.gitignore

@@ -1 +0,0 @@
-/target

Cargo.lock

@@ -1,7 +0,0 @@
-# This file is automatically @generated by Cargo.
-# It is not intended for manual editing.
-version = 4
-
-[[package]]
-name = "adpcm-pwm-dac"
-version = "0.1.0"

Cargo.toml

@@ -1,6 +0,0 @@
-[package]
-name = "adpcm-pwm-dac"
-version = "0.1.0"
-edition = "2024"
-
-[dependencies]

README.md

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+This branch is used by entomologist to track issues.

e4c811653781e69e40b63fd27a8c1e20/description

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+fix scaling on DpcmDecoder::output_next()
+
+currently it scales to u8, but pwm outputs can use more! use usize!

notes.md

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-# ADPCM CODEC
-ref: 1, 2
-
-
-# RESOURCES
-1. [wikipedia: adpcm](https://en.wikipedia.org/wiki/Adaptive_differential_pulse-code_modulation)
-2. [st-micro: an3413](https://www.st.com/resource/en/application_note/an3143-audio-software-codec-for-the-stm8s-stmicroelectronics.pdf)
-3. [st-micro: an4453](file:///home/lex/Downloads/an4453-implementing-the-adpcm-algorithm-in-stm32l1xx-microcontrollers-stmicroelectronics.pdf)

src/dac.rs

@@ -1,221 +0,0 @@
-use crate::interface::DacInterface;
-
-pub enum Direction {
-    Up,
-    Down,
-}
-
-pub struct DpcmSample {
-    direction: Direction,
-    // only 3 bits
-    step_count: u8,
-}
-
-impl DpcmSample {
-    pub fn new(byte: u8, sub_index: usize) -> Self {
-        let data = if sub_index == 0 {
-            byte & 0x0F
-        } else {
-            byte >> 4
-        };
-        let direction = match data & 0x1 {
-            0x1 => Direction::Up,
-            0x0 => Direction::Down,
-            _ => Direction::Up,
-        };
-        let step_count = data >> 1;
-
-        Self {
-            direction,
-            step_count,
-        }
-    }
-}
-
-pub struct Dac<'a, T: DacInterface> {
-    output: T,
-    data: Option<&'a [u8]>,
-    index: usize,
-}
-
-impl<'a, T: DacInterface> Dac<'a, T> {
-    pub fn new(output: T) -> Self {
-        Self {
-            output,
-            data: None,
-            index: 0,
-        }
-    }
-    pub fn load_data(&mut self, data: &'a [u8]) {
-        self.data = Some(data);
-    }
-    pub fn seek_to_sample(&mut self, index: usize) {
-        self.index = index;
-    }
-    pub fn output_next(&mut self) {
-        if let Some(data) = self.data {
-            self.index = self.index + 1;
-            // reset the index to 0 if we roll over
-            if (self.index >= data.len()) {
-                self.index = 0;
-            }
-            self.output.write_amplitude(data[self.index]);
-            // self.output.write_amplitude(100);
-        }
-    }
-}
-
-pub struct DpcmDac<'a, T: DacInterface> {
-    output: T,
-    data: Option<&'a [u8]>,
-    index: usize,
-    prev_amplitude: usize,
-    step_size: usize,
-    min: usize,
-    max: usize,
-}
-
-impl<'a, T: DacInterface> DpcmDac<'a, T> {
-    pub fn new(output: T) -> Self {
-        Self {
-            output,
-            data: None,
-            index: 0,
-            prev_amplitude: 0x80,
-            step_size: 0x3,
-            min: 0x25,
-            max: 0xc8,
-        }
-    }
-    pub fn load_data(&mut self, data: &'a [u8]) {
-        self.data = Some(data);
-    }
-    pub fn seek_to_sample(&mut self, index: usize) {
-        self.index = index;
-    }
-
-    // output the next sampe. returns true if there are samples remaining, false if there are no samples remaining.
-    pub fn output_next(&mut self) -> bool {
-        if let Some(data) = self.data {
-            let sub_index = 1 - self.index % 2;
-
-            let sample = DpcmSample::new(data[self.index / 2], sub_index);
-            let new_amplitude = match sample.direction {
-                Direction::Down => self
-                    .prev_amplitude
-                    .saturating_sub(sample.step_count as usize * self.step_size)
-                    .max(self.min),
-                Direction::Up => (self.prev_amplitude
-                    + (sample.step_count as usize * self.step_size))
-                    .min(self.max),
-            };
-
-            // calculate normalized amplitude and write out
-            let normalized_amplitude = (new_amplitude - self.min) * 100 / (self.max - self.min);
-            self.output.write_amplitude(normalized_amplitude as u8);
-            self.prev_amplitude = new_amplitude;
-
-            // increment the sample index
-            let mut samples_remaining = true;
-            self.index = self.index + 1;
-
-            // reset the index to 0 if we roll over
-            if (self.index >= data.len() * 2) {
-                self.index = 0;
-                self.prev_amplitude = 0x74;
-                samples_remaining = false;
-            }
-
-            // return whether or not we have samples remaining
-            samples_remaining
-        } else {
-            // if the sample failed to load, we (duh) have no more samples remaining
-            false
-        }
-    }
-
-    pub fn disable_output(&mut self) {
-        self.output.disable();
-    }
-}
-
-pub struct DpcmDecoder<'a> {
-    data: Option<&'a [u8]>,
-    index: usize,
-    prev_amplitude: usize,
-    step_size: usize,
-    min: usize,
-    max: usize,
-}
-
-impl<'a> DpcmDecoder<'a> {
-    pub fn new() -> Self {
-        Self {
-            data: None,
-            index: 0,
-            prev_amplitude: 0x0,
-            step_size: 0x3,
-            min: 0x50,
-            max: 0xaa,
-        }
-    }
-    pub fn load_data(&mut self, data: &'a [u8]) {
-        self.data = Some(data);
-    }
-    pub fn seek_to_sample(&mut self, index: usize) {
-        self.index = index;
-    }
-
-    pub fn is_done(&self) -> bool {
-        if let Some(data) = self.data {
-            self.index >= (data.len() * 2) - 1
-        } else {
-            false
-        }
-    }
-
-    // output the next sample's amplitude
-    pub fn output_next(&mut self) -> usize {
-        if let Some(data) = self.data {
-            if self.index >= (data.len() * 2) - 10 {
-                return 0;
-            }
-
-            let sub_index = 1 - self.index % 2;
-
-            let sample = DpcmSample::new(data[self.index / 2], sub_index);
-            let new_amplitude = match sample.direction {
-                Direction::Down => self
-                    .prev_amplitude
-                    .saturating_sub(sample.step_count as usize * self.step_size)
-                    .max(self.min),
-                Direction::Up => (self.prev_amplitude
-                    + (sample.step_count as usize * self.step_size))
-                    .min(self.max),
-            };
-
-            // calculate normalized amplitude
-            // TODO: e4c811653781e69e40b63fd27a8c1e20
-            let normalized_amplitude =
-                (new_amplitude.saturating_sub(self.min)) * 100 / (self.max - self.min);
-            self.prev_amplitude = new_amplitude;
-
-            // increment the sample index
-            let mut samples_remaining = true;
-            self.index = self.index + 1;
-
-            // reset the index to 0 if we roll over
-            // if (self.index >= data.len()  * 2) {
-            //     self.index = 0;
-            //     self.prev_amplitude = 0x74;
-            //     samples_remaining = false;
-            // }
-
-            // return the normalized amplitude
-            return normalized_amplitude;
-        } else {
-            // otherwise just output 0
-            0
-        }
-    }
-}

src/interface.rs

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-pub trait DacInterface {
-    // write the amplitude (0->100%)
-    fn disable(&mut self);
-    fn write_amplitude(&mut self, amplitude: u8);
-}

src/lib.rs

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-#![no_std]
-pub mod interface;
-pub mod dac;