Modified CircularBuffer to have the buffer size as a template

parameter hence allowing for differently sized bufers to be used (for
instance with audio input)

Author: tomcombriat

CircularBuffer.h

@@ -19,36 +19,13 @@ April 2025: modified for different buffer sizes under the suggestion
 of Meebleeps (https://github.com/sensorium/Mozzi/issues/281)
 */
 
-// TODO: remove this define from here, put a default value in config
-#define MOZZI_OUTPUT_BUFFER_SIZE 256
-
-// This is to get the correct cound for audioticks() (there might be a smarter way...)
-#if (MOZZI_OUTPUT_BUFFER_SIZE == 256)
-#define COUNT_LSHIFT 8
-#elif (MOZZI_OUTPUT_BUFFER_SIZE == 128)
-#define COUNT_LSHIFT 7
-#elif (MOZZI_OUTPUT_BUFFER_SIZE == 64)
-#define COUNT_LSHIFT 6
-#elif (MOZZI_OUTPUT_BUFFER_SIZE == 32)
-#define COUNT_LSHIFT 5
-#elif (MOZZI_OUTPUT_BUFFER_SIZE == 16)
-#define COUNT_LSHIFT 4
-#elif (MOZZI_OUTPUT_BUFFER_SIZE == 8)
-#define COUNT_LSHIFT 3
-#elif (MOZZI_OUTPUT_BUFFER_SIZE == 4)
-#define COUNT_LSHIFT 2
-#elif (MOZZI_OUTPUT_BUFFER_SIZE == 2)
-#define COUNT_LSHIFT 1
-#elif (MOZZI_OUTPUT_BUFFER_SIZE == 1)
-#define COUNT_LSHIFT 0
-#endif
-
-
-
-/** Circular buffer object.  Has a fixed number of cells, set to 256.
+
+
+/** Circular buffer object.  Has a fixed number of cells, set by BUFFER_SIZE.
 @tparam ITEM_TYPE the kind of data to store, eg. int, int8_t etc.
+@tparam BUFFER_SIZE the size of the circular buffer
 */
-template <class ITEM_TYPE>
+template <class ITEM_TYPE, int16_t BUFFER_SIZE>
 class CircularBuffer
 {
 
@@ -93,33 +70,26 @@ class CircularBuffer
 	}
 
 private:
-	ITEM_TYPE items[MOZZI_OUTPUT_BUFFER_SIZE];
+	ITEM_TYPE items[BUFFER_SIZE];
 	uint8_t         start;  /* index of oldest itement              */
 	uint8_t         end;    /* index at which to write new itement  */
 	uint8_t         s_msb;
 	uint8_t         e_msb;
 	unsigned long num_buffers_read;
+    static constexpr unsigned long COUNT_LSHIFT = 
+        (BUFFER_SIZE == 256) ? 8 :
+        (BUFFER_SIZE == 128) ? 7 :
+        (BUFFER_SIZE == 64) ? 6 :
+        (BUFFER_SIZE == 32) ? 5 :
+        (BUFFER_SIZE == 16) ? 4 :
+        (BUFFER_SIZE == 8) ? 3 :
+        (BUFFER_SIZE == 4) ? 2 :
+        (BUFFER_SIZE == 2) ? 1 : 0;
 
-#if (MOZZI_OUTPUT_BUFFER_SIZE == 256)
-	inline
-	void cbIncrStart() {
-		start++;
-		if (start == 0) {
-			s_msb ^= 1;
-			num_buffers_read++;
-		}
-	}
-
-	inline
-	void cbIncrEnd() {
-		end++;
-		if (end == 0) e_msb ^= 1;
-	}
-#else // if circular buffer length is != 256, use less efficient version for to manage start/end index buffer index
   inline
   void cbIncrStart()  {
     start++;
-    if (start == MOZZI_OUTPUT_BUFFER_SIZE)
+    if (start == BUFFER_SIZE)
       {
 	start = 0;
 	s_msb ^= 1;
@@ -131,16 +101,88 @@ class CircularBuffer
   void cbIncrEnd()
   {
     end++;
-    if (end == MOZZI_OUTPUT_BUFFER_SIZE)
+    if (end == BUFFER_SIZE)
       {
 	end = 0;
 	e_msb ^= 1;
       }
   }
-#endif
 
 
 };
 
 
-#undef COUNT_LSHIFT // avoid macro spil
+
+/** Circular buffer object.  Specialization for size of 256.
+Note: Lot of duplication but C++ does not allow for specialization of the 
+function member only (partial specialization).
+@tparam ITEM_TYPE the kind of data to store, eg. int, int8_t etc.
+*/
+template <class ITEM_TYPE>
+class CircularBuffer<ITEM_TYPE, 256>
+{
+public:
+	/** Constructor
+	*/
+	CircularBuffer(): start(0),end(0),s_msb(0),e_msb(0)
+	{
+	}
+
+	inline
+	bool isFull() {
+		return end == start && e_msb != s_msb;
+	}
+
+	inline
+	bool isEmpty() {
+		return end == start && e_msb == s_msb;
+	}
+
+	inline
+	void write(ITEM_TYPE in) {
+		items[end] = in;
+		//if (isFull()) cbIncrStart(); /* full, overwrite moves start pointer */
+		cbIncrEnd();
+	}
+
+	inline
+	ITEM_TYPE read() {
+		ITEM_TYPE out = items[start];
+		cbIncrStart();
+		return out;
+	}
+
+	inline
+	unsigned long count() {
+		return (num_buffers_read << 8) + start;
+	}
+        inline
+	ITEM_TYPE * address() {
+	  return items;
+	}
+
+private:
+	ITEM_TYPE items[256];
+	uint8_t         start;  /* index of oldest itement              */
+	uint8_t         end;    /* index at which to write new itement  */
+	uint8_t         s_msb;
+	uint8_t         e_msb;
+	unsigned long num_buffers_read;
+
+
+	inline
+	void cbIncrStart() {
+		start++;
+		if (start == 0) {
+			s_msb ^= 1;
+			num_buffers_read++;
+		}
+	}
+
+	inline
+	void cbIncrEnd() {
+		end++;
+		if (end == 0) e_msb ^= 1;
+	}
+};
+