite(f32::NAN));
    }

    #[test]
    fn test_sort_f32() {
        let mut a = [3.0, 1.0, 4.0, 1.5, 2.0];
        sort_f32(&mut a);
        assert!((a[0] - 1.0).abs() < TOL);
        assert!((a[1] - 1.5).abs() < TOL);
        assert!((a[2] - 2.0).abs() < TOL);
        assert!((a[3] - 3.0).abs() < TOL);
        assert!((a[4] - 4.0).abs() < TOL);

        // Already sorted
        sort_f32(&mut a);
        assert!((a[0] - 1.0).abs() < TOL);

        // Single element
        let mut b = [42.0];
        sort_f32(&mut b);
        assert!((b[0] - 42.0).abs() < TOL);
    }
}