Added Audio Out to Soundboard app (#1748)

firmware/baseband/audio_dma.cpp

@@ -123,10 +123,10 @@ constexpr gpdma::channel::Config config_rx() {
 /* TODO: Clean up terminology around "buffer", "transfer", "samples" */
 
 constexpr size_t buffer_samples_log2n = 7;
-constexpr size_t buffer_samples = (1 << buffer_samples_log2n);
+constexpr size_t buffer_samples = (1 << buffer_samples_log2n);  // 2^7 = 128 byte circular DMA buffer
 constexpr size_t transfers_per_buffer_log2n = 2;
-constexpr size_t transfers_per_buffer = (1 << transfers_per_buffer_log2n);
-constexpr size_t transfer_samples = buffer_samples / transfers_per_buffer;
+constexpr size_t transfers_per_buffer = (1 << transfers_per_buffer_log2n);  // 2^2 = 4 transfer buffers in the circular buffer
+constexpr size_t transfer_samples = buffer_samples / transfers_per_buffer;  // 128/4 = 32 samples in each transfer buffer
 constexpr size_t transfers_mask = transfers_per_buffer - 1;
 
 constexpr size_t buffer_bytes = buffer_samples * sizeof(sample_t);
@@ -144,6 +144,8 @@ static constexpr auto& gpdma_channel_i2s0_rx = gpdma::channels[portapack::i2s0_r
 static volatile const gpdma::channel::LLI* tx_next_lli = nullptr;
 static volatile const gpdma::channel::LLI* rx_next_lli = nullptr;
 
+static bool single_tx_buffer = false;
+
 static void tx_transfer_complete() {
     tx_next_lli = gpdma_channel_i2s0_tx.next_lli();
 }
@@ -213,11 +215,16 @@ void disable() {
     gpdma_channel_i2s0_rx.disable();
 }
 
+void shrink_tx_buffer() {
+    single_tx_buffer = true;
+    lli_tx_loop[0].lli = lli_pointer(&lli_tx_loop[0]);
+}
+
 buffer_t tx_empty_buffer() {
     const auto next_lli = tx_next_lli;
     if (next_lli) {
         const size_t next_index = next_lli - &lli_tx_loop[0];
-        const size_t free_index = (next_index + transfers_per_buffer - 2) & transfers_mask;
+        const size_t free_index = (single_tx_buffer) ? 0 : (next_index + transfers_per_buffer - 2) & transfers_mask;
         return {reinterpret_cast<sample_t*>(lli_tx_loop[free_index].srcaddr), transfer_samples};
     } else {
         return {nullptr, 0};

firmware/baseband/audio_dma.hpp

@@ -47,6 +47,7 @@ void init();
 void configure();
 void enable();
 void disable();
+void shrink_tx_buffer();
 
 audio::buffer_t tx_empty_buffer();
 audio::buffer_t rx_empty_buffer();

firmware/baseband/proc_audiotx.cpp

@@ -41,6 +41,12 @@ void AudioTXProcessor::execute(const buffer_c8_t& buffer) {
             }
         }
 
+        // Output to speaker too
+        uint32_t imod32 = i & (AUDIO_OUTPUT_BUFFER_SIZE - 1);
+        audio_data[imod32] = ((int16_t)audio_sample - 0x80) * (1.0f / 128.0f);
+        if (imod32 == (AUDIO_OUTPUT_BUFFER_SIZE - 1))
+            audio_output.write(audio_buffer);
+
         sample = tone_gen.process(audio_sample - 0x80);
 
         // FM
@@ -95,6 +101,8 @@ void AudioTXProcessor::audio_config(const AudioTXConfigMessage& message) {
     tone_gen.configure(message.tone_key_delta, message.tone_key_mix_weight);
     progress_interval_samples = message.divider;
     resample_acc = 0;
+    audio_output.configure(false);
+    audio::dma::shrink_tx_buffer();
 }
 
 void AudioTXProcessor::replay_config(const ReplayConfigMessage& message) {

firmware/baseband/proc_audiotx.hpp

@@ -27,6 +27,10 @@
 #include "baseband_thread.hpp"
 #include "tone_gen.hpp"
 #include "stream_output.hpp"
+#include "audio_output.hpp"
+#include "audio_dma.hpp"
+
+#define AUDIO_OUTPUT_BUFFER_SIZE 32
 
 class AudioTXProcessor : public BasebandProcessor {
    public:
@@ -48,6 +52,10 @@ class AudioTXProcessor : public BasebandProcessor {
     int32_t sample{0}, delta{};
     int8_t re{0}, im{0};
 
+    float audio_data[AUDIO_OUTPUT_BUFFER_SIZE];
+    buffer_f32_t audio_buffer{audio_data, AUDIO_OUTPUT_BUFFER_SIZE, 48000};
+    AudioOutput audio_output{};
+
     size_t progress_interval_samples = 0, progress_samples = 0;
 
     bool configured{false};