From 7ef059fa5bea5f75870b48a3ac9d8316fd8b6baf Mon Sep 17 00:00:00 2001
From: William P <me@williamtpeebles.com>
Date: Tue, 25 Mar 2025 21:49:51 -0400
Subject: [PATCH] play with FSK more

---
 amps-handset-emu/src/audio.rs | 22 +++++++++++++++++----
 amps-handset-emu/src/fsk.rs   | 37 ++++++++++++++++++++++++++++-------
 amps-handset-emu/src/main.rs  | 14 +++++++++----
 3 files changed, 58 insertions(+), 15 deletions(-)

diff --git a/amps-handset-emu/src/audio.rs b/amps-handset-emu/src/audio.rs
index c3bc7a1..7b7c93f 100644
--- a/amps-handset-emu/src/audio.rs
+++ b/amps-handset-emu/src/audio.rs
@@ -1,20 +1,34 @@
-use cpal::{StreamConfig, traits::{DeviceTrait, HostTrait}};
+use cpal::traits::{DeviceTrait, HostTrait, StreamTrait};
+use std::sync::{Arc, Mutex};
 
 pub fn play_audio(signal: &[f32]) -> Result<(), Box<dyn std::error::Error>> {
     let host = cpal::default_host();
-    let device = host.default_output_device()?.config();
+    let device = host.default_output_device().ok_or("No output device found")?;
     let config = device.default_output_config()?.config();
 
+    let signal = Arc::new(Mutex::new(signal.to_vec()));
+    let singal_clone = Arc::clone(&signal);
+    let mut index = 0;
+
     let stream = device.build_output_stream(
         &config,
         move |data: &mut [f32], _: &cpal::OutputCallbackInfo| {
-            data.copy_from_slice(&signal[..data.len()]);
+            let signal = singal_clone.lock().unwrap();
+
+            for sample in data.iter_mut() {
+                *sample = if index < signal.len() {
+                    signal[index]
+                } else {
+                    0.0
+                };
+                index += 1;
+            }
         },
         |err| eprintln!("Error: {:?}", err),
         None
     )?;
 
     stream.play()?;
-    std::thread::sleep(std::time::Duration::from_secs(5));
+    std::thread::sleep(std::time::Duration::from_secs(1));
     Ok(())
 }
\ No newline at end of file
diff --git a/amps-handset-emu/src/fsk.rs b/amps-handset-emu/src/fsk.rs
index 0ca938a..1d72508 100644
--- a/amps-handset-emu/src/fsk.rs
+++ b/amps-handset-emu/src/fsk.rs
@@ -1,20 +1,43 @@
 use std::f32::consts::PI;
-use dasp_signal::Signal;
 
 const SAMPLE_RATE: f32 = 44100.0;
 const BAUD_RATE: f32 = 1200.0;
 const FREQ_MARK: f32 = 1200.0;
 const FREQ_SPACE: f32 = 2200.0;
 
-pub fn fsk_modulate(bits: &[u8]) -> Vec<f32> {
+pub fn fsk_modulate(data: &[u8]) -> Vec<f32> {
     let samples_per_bit = (SAMPLE_RATE / BAUD_RATE) as usize;
     let mut signal = Vec::new();
 
-    for &bit in bits {
-        let freq = if bit == 1 { FREQ_MARK } else { FREQ_SPACE };
-        for i in 0..samples_per_bit {
-            let t = i as f32 / SAMPLE_RATE;
-            signal.push((2.0 * PI * freq * t).sin());
+    for &byte in data {
+        for i in (0..8).rev() {
+            let bit = (byte >> i) & 1;
+            let freq = if bit == 1 { FREQ_MARK } else { FREQ_SPACE };
+
+            for j in 0..samples_per_bit {
+                let t = (signal.len() + j) as f32 / SAMPLE_RATE;
+                signal.push((2.0 * PI * freq * t).sin());
+            }
+        }
+    }
+    signal
+}
+
+pub fn afsk_modulate(data: &[u8], carrier_freq: f32) -> Vec<f32> {
+    let samples_per_bit = (SAMPLE_RATE / BAUD_RATE) as usize;
+    let mut signal = Vec::new();
+
+    for &byte in data {
+        for i in (0..8).rev() {
+            let bit = (byte >> i) & 1;
+            let freq = if bit == 1 { FREQ_MARK } else { FREQ_SPACE };
+
+            for j in 0..samples_per_bit {
+                let t = (signal.len() + j) as f32 / SAMPLE_RATE;
+                let fsk_wave = (2.0 * PI * freq * t).sin();
+                let carrier_wave = (2.0 * PI * carrier_freq * t).sin();
+                signal.push(fsk_wave * carrier_wave); // Modulate FSK onto the carrier
+            }
         }
     }
     signal
diff --git a/amps-handset-emu/src/main.rs b/amps-handset-emu/src/main.rs
index 7579915..f70eb30 100644
--- a/amps-handset-emu/src/main.rs
+++ b/amps-handset-emu/src/main.rs
@@ -1,4 +1,5 @@
-use fsk::fsk_modulate;
+use audio::play_audio;
+use fsk::afsk_modulate;
 use text_io::scan;
 use std::io;
 
@@ -15,9 +16,14 @@ fn main() -> Result<(), io::Error> {
     match a {
         1 => {
             println!("1 has been pressed! No test tone implemented yet");
-            let tone: signal;
-            tone = fsk_modulate([0x25, 0x08, 0x00, 0x25, 0xA0]);
-            play_audio(tone);
+            let tone: Vec<f32>;
+            tone = afsk_modulate(&[
+                0b10101010, 0b01010101, 0b10101010, 0b01010101, 0b10101010, 0b01010101, 0b10101010, 0b01010101, 0b10101010, 0b01010101,
+                0b1000101,0b11111111,0b1000101,0b11111111,0b11111111,0b1000101,0b11111111,0b11111111,0b1000101,0b11111111,0b11111111, 
+                ], 1700.0);
+            let repeated_tone: Vec<f32> = tone.iter().cloned().cycle().take(tone.len() * 10).collect();
+            
+            play_audio(&repeated_tone);
             return main();
         },
         0 => {