i2s can send now buffers

cores/esp8266/core_esp8266_i2s.c

@@ -331,6 +331,74 @@ bool i2s_write_lr(int16_t left, int16_t right){
   return i2s_write_sample(sample);
 }
 
+// writes a buffer of frames into the DMA memory, returns the amount of frames written
+// A frame is just a int16_t for mono, for stereo a frame is two int16_t, one for each channel.
+static int16_t _i2s_write_buffer(int16_t *frames, int16_t frame_count, bool mono, bool nb) {
+    int16_t frames_written=0;
+
+    while(frame_count>0) {
+
+        // make sure we have room in the current buffer
+        if (tx->curr_slc_buf_pos==SLC_BUF_LEN || tx->curr_slc_buf==NULL) {
+            // no room in the current buffer? if there are no buffers available then exit
+            if (tx->slc_queue_len == 0)
+            {
+                if (nb) {
+                    // if nonblocking just return the number of frames written so far
+                    break;
+                }
+                else {
+                    while (1) {
+                        if (tx->slc_queue_len > 0) {
+                          break;
+                        } else {
+                          optimistic_yield(10000);
+                        }
+                    }
+                }
+            }
+
+            // get a new buffer
+            ETS_SLC_INTR_DISABLE();
+            tx->curr_slc_buf = (uint32_t *)i2s_slc_queue_next_item(tx);
+            ETS_SLC_INTR_ENABLE();
+            tx->curr_slc_buf_pos=0;
+        }       
+
+        //space available in the current buffer
+        int16_t	available = SLC_BUF_LEN - tx->curr_slc_buf_pos;
+
+        int16_t fc = (available < frame_count) ? available : frame_count;
+
+        if (mono) {
+            for(int16_t i=0;i<fc;i++){
+                uint16_t v = (uint16_t)(*frames++);
+                tx->curr_slc_buf[tx->curr_slc_buf_pos++] = (v << 16) | v;               
+            }                
+        }
+        else
+        {        
+            for(int16_t i=0;i<fc;i++){
+                uint16_t v1 = *frames++;
+                uint16_t v2 = *frames++;
+                tx->curr_slc_buf[tx->curr_slc_buf_pos++] = (v1 << 16) | v2;
+            }
+        }        
+
+        frame_count -= fc;
+        frames_written += fc;
+    }
+    return frames_written;
+}
+
+int16_t i2s_write_buffer_mono_nb(int16_t *frames, int16_t frame_count) { return _i2s_write_buffer(frames, frame_count, true, true); }
+
+int16_t i2s_write_buffer_mono(int16_t *frames, int16_t frame_count) { return _i2s_write_buffer(frames, frame_count, true, false); }
+
+int16_t i2s_write_buffer_nb(int16_t *frames, int16_t frame_count) { return _i2s_write_buffer(frames, frame_count, false, true); }
+
+int16_t i2s_write_buffer(int16_t *frames, int16_t frame_count) { return _i2s_write_buffer(frames, frame_count, false, false); }
+
 bool i2s_read_sample(int16_t *left, int16_t *right, bool blocking) {
   if (!rx) {
     return false;

cores/esp8266/i2s.h

@@ -59,6 +59,13 @@ int16_t i2s_rx_available();// returns the number of samples than can be written
 void i2s_set_callback(void (*callback) (void));
 void i2s_rx_set_callback(void (*callback) (void));
 
+// writes a buffer of frames into the DMA memory, returns the amount of frames written
+// A frame is just a int16_t for mono, for stereo a frame is two int16_t, one for each channel.
+int16_t i2s_write_buffer_mono(int16_t *frames, int16_t frame_count);
+int16_t i2s_write_buffer_mono_nb(int16_t *frames, int16_t frame_count);
+int16_t i2s_write_buffer(int16_t *frames, int16_t frame_count);
+int16_t i2s_write_buffer_nb(int16_t *frames, int16_t frame_count); 
+
 #ifdef __cplusplus
 }
 #endif