i2s enhancements

cores/esp8266/core_esp8266_i2s.c

@@ -66,7 +66,7 @@ bool ICACHE_FLASH_ATTR i2s_is_empty(){
 }
 
 int16_t ICACHE_FLASH_ATTR i2s_available(){
-	return (SLC_BUF_CNT - i2s_slc_queue_len) * SLC_BUF_LEN;
+	return (i2s_slc_queue_len * SLC_BUF_LEN) + (SLC_BUF_LEN - i2s_curr_slc_buf_pos);
 }
 
 uint32_t ICACHE_FLASH_ATTR i2s_slc_queue_next_item(){ //pop the top off the queue
@@ -195,6 +195,47 @@ bool ICACHE_FLASH_ATTR i2s_write_sample_nb(uint32_t sample) {
   return true;
 }
 
+#define MIN(a,b) (a<b?a:b)
+
+// writes a buffer of samples into the DMA memory, returns the amount of samples written
+int16_t ICACHE_FLASH_ATTR i2s_write_buffer_mono(int16_t *sample, int16_t len) {
+	int16_t samples_written=0;
+
+	for(;;)	{
+		// make sure we have room in the current buffer
+		if (i2s_curr_slc_buf_pos==SLC_BUF_LEN || i2s_curr_slc_buf==NULL){
+			// no room in the current buffer? if there are no buffers available then exit
+			if(i2s_slc_queue_len == 0)
+				break;
+
+			// get a new buffer
+			ETS_SLC_INTR_DISABLE();
+			i2s_curr_slc_buf = (uint32_t *)i2s_slc_queue_next_item();
+			ETS_SLC_INTR_ENABLE();
+			i2s_curr_slc_buf_pos=0;		
+		}
+
+		if (len==0)
+			break;
+
+		//space available in the current buffer
+		int16_t	available = SLC_BUF_LEN - i2s_curr_slc_buf_pos;
+
+		int16_t m = MIN(available,len);
+
+		for(int16_t i=0;i<m;i++){
+			int16_t v =	(*sample);
+			uint32_t vv = (v<<16) | (v & 0xffff);
+			i2s_curr_slc_buf[i2s_curr_slc_buf_pos++] = vv;
+			sample++;
+		}
+		len -= m;
+		samples_written += m;
+	}	
+	return samples_written;
+}
+
+
 bool ICACHE_FLASH_ATTR i2s_write_lr(int16_t left, int16_t right){
   int sample = right & 0xFFFF;
   sample = sample << 16;

cores/esp8266/i2s.h

@@ -49,6 +49,7 @@ bool i2s_write_lr(int16_t left, int16_t right);//combines both channels and call
 bool i2s_is_full();//returns true if DMA is full and can not take more bytes (overflow)
 bool i2s_is_empty();//returns true if DMA is empty (underflow)
 int16_t i2s_available();// returns the number of samples than can be written before blocking
+int16_t ICACHE_FLASH_ATTR i2s_write_buffer_mono(int16_t *sample, int16_t len); //writes a number of samplers in the the DMA mem, returns the numner of written samples
 
 #ifdef __cplusplus
 }