Adds Wire::setBufferSize function

libraries/Wire/src/Wire.cpp

@@ -38,8 +38,11 @@ TwoWire::TwoWire(uint8_t bus_num)
     :num(bus_num & 1)
     ,sda(-1)
     ,scl(-1)
+    ,BufferSize(I2C_BUFFER_LENGTH) // default Wire Buffer Size
+    ,rxBuffer(NULL)
     ,rxIndex(0)
     ,rxLength(0)
+    ,txBuffer(NULL)
     ,txLength(0)
     ,txAddress(0)
     ,_timeOutMillis(50)
@@ -132,6 +135,81 @@ bool TwoWire::setPins(int sdaPin, int sclPin)
     return !i2cIsInit(num);
 }
 
+bool TwoWire::allocateWireBuffer(void)
+{
+    // or both buffer can be allocated or none will be
+    if (rxBuffer == NULL) {
+            rxBuffer = (uint8_t *)malloc(BufferSize);
+            if (rxBuffer == NULL) {
+                log_e("Can't allocate memory for I2C_%d rxBuffer", num);
+                return false;
+            }
+    }
+    if (txBuffer == NULL) {
+            txBuffer = (uint8_t *)malloc(BufferSize);
+            if (txBuffer == NULL) {
+                log_e("Can't allocate memory for I2C_%d txBuffer", num);
+                freeWireBuffer();  // free rxBuffer for safety!
+                return false;
+            }
+    }
+    // in case both were allocated before, they must have the same size. All good.
+    return true;
+}
+
+void TwoWire::freeWireBuffer(void)
+{
+    if (rxBuffer != NULL) {
+        free(rxBuffer);
+        rxBuffer = NULL;
+    }
+    if (txBuffer != NULL) {
+        free(txBuffer);
+        txBuffer = NULL;
+    }
+}
+
+size_t TwoWire::setBufferSize(size_t bSize)
+{
+    // Maximum size .... HEAP limited ;-)
+    if (bSize < 32) {    // 32 bytes is the I2C FIFO Len for ESP32/S2/S3/C3
+        log_e("Minimum Wire Buffer size is 32 bytes");
+        return 0;
+    }
+
+#if !CONFIG_DISABLE_HAL_LOCKS
+    if(lock != NULL){
+        //acquire lock
+        if(xSemaphoreTake(lock, portMAX_DELAY) != pdTRUE){
+            log_e("could not acquire lock");
+            return 0;
+        }
+#endif
+    // allocateWireBuffer allocates memory for both pointers or just free them
+    if (rxBuffer != NULL || txBuffer != NULL) {
+        // if begin() has been already executed, memory size changes... data may be lost. We don't care! :^)
+        if (bSize != BufferSize) {
+            // we want a new buffer size ... just reset buffer pointers and allocate new ones
+            freeWireBuffer();
+            BufferSize = bSize;
+            if (!allocateWireBuffer()) {
+                // failed! Error message already issued
+                bSize = 0; // returns error
+            }
+        } // else nothing changes, all set!
+    } else {
+        // no memory allocated yet, just change the size value - allocation in begin()
+        BufferSize = bSize;
+    }
+#if !CONFIG_DISABLE_HAL_LOCKS
+        //release lock
+        xSemaphoreGive(lock);
+    }
+#endif
+    return bSize;
+}
+
+
 // Slave Begin
 bool TwoWire::begin(uint8_t addr, int sdaPin, int sclPin, uint32_t frequency)
 {
@@ -159,11 +237,15 @@ bool TwoWire::begin(uint8_t addr, int sdaPin, int sclPin, uint32_t frequency)
         log_e("Bus already started in Master Mode.");
         goto end;
     }
+    if (!allocateWireBuffer()) {
+        // failed! Error Message already issued
+        goto end;
+    }
     if(!initPins(sdaPin, sclPin)){
         goto end;
     }
     i2cSlaveAttachCallbacks(num, onRequestService, onReceiveService, this);
-    if(i2cSlaveInit(num, sda, scl, addr, frequency, I2C_BUFFER_LENGTH, I2C_BUFFER_LENGTH) != ESP_OK){
+    if(i2cSlaveInit(num, sda, scl, addr, frequency, BufferSize, BufferSize) != ESP_OK){
         log_e("Slave Init ERROR");
         goto end;
     }
@@ -205,6 +287,10 @@ bool TwoWire::begin(int sdaPin, int sclPin, uint32_t frequency)
         started = true;
         goto end;
     }
+    if (!allocateWireBuffer()) {
+        // failed! Error Message already issued
+        goto end;
+    }
     if(!initPins(sdaPin, sclPin)){
         goto end;
     }
@@ -239,6 +325,7 @@ bool TwoWire::end()
         } else if(i2cIsInit(num)){
             err = i2cDeinit(num);
         }
+        freeWireBuffer();
 #if !CONFIG_DISABLE_HAL_LOCKS
         //release lock
         xSemaphoreGive(lock);
@@ -325,12 +412,26 @@ void TwoWire::beginTransmission(uint16_t address)
     txLength = 0;
 }
 
+/*
+https://www.arduino.cc/reference/en/language/functions/communication/wire/endtransmission/
+endTransmission() returns:
+0: success.
+1: data too long to fit in transmit buffer.
+2: received NACK on transmit of address.
+3: received NACK on transmit of data.
+4: other error.
+5: timeout
+*/
 uint8_t TwoWire::endTransmission(bool sendStop)
 {
     if(is_slave){
         log_e("Bus is in Slave Mode");
         return 4;
     }
+    if (txBuffer == NULL){
+        log_e("NULL TX buffer pointer");
+        return 4;
+    }
     esp_err_t err = ESP_OK;
     if(sendStop){
         err = i2cWrite(num, txAddress, txBuffer, txLength, _timeOutMillis);
@@ -360,6 +461,10 @@ size_t TwoWire::requestFrom(uint16_t address, size_t size, bool sendStop)
         log_e("Bus is in Slave Mode");
         return 0;
     }
+    if (rxBuffer == NULL || txBuffer == NULL){
+        log_e("NULL buffer pointer");
+        return 0;
+    }
     esp_err_t err = ESP_OK;
     if(nonStop
 #if !CONFIG_DISABLE_HAL_LOCKS
@@ -401,7 +506,11 @@ size_t TwoWire::requestFrom(uint16_t address, size_t size, bool sendStop)
 
 size_t TwoWire::write(uint8_t data)
 {
-    if(txLength >= I2C_BUFFER_LENGTH) {
+    if (txBuffer == NULL){
+        log_e("NULL TX buffer pointer");
+        return 0;
+    }
+    if(txLength >= BufferSize) {
         return 0;
     }
     txBuffer[txLength++] = data;
@@ -428,6 +537,10 @@ int TwoWire::available(void)
 int TwoWire::read(void)
 {
     int value = -1;
+    if (rxBuffer == NULL){
+        log_e("NULL RX buffer pointer");
+        return value;
+    }
     if(rxIndex < rxLength) {
         value = rxBuffer[rxIndex++];
     }
@@ -437,6 +550,10 @@ int TwoWire::read(void)
 int TwoWire::peek(void)
 {
     int value = -1;
+    if (rxBuffer == NULL){
+        log_e("NULL RX buffer pointer");
+        return value;
+    }
     if(rxIndex < rxLength) {
         value = rxBuffer[rxIndex];
     }
@@ -520,6 +637,10 @@ void TwoWire::onReceiveService(uint8_t num, uint8_t* inBytes, size_t numBytes, b
     if(!wire->user_onReceive){
         return;
     }
+    if (wire->rxBuffer == NULL){
+        log_e("NULL RX buffer pointer");
+        return;
+    }
     for(uint8_t i = 0; i < numBytes; ++i){
         wire->rxBuffer[i] = inBytes[i];    
     }
@@ -534,6 +655,10 @@ void TwoWire::onRequestService(uint8_t num, void * arg)
     if(!wire->user_onRequest){
         return;
     }
+    if (wire->txBuffer == NULL){
+        log_e("NULL TX buffer pointer");
+        return;
+    }
     wire->txLength = 0;
     wire->user_onRequest();
     if(wire->txLength){

libraries/Wire/src/Wire.h

@@ -34,8 +34,9 @@
 #endif
 #include "Stream.h"
 
+#define WIRE_HAS_BUFFER_SIZE    1
 #ifndef I2C_BUFFER_LENGTH
-    #define I2C_BUFFER_LENGTH 128
+    #define I2C_BUFFER_LENGTH 128  // Default size, if none is set using Wire::setBuffersize(size_t)
 #endif
 typedef void(*user_onRequest)(void);
 typedef void(*user_onReceive)(uint8_t*, int);
@@ -47,11 +48,12 @@ class TwoWire: public Stream
     int8_t sda;
     int8_t scl;
 
-    uint8_t rxBuffer[I2C_BUFFER_LENGTH];
+    size_t BufferSize;
+    uint8_t *rxBuffer;
     size_t rxIndex;
     size_t rxLength;
 
-    uint8_t txBuffer[I2C_BUFFER_LENGTH];
+    uint8_t *txBuffer;
     size_t txLength;
     uint16_t txAddress;
 
@@ -68,6 +70,8 @@ class TwoWire: public Stream
     static void onRequestService(uint8_t, void *);
     static void onReceiveService(uint8_t, uint8_t*, size_t, bool, void *);
     bool initPins(int sdaPin, int sclPin);
+    bool allocateWireBuffer(void);
+    void freeWireBuffer(void);
 
 public:
     TwoWire(uint8_t bus_num);
@@ -93,6 +97,8 @@ class TwoWire: public Stream
     }
     bool end();
 
+    size_t setBufferSize(size_t bSize);
+
     void setTimeOut(uint16_t timeOutMillis); // default timeout of i2c transactions is 50ms
     uint16_t getTimeOut();