freertos task test sdcard->i2s buffer

src/main.cpp

@@ -10,15 +10,56 @@
 #include "keyboard.h"
 #include "sdcard.h"
 #include "sound.h"
+#include "ringbuf.h"
 
 #define VERSION "0.0"
 #define LED_PIN 21
+#define BUF_LENGTH 1024
 
 Keyboard keyboard;
 SDCard sdcard;
 Sound sound;
+Ringbuf ringbuf = Ringbuf((size_t) BUF_LENGTH);
 
-uint16_t buffer[2048];
+void sd_read_task(void *pvParameter) {
+  sdcard.open("/T1.wav");
+  for ( ;; ) {
+    uint16_t *start_ptr = ringbuf.getWrite();
+    size_t size_avail = ringbuf.getWriteAvail();
+    int num_samples = 0;
+    if (size_avail > 0) {
+      num_samples = sdcard.read(start_ptr, size_avail);
+      ringbuf.setWrite(num_samples);
+    }
+    Serial.print(num_samples,DEC);
+    Serial.println(" read samples from sdcard");
+
+    if (!sdcard.available()) break;		// EOF
+    vTaskDelay(20 / portTICK_PERIOD_MS);	// 20ms
+  }
+  Serial.println("sdcard: EOF");
+  sdcard.close();
+  vTaskDelete( NULL );
+}
+
+void i2s_write_task(void *pvParameter) {
+  for ( ;; ) {
+    TickType_t delay = 10 / portTICK_PERIOD_MS; // max delay: 10ms instead of portMAX_DELAY
+    uint16_t *start_ptr = ringbuf.getRead();
+    size_t size_avail = ringbuf.getReadAvail();
+    int num_samples = 0;
+    for (int i=0; i<size_avail; i++) {
+      unsigned int sample = ((unsigned short) start_ptr[i] << 16 & 0xffff0000) | ((unsigned short) start_ptr[i]);
+      int num_pushed_bytes = i2s_push_sample(sound.i2s_num, (char *)&sample, delay);
+      num_samples += num_pushed_bytes/4;
+    }
+    ringbuf.setRead(num_samples);
+    Serial.print(num_samples,DEC);
+    Serial.println(" pushed samples to i2s");
+    vTaskDelay(20 / portTICK_PERIOD_MS);
+  }
+  vTaskDelete( NULL );
+}
 
 void setup()
 {
@@ -34,20 +75,10 @@ void setup()
   keyboard.init();
   sdcard.mount();
   sound.init();
-  sdcard.open("/sabaton.wav");
-  int num_bytes_i = 0;
-  int num_bytes_o = 0;
-  while (sdcard.available()) {
-    num_bytes_i += sdcard.read(buffer, 2048);
-    num_bytes_o += sound.render_sample_block(buffer, buffer, 2048);
-    Serial.print(".");
-  }
-  sdcard.close();
-  Serial.println("");
-  Serial.print(num_bytes_i,DEC);
-  Serial.println(" bytes read from file");
-  Serial.print(num_bytes_o,DEC);
-  Serial.println(" bytes written to i2s");
+
+  xTaskCreate(&sd_read_task, "read_task", 2048, NULL, 5, NULL);
+  xTaskCreate(&i2s_write_task, "write_task", 1024,NULL,5,NULL );
+
   delay(1000);
 }
 
@@ -67,7 +98,7 @@ void loop()
     } else {
       // turn the LED off by making the voltage LOW
       digitalWrite(LED_PIN, LOW);
-      sound.stop();
+//      sound.stop();
     }
 
 

src/ringbuf.cpp

@@ -0,0 +1,49 @@
+#include "Arduino.h"
+
+#include "ringbuf.h"
+
+using namespace std;
+
+Ringbuf::Ringbuf(size_t buf_length) {
+  this->buf = (uint16_t *)malloc(buf_length);
+  Serial.print("Allocated buffer at: ");
+  Serial.println((int)this->buf,HEX);
+  this->buf_length = buf_length;
+  this->read_pos = 0;
+  this->write_pos = 0;
+  this->full = false;
+}
+
+Ringbuf::~Ringbuf() {
+  free(this->buf);
+}
+
+uint16_t *Ringbuf::getWrite() {
+  return this->buf + write_pos;
+}
+
+size_t Ringbuf::getWriteAvail() {
+  if (full)    return 0;					// full
+  else if (read_pos<=write_pos)       return buf_length - write_pos;		// to the end
+  else                                return read_pos - write_pos;		// between
+}
+
+uint16_t *Ringbuf::getRead() {
+  return this->buf + read_pos;
+}
+
+size_t Ringbuf::getReadAvail() {
+  if (read_pos==write_pos && !full)  return 0;					// empty
+  else if (read_pos>=write_pos)      return buf_length - read_pos;		// read til end
+  else                               return write_pos - read_pos;
+}
+
+void Ringbuf::setWrite(size_t bytes){
+  write_pos = (write_pos+bytes)%buf_length;
+  if(read_pos==write_pos) full = true;
+}
+
+void Ringbuf::setRead(size_t bytes){
+  read_pos = (read_pos+bytes)%buf_length;
+  if(read_pos==write_pos) full = false;
+}

src/ringbuf.h

@@ -0,0 +1,23 @@
+#ifndef _RINGBUF_H
+#define _RINGBUF_H
+
+
+class Ringbuf {
+  public:
+    Ringbuf(size_t buf_length);
+    ~Ringbuf();
+    uint16_t *buf;
+    unsigned int buf_length;
+    unsigned int read_pos;
+    unsigned int write_pos;
+    uint16_t *getWrite();
+    size_t getWriteAvail();
+    uint16_t *getRead();
+    size_t getReadAvail();
+    void setWrite(size_t bytes);
+    void setRead(size_t bytes);
+    bool full;
+  private:
+};
+
+#endif /* _RINGBUF_H */

src/sdcard.cpp

@@ -73,5 +73,5 @@ bool SDCard::available() {
 }
 
 size_t SDCard::read(uint16_t *buffer, size_t len){
-  return file.read((uint8_t *)buffer, len);
+  return file.read((uint8_t *)buffer, len*sizeof(uint16_t))/sizeof(uint16_t);
 }

src/sound.h

@@ -26,9 +26,10 @@ class Sound {
 //    void pause();
     void stop();
     int render_sample_block(uint16_t *sample_buf_left, uint16_t *sample_buf_right, int num_samples);
+    const i2s_port_t i2s_num = (i2s_port_t)I2S_NUM;
   private:
     i2sbuffer_t buffer;
-    const i2s_port_t i2s_num = (i2s_port_t)I2S_NUM;
+
 };
 
 #endif /* _SOUND_H */