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;
 	}
-
 };
+

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 ******************************************
  *

hardware_defines.h

@@ -1,5 +1,5 @@
 /*
- * hardware_defines.h.h
+ * hardware_defines.h
  *
  * This file is part of Mozzi.
  *
@@ -84,6 +84,13 @@
 #define IS_RENESAS() 0
 #endif
 
+// CH32 Architecture (WCH RISC-V)
+#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 +109,9 @@
 #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

internal/MozziGuts_impl_CH32.hpp

@@ -0,0 +1,160 @@
+/*
+ * MozziGuts_impl_CH32.hpp
+ *
+ * Implementation for WCH CH32X035 (RISC-V) using Standard Peripheral Library (SPL)
+ *
+ */
+
+// Suppress "narrowing conversion" error for CH32 (RISC-V GCC is strict)
+// This allows legacy Mozzi tables (declared as int8_t but containing uint8_t values) to compile.
+#pragma GCC diagnostic ignored "-Wnarrowing"
+
+#if !(IS_CH32())
+#  error "Wrong implementation included for this platform"
+#endif
+
+#if !defined(CH32X035)
+#  error "This CH32 chip is not supported by Mozzi yet. Only CH32X035 is currently supported."
+#endif
+
+#include <Arduino.h>
+
+// Forward declare the ISR to ensure C linkage
+extern "C" void TIM1_UP_IRQHandler(void) __attribute__((interrupt("WCH-Interrupt-fast")));
+
+namespace MozziPrivate {
+
+#define MOZZI_AUDIO_PIN_1 PA6 // High Byte (Main)
+#define MOZZI_AUDIO_PIN_2 PA7 // Low Byte (Fine tune) for 2PIN_PWM
+
+static void startAudio() {
+    // --- 1. Audio Interrupt Timer Setup (TIM1) ---
+    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
+    NVIC_InitTypeDef NVIC_InitStructure;
+
+    RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);
+
+    uint32_t period = (SystemCoreClock / MOZZI_AUDIO_RATE) - 1;
+
+    TIM_DeInit(TIM1);
+    TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
+    TIM_TimeBaseStructure.TIM_Prescaler = 0;
+    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
+    TIM_TimeBaseStructure.TIM_Period = period;
+    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
+    TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;
+    TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);
+
+    TIM_ClearFlag(TIM1, TIM_FLAG_Update);
+    TIM_ITConfig(TIM1, TIM_IT_Update, ENABLE);
+
+    NVIC_InitStructure.NVIC_IRQChannel = TIM1_UP_IRQn;
+    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
+    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
+    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
+    NVIC_Init(&NVIC_InitStructure);
+
+    TIM_Cmd(TIM1, ENABLE);
+    TIM_CtrlPWMOutputs(TIM1, ENABLE); 
+
+    // --- 2. PWM Output Setup (TIM3) ---
+    GPIO_InitTypeDef GPIO_InitStructure;
+    TIM_OCInitTypeDef TIM_OCInitStructure;
+
+    // Enable Clocks
+    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
+    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);
+
+    // Configure TIM3 Time Base
+    TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
+    TIM_TimeBaseStructure.TIM_Period = 255; // 8-bit resolution
+    TIM_TimeBaseStructure.TIM_Prescaler = 0;
+    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
+    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
+    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
+
+    // Common PWM Configuration
+    TIM_OCStructInit(&TIM_OCInitStructure);
+    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
+    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
+    TIM_OCInitStructure.TIM_Pulse = 128; 
+    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
+
+    // --- Setup Pin 1 (PA6 / CH1) ---
+    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
+    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
+    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
+    GPIO_Init(GPIOA, &GPIO_InitStructure);
+
+    TIM_OC1Init(TIM3, &TIM_OCInitStructure);
+    TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);
+
+#if MOZZI_IS(MOZZI_AUDIO_MODE, MOZZI_OUTPUT_2PIN_PWM)
+    // --- Setup Pin 2 (PA7 / CH2) for Hi-Fi ---
+    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
+    GPIO_Init(GPIOA, &GPIO_InitStructure); // Init PA7 as AF_PP too
+
+    TIM_OC2Init(TIM3, &TIM_OCInitStructure); // Init CH2
+    TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);
+#endif
+
+    TIM_ARRPreloadConfig(TIM3, ENABLE);
+
+    // Enable TIM3
+    TIM_Cmd(TIM3, ENABLE);
+    TIM_CtrlPWMOutputs(TIM3, ENABLE); 
+}
+
+void stopMozzi() {
+    TIM_Cmd(TIM1, DISABLE);
+    TIM_Cmd(TIM3, DISABLE);
+}
+
+void MozziRandPrivate::autoSeed() {}
+
+#if MOZZI_IS(MOZZI_ANALOG_READ, MOZZI_ANALOG_READ_STANDARD)
+void setupMozziADC(int8_t speed) {}
+void setupFastAnalogRead(int8_t speed) {}
+void adcStartConversion(uint8_t channel) {}
+void startSecondADCReadOnCurrentChannel() {}
+uint8_t adcPinToChannelNum(uint8_t pin) { return pin; }
+#endif
+
+// --- Audio Output Functions ---
+
+#if MOZZI_IS(MOZZI_AUDIO_MODE, MOZZI_OUTPUT_PWM)
+inline void audioOutput(const AudioOutput f) {
+    long out = (long)f.l() + MOZZI_AUDIO_BIAS; 
+    if (out < 0) out = 0;
+    out = out >> (MOZZI_AUDIO_BITS - 8); 
+    if (out > 255) out = 255;
+    TIM_SetCompare1(TIM3, (uint16_t)out);
+}
+
+#elif MOZZI_IS(MOZZI_AUDIO_MODE, MOZZI_OUTPUT_2PIN_PWM)
+inline void audioOutput(const AudioOutput f) {
+    // 16-bit output split into two 8-bit channels
+    long out = (long)f.l() + MOZZI_AUDIO_BIAS;
+
+    // Clamp to 16-bit unsigned range just in case
+    if (out < 0) out = 0;
+    if (out > 65535) out = 65535;
+
+    // High Byte -> CH1 (PA6)
+    TIM_SetCompare1(TIM3, (uint16_t)(out >> 8));
+
+    // Low Byte -> CH2 (PA7)
+    TIM_SetCompare2(TIM3, (uint16_t)(out & 0xFF));
+}
+#endif
+
+} // namespace MozziPrivate
+
+extern "C" void TIM1_UP_IRQHandler(void) {
+    if (TIM_GetITStatus(TIM1, TIM_IT_Update) != RESET) {
+        TIM_ClearITPendingBit(TIM1, TIM_IT_Update);
+#if (BYPASS_MOZZI_OUTPUT_BUFFER != true)
+        MozziPrivate::defaultAudioOutput();
+#endif
+    }
+}