Add support for CH32X035 architecture

CircularBuffer.h

@@ -14,19 +14,113 @@ Modified from https://en.wikipedia.org/wiki/Circular_buffer
 Mirroring version
 On 18 April 2014, the simplified version on the Wikipedia page for power of 2 sized buffers 
 doesn't work - cbIsEmpty() returns true whether the buffer is full or empty.
+
+April 2025: modified for different buffer sizes under the suggestion
+of Meebleeps (https://github.com/sensorium/Mozzi/issues/281)
 */
 
-#define MOZZI_BUFFER_SIZE 256 // do not expect to change and it to work.
-                              // just here for forward compatibility if one day
-                              // the buffer size might be editable
 
-/** 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
 {
 
+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 << COUNT_LSHIFT) + start;
+	}
+        inline
+	ITEM_TYPE * address() {
+	  return items;
+	}
+
+private:
+	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;
+
+  inline
+  void cbIncrStart()  {
+    start++;
+    if (start == BUFFER_SIZE)
+      {
+	start = 0;
+	s_msb ^= 1;
+	num_buffers_read++;
+      }
+  }
+
+  inline
+  void cbIncrEnd()
+  {
+    end++;
+    if (end == BUFFER_SIZE)
+      {
+	end = 0;
+	e_msb ^= 1;
+      }
+  }
+
+
+};
+
+
+
+/** 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
 	*/
@@ -68,7 +162,7 @@ class CircularBuffer
 	}
 
 private:
-	ITEM_TYPE items[MOZZI_BUFFER_SIZE];
+	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;
@@ -90,5 +184,5 @@ class CircularBuffer
 		end++;
 		if (end == 0) e_msb ^= 1;
 	}
-
 };
+

README.md

@@ -16,7 +16,7 @@ passing or external synths.
 ***
 
 ## Features
--    Available for a wide and growing range of MCUs, with and without inbuilt DACs: Arduino Uno R3 and R4, STM32, Teensy, ESP8266, ESP32, Raspberry Pi Pico, and more.
+-    Available for a wide and growing range of MCUs, with and without inbuilt DACs: Arduino Uno R3 and R4, STM32, Teensy, ESP8266, ESP32, Raspberry Pi Pico, CH32, and more.
 -    Configurable sample rate, usually in powers of two (16384 Hz, or 32768 Hz).
 -    Variable control rate from 64 Hz upwards.
 -    Various inbuilt output modes, including 16 bit output to an external DAC.
@@ -69,6 +69,7 @@ If desparate, there is still a "Mozzi_1" branch in the git repository which cont
 | *ESP32: that has an external DAC (only ESP32) note: Beware of vastly different pin labels across board variants* | 15 (+16)  |  | yes | **GPIO25 (+GPIO26)** | yes |
 | *ESP32-S/C/H/P: that do not have an external DAC note: Beware of vastly different pin labels across board variants* | **15 (+16)**  |  | yes |  | yes |
 | *RP2040*: Raspberry Pi Pico and friends  | **0 (+1)** | 0, 1 |  |  | yes |
+| *CH32*: WCH CH32X035 (RISC-V) | **PA6** | PA6, PA7 | | | |
 
 > - PWM-1: 1-pin PWM mode (`MOZZI_OUTPUT_PWM`)
 > - PWM-2: 2-pin PWM mode (`MOZZI_OUTPUT_2PIN_PWM`)

config/mozzi_config_documentation.h

@@ -249,6 +249,22 @@
  * */
 #define MOZZI_AUDIO_PIN_1 FOR_DOXYGEN_ONLY
 
+/** @ingroup config
+ * @def MOZZI_OUTPUT_BUFFER_SIZE
+ *
+ * @brief Audio buffer setting.
+ *
+ * For a lot of outputting modes, Mozzi is buffering the audio samples in order to be able to coop with varying loads on the processor.
+ * The bigger the buffer, the more able Mozzi will be to coop with big change of processor loads as the buffered values can compensate for that.
+ * At the same time, a bigger buffer produces a bigger latency as the time between when Mozzi produces the sample and the time it is actually outputted increases. For instance, for a long time Mozzi's buffer size was of a fixed size of 256. This produces a potential latency of 15.6 ms for a MOZZI_AUDIO_RATE of 16384, and half this value for a MOZZI_AUDIO_RATE of 32768.
+ * Depending on the application, this is usually not a problem but can lead to synchronisation issues in some cases (for instance when working with clocks).
+ * MOZZI_OUTPUT_BUFFER_SIZE can be reduced to smaller values with this config, leading to more accurate timings but potentially to glitches if the buffer runs low.
+ * Valid values are power of two from 256 downward (128, 64, …).
+ * Note that this might not have an effect in all modes/platforms combination as Mozzi is sometimes using an external buffer which is not always configurable.
+ *
+*/
+#define MOZZI_OUTPUT_BUFFER_SIZE FOR_DOXYGEN_ONLY
+
 
 /***************************************** ADVANCED SETTTINGS -- External audio output ******************************************
  *

extras/website/_includes/boards-tested.markdown

@@ -47,6 +47,8 @@ td[data-sd] { border: 2px solid; background: linear-gradient(-45deg,rgba(0,0,255
     <td><i>ESP32-S/C/H/P</i>: that do not have an internal DAC <i>note: Beware of vastly different pin labels across board variants</i>  </td><td data-sd>15 (+16) </td><td>                 </td><td data-mo>yes </td><td></td><td data-st>yes</td></tr>
 <tr style="border-top: 1px solid">
     <td><i>RP2040</i>: Raspberry Pi Pico and friends                                            </td><td data-sd>0 (+1)  </td><td data-mo>0, 1       </td><td> -          </td><td> -          </td><td data-st>yes </td></tr>
+<tr style="border-top: 1px solid">
+    <td><i>CH32</i>: WCH CH32X035 (RISC-V)                                                     </td><td data-md>PA6     </td><td data-mo>PA6, PA7 </td><td> -          </td><td> -          </td><td> -          </td></tr>
 </tbody>
 </table>
 

extras/website/index.markdown

@@ -58,7 +58,7 @@ Your browser does not support the audio element. </audio>
 
 
 ## Features
--    Available for a wide and growing range of MCUs, with and without inbuilt DACs: Arduino Uno R3 and R4, STM32, Teensy, ESP8266, ESP32, Raspberry Pi Pico, and more.
+-    Available for a wide and growing range of MCUs, with and without inbuilt DACs: Arduino Uno R3 and R4, STM32, Teensy, ESP8266, ESP32, Raspberry Pi Pico, CH32, and more.
 -    Configurable sample rate, usually in powers of two (16384 Hz, or 32768 Hz).
 -    Variable control rate from 64 Hz upwards.
 -    Various inbuilt output modes, including 16 bit output to an external DAC.

hardware_defines.h

@@ -1,5 +1,5 @@
 /*
- * hardware_defines.h.h
+ * hardware_defines.h
  *
  * This file is part of Mozzi.
  *
@@ -84,6 +84,14 @@
 #define IS_RENESAS() 0
 #endif
 
+// CH32 Architecture (WCH RISC-V)
+// Explicit check for CH32X035 is needed as ARDUINO_ARCH macros might not be defined by all cores/tools
+#if (defined(ARDUINO_ARCH_CH32V) || defined(ARDUINO_ARCH_CH32) || defined(CH32X035))
+#define IS_CH32() 1
+#else
+#define IS_CH32() 0
+#endif
+
 #if (defined(__arm__) && !IS_STM32MAPLE() && !IS_TEENSY3() && !IS_TEENSY4() && !IS_RP2040() && !IS_SAMD21() && !IS_MBED() && !IS_RENESAS())
 #define IS_STM32DUINO() 1
 #else
@@ -102,9 +110,9 @@
 #define IS_ESP32() 0
 #endif
 
-#if !(IS_AVR() || IS_TEENSY3() || IS_TEENSY4() || IS_STM32MAPLE() || IS_STM32DUINO() || IS_ESP8266() || IS_SAMD21() || IS_ESP32() || IS_RP2040() || IS_MBED() || IS_RENESAS())
+#if !(IS_AVR() || IS_TEENSY3() || IS_TEENSY4() || IS_STM32MAPLE() || IS_STM32DUINO() || IS_ESP8266() || IS_SAMD21() || IS_ESP32() || IS_RP2040() || IS_MBED() || IS_RENESAS() || IS_CH32())
 // TODO: add an exception for MOZZI_OUTPUT_EXTERNAL_CUSTOM
-#error Your hardware is not supported by Mozzi or not recognized. Edit hardware_defines.h to proceed.
+#error Your hardware is not supported by Mozzi or not recognized. Edit hardware_defines.h to proceed.    
 #endif
 
 // Hardware detail defines

internal/MozziGuts.hpp

@@ -61,6 +61,8 @@ template<byte BITS_IN, byte BITS_OUT, typename T> constexpr T smartShift(T value
 #  include "MozziGuts_impl_MBED.hpp"
 #elif (IS_RENESAS())
 #  include "MozziGuts_impl_RENESAS.hpp"
+#elif (IS_CH32())
+#  include "MozziGuts_impl_CH32.hpp"
 #else
 #  error "Platform not (yet) supported. Check MozziGuts_impl_template.hpp and existing implementations for a blueprint for adding your favorite MCU."
 #endif
@@ -86,7 +88,7 @@ inline void bufferAudioOutput(const AudioOutput f) {
   ++samples_written_to_buffer;
 }
 #else
-CircularBuffer<AudioOutput> output_buffer;  // fixed size 256
+  CircularBuffer<AudioOutput, MOZZI_OUTPUT_BUFFER_SIZE> output_buffer; 
 #  define canBufferAudioOutput() (!output_buffer.isFull())
 #  define bufferAudioOutput(f) output_buffer.write(f)
 static void CACHED_FUNCTION_ATTR defaultAudioOutput() {
@@ -150,7 +152,7 @@ uint16_t getAudioInput() { return audio_input; }
 
 #if MOZZI_IS(MOZZI__LEGACY_AUDIO_INPUT_IMPL, 1)
 // ring buffer for audio input
-CircularBuffer<uint16_t> input_buffer; // fixed size 256
+  CircularBuffer<uint16_t, 256> input_buffer; // fixed size 256
 #define audioInputAvailable() (!input_buffer.isEmpty())
 #define readAudioInput() (input_buffer.read())
 /** NOTE: Triggered at MOZZI_AUDIO_RATE via defaultAudioOutput(). In addition to the MOZZI_AUDIO_INPUT_PIN, at most one reading is taken for mozziAnalogRead().  */
@@ -319,4 +321,4 @@ MOZZI_DEPRECATED("n/a", "Sketch has audioOutput() function, although external ou
 #if !MOZZI_IS(MOZZI_AUDIO_MODE, MOZZI_OUTPUT_EXTERNAL_CUSTOM)
 // TODO: This won't work without a rename:
 //MOZZI_DEPRECATED("n/a", "Sketch has canBufferAudioOutput() function, although custom external output is not configured.") bool canBufferAudioOutput() {};
-#endif
+#endif