embedded_audio/stream/
sigma_delta_bits.rs

1/// Tier C: packed 1-bit stream (MSB first). Each bit maps to ±127 PCM before duty.
2#[derive(Debug, Clone, Copy)]
3pub struct SigmaDeltaBitStream<'a> {
4    data: &'a [u8],
5    byte_index: usize,
6    bit_mask: u8,
7    looped: bool,
8}
9
10impl<'a> SigmaDeltaBitStream<'a> {
11    pub fn new(data: &'a [u8], effect_flags: u8) -> Self {
12        Self {
13            data,
14            byte_index: 0,
15            bit_mask: 0x80,
16            looped: effect_flags & crate::tier::flags::LOOP != 0,
17        }
18    }
19
20    pub fn reset(&mut self) {
21        self.byte_index = 0;
22        self.bit_mask = 0x80;
23    }
24
25    pub fn is_done(&self) -> bool {
26        !self.looped && self.byte_index >= self.data.len()
27    }
28}
29
30impl<'a> SigmaDeltaBitStream<'a> {
31    pub fn next_sample(&mut self) -> Option<i8> {
32        if self.byte_index >= self.data.len() {
33            if self.looped && !self.data.is_empty() {
34                self.reset();
35            } else {
36                return None;
37            }
38        }
39        let byte = self.data[self.byte_index];
40        let high = (byte & self.bit_mask) != 0;
41        self.bit_mask >>= 1;
42        if self.bit_mask == 0 {
43            self.bit_mask = 0x80;
44            self.byte_index += 1;
45        }
46        Some(if high { 127 } else { -127 })
47    }
48}
embedded_audio/stream/sigma_delta_bits.rs

embedded_audio/stream/
sigma_delta_bits.rs
