From 02c0552df3bbdfc9b2f63c86729c2ca71c8ccf21 Mon Sep 17 00:00:00 2001
From: heck <heck@pep.foundation>
Date: Wed, 6 Sep 2023 19:27:51 +0200
Subject: [PATCH] audio engine:double buffering working nicely now

---
 src/cppmain.cc | 66 ++++++++++++++++++++++++++++++++------------------
 1 file changed, 43 insertions(+), 23 deletions(-)

diff --git a/src/cppmain.cc b/src/cppmain.cc
index 173e37f..90862b9 100644
--- a/src/cppmain.cc
+++ b/src/cppmain.cc
@@ -7,21 +7,23 @@
 #include <bitset>
 #include "limits"
 #include <sstream>
+#include <iomanip>
 
 #define SAMPLE_FREQ 44200
 #define SAMPLE_MAX 4096
-#define BUFFER_SIZE 16
-#define BLOCK_SIZE 8
+#define BUFFER_SIZE 256
+#define BLOCK_SIZE 128
 
 const double pi{ std::acos(-1) };
 
 // Buffer and block
 static u32 audio_buffer[BUFFER_SIZE];
-static u32* block = &audio_buffer[0];
-static volatile bool process_block{ false };
+static u32 *block = &audio_buffer[0];
+static volatile bool process_block{ true };
+static volatile bool process_block2{ true };
 
 // time
-static u64 time{ 0 };
+static u64 inf_phasor{ 0 };
 
 // misc
 static volatile int freq = 100;
@@ -40,7 +42,10 @@ namespace Heck {
     {
         std::string out{ msg };
         out.append("\r\n");
-        CDC_Transmit_FS((uint8_t *)out.data(), out.size());
+        u8 status = CDC_Transmit_FS((uint8_t *)out.data(), out.size());
+        if (status == USBD_BUSY) {
+            // usb buffer overflow
+        }
     }
 
     // LED
@@ -72,8 +77,6 @@ namespace Heck {
         led_green_toggle();
     }
 
-    // dont forget to start the DAC
-    // HAL_DAC_Start(&hdac, DAC_CHANNEL_1);
     void bytebeat()
     {
         long t{ 0 };
@@ -100,7 +103,16 @@ namespace Heck {
         for (int i = 0; i < BUFFER_SIZE; i++) {
             u32 val = random(SAMPLE_MAX);
             audio_buffer[i] = val;
-            log(std::to_string(val));
+        }
+    }
+
+    void block_fill_saw()
+    {
+        u32 *b = block;
+        u32 step = (SAMPLE_MAX - (SAMPLE_MAX / 4)) / BLOCK_SIZE;
+        for (int i = 0; i < BLOCK_SIZE; i++) {
+            u32 val = i * step;
+            b[i] = val;
         }
     }
 
@@ -111,7 +123,6 @@ namespace Heck {
             float p = float(i) / (float)BUFFER_SIZE - 0.5;
             u32 val = sin(p) * SAMPLE_MAX;
             audio_buffer[i] = val;
-            log(std::to_string(val));
         }
     }
 
@@ -121,7 +132,6 @@ namespace Heck {
         for (int i = 0; i < BUFFER_SIZE; i++) {
             u32 val = audio_buffer[i] / div;
             audio_buffer[i] = val;
-            log(std::to_string(val));
         }
     }
 
@@ -131,7 +141,6 @@ namespace Heck {
         u32 buf_index = random(BUFFER_SIZE);
         u32 buf_val = random(max);
         audio_buffer[buf_index] = buf_val;
-        log("i:" + std::to_string(buf_index) + " v:" + std::to_string(buf_val));
     }
 
     std::string reg_to_string(uint32_t val)
@@ -152,31 +161,43 @@ namespace Heck {
 
     void calculate_audio()
     {
-//        log("calculate_audio time: ");
-        u64 t = time;
+        //        log("calculate_audio time: ");
+        u32 *b = block;
+        u64 t = inf_phasor;
         u32 samps = hz_to_samps(freq);
-
+        u32 val{ 0 };
         for (int i = 0; i < BLOCK_SIZE; i++) {
-            block[i] = t % samps;
+            val = t % samps;
+            b[i] = val * 8;
             t++;
         }
     }
 
+    std::string block_to_string()
+    {
+        u32 *b = block;
+        std::stringstream ss{};
+        for (int i = 0; i < BLOCK_SIZE; i++) {
+            ss << std::setw(4) << b[i] << "  ";
+        }
+        return ss.str();
+    }
+
     void main()
     {
         heck_debug_suspend();
         log("Starting...");
 
         HAL_TIM_Base_Start_IT(&htim_blinky_led);
-        HAL_DAC_Start_DMA(&hdac1, DAC_CHANNEL_1, (u32 *)audio_buffer, BUFFER_SIZE, DAC_ALIGN_12B_R);
+        HAL_DAC_Start_DMA(&hdac1, DAC_CHANNEL_1, audio_buffer, BUFFER_SIZE, DAC_ALIGN_12B_R);
         HAL_TIM_Base_Start_IT(&htim_dac1);
 
         log("Entering MainLoop...");
         while (true) {
             if (process_block) {
-                calculate_audio();
-                time += BLOCK_SIZE;
                 process_block = false;
+                calculate_audio();
+                inf_phasor += BLOCK_SIZE;
             }
         }
     }
@@ -209,7 +230,6 @@ extern "C" void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
         //        Heck::log(
         //            "TIM2 timer: instance: " + std::to_string(reinterpret_cast<u32>(htim->Instance)) +
         //            " channel: " + std::to_string(htim->Channel));
-        //        Heck::log(std::to_string(time));
     } else if (htim->Instance == TIM3) {
         Heck::log(
             "TIM3 timer: instance: " + std::to_string(reinterpret_cast<u32>(htim->Instance)) +
@@ -225,15 +245,15 @@ extern "C" void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
 
 extern "C" void HAL_DAC_ConvHalfCpltCallbackCh1(DAC_HandleTypeDef *hdac)
 {
-    Heck::log("HAL_DAC_ConvHalfCpltCallbackCh1");
+    //    Heck::log("HAL_DAC_ConvHalfCpltCallbackCh1");
     block = &audio_buffer[0];
     process_block = true;
 }
 
 extern "C" void HAL_DAC_ConvCpltCallbackCh1(DAC_HandleTypeDef *hdac)
 {
-    Heck::log("HAL_DAC_ConvCpltCallbackCh1");
-    block = &audio_buffer[BUFFER_SIZE];
+    //    Heck::log("HAL_DAC_ConvCpltCallbackCh1");
+    block = &audio_buffer[BLOCK_SIZE];
     process_block = true;
 }