Add bytebuffer support to ringbuf.c

components/freertos/include/freertos/ringbuf.h

@@ -18,22 +18,34 @@ to this bit of memory will block.
 
 The requirement for items to be contiguous is slightly problematic when the only way to place
 the next item would involve a wraparound from the end to the beginning of the ringbuffer. This can
-be solved in two ways:
-- allow_split_items = pdTRUE: The insertion code will split the item in two items; one which fits
+be solved (or not) in a few ways:
+- type = RINGBUF_TYPE_ALLOWSPLIT: The insertion code will split the item in two items; one which fits
 in the space left at the end of the ringbuffer, one that contains the remaining data which is placed
 in the beginning. Two xRingbufferReceive calls will be needed to retrieve the data.
-- allow_split_items = pdFALSE: The insertion code will leave the room at the end of the ringbuffer
+- type = RINGBUF_TYPE_NOSPLIT: The insertion code will leave the room at the end of the ringbuffer
 unused and instead will put the entire item at the start of the ringbuffer, as soon as there is 
 enough free space.
+- type = RINGBUF_TYPE_BYTEBUF: This is your conventional byte-based ringbuffer. It does have no
+overhead, but it has no item contiguousness either: a read will just give you the entire written
+buffer space, or the space up to the end of the buffer, and writes can be broken up in any way 
+possible. Note that this type cannot do a 2nd read before returning the memory of the 1st.
 
 The maximum size of an item will be affected by this decision. When split items are allowed, it's
 acceptable to push items of (buffer_size)-16 bytes into the buffer. When it's not allowed, the
-maximum size is (buffer_size/2)-8 bytes.
+maximum size is (buffer_size/2)-8 bytes. The bytebuf can fill the entire buffer with data, it has
+no overhead.
 */
 
 //An opaque handle for a ringbuff object.
 typedef void * RingbufHandle_t;
 
+//The various types of buffer
+typedef enum {
+	RINGBUF_TYPE_NOSPLIT = 0,
+	RINGBUF_TYPE_ALLOWSPLIT,
+	RINGBUF_TYPE_BYTEBUF
+} ringbuf_type_t;
+
 
 /**
  * @brief  Create a ring buffer
@@ -45,7 +57,7 @@ typedef void * RingbufHandle_t;
  *
  * @return A RingbufHandle_t handle to the created ringbuffer, or NULL in case of error.
  */
-RingbufHandle_t xRingbufferCreate(size_t buf_length, BaseType_t allow_split_items);
+RingbufHandle_t xRingbufferCreate(size_t buf_length, ringbuf_type_t type);
 
 
 /**
@@ -120,6 +132,34 @@ void *xRingbufferReceive(RingbufHandle_t ringbuf, size_t *item_size, TickType_t
 void *xRingbufferReceiveFromISR(RingbufHandle_t ringbuf, size_t *item_size);
 
 
+/**
+ * @brief  Retrieve bytes from a ByteBuf type of ring buffer, specifying the maximum amount of bytes
+ * to return
+ *
+ * @param  ringbuf - Ring buffer to retrieve the item from
+ * @param  item_size - Pointer to a variable to which the size of the retrieved item will be written.
+ * @param  xTicksToWait - Ticks to wait for items in the ringbuffer.
+ *
+ * @return Pointer to the retrieved item on success; *item_size filled with the length of the 
+ *         item. NULL on timeout, *item_size is untouched in that case.
+ */
+void *xRingbufferReceiveUpTo(RingbufHandle_t ringbuf, size_t *item_size, TickType_t ticks_to_wait, size_t wanted_size);
+
+
+/**
+ * @brief  Retrieve bytes from a ByteBuf type of ring buffer, specifying the maximum amount of bytes
+ * to return. Call this from an ISR.
+ *
+ * @param  ringbuf - Ring buffer to retrieve the item from
+ * @param  item_size - Pointer to a variable to which the size of the retrieved item will be written.
+ *
+ * @return Pointer to the retrieved item on success; *item_size filled with the length of the 
+ *         item. NULL when the ringbuffer is empty, *item_size is untouched in that case.
+ */
+void *xRingbufferReceiveUpToFromISR(RingbufHandle_t ringbuf, size_t *item_size, size_t wanted_size);
+
+
+
 /**
  * @brief  Return a previously-retrieved item to the ringbuffer
  *

components/freertos/ringbuf.c

@@ -18,6 +18,7 @@
 #include "freertos/queue.h"
 #include "freertos/xtensa_api.h"
 #include "freertos/ringbuf.h"
+#include "esp_attr.h"
 #include <stdint.h>
 #include <string.h>
 #include <stdlib.h>
@@ -25,6 +26,7 @@
 
 typedef enum {
     flag_allowsplit = 1,
+    flag_bytebuf = 2,
 } rbflag_t;
 
 typedef enum {
@@ -33,8 +35,10 @@ typedef enum {
 } itemflag_t;
 
 
+typedef struct ringbuf_t ringbuf_t;
+
 //The ringbuffer structure
-typedef struct {
+struct  ringbuf_t {
     SemaphoreHandle_t free_space_sem;           //Binary semaphore, wakes up writing threads when there's more free space
     SemaphoreHandle_t items_buffered_sem;       //Binary semaphore, indicates there are new packets in the circular buffer. See remark.
     size_t size;                                //Size of the data storage
@@ -44,7 +48,12 @@ typedef struct {
     uint8_t *data;                              //Data storage
     portMUX_TYPE mux;                           //Spinlock for actual data/ptr/struct modification
     rbflag_t flags;
-} ringbuf_t;
+    size_t maxItemSize;
+   //The following keep function pointers to hold different implementations for ringbuffer management.
+    BaseType_t (*copyItemToRingbufImpl)(ringbuf_t *rb, uint8_t *buffer, size_t buffer_size);
+    uint8_t *(*getItemFromRingbufImpl)(ringbuf_t *rb, size_t *length, int wanted_length);
+    void (*returnItemToRingbufImpl)(ringbuf_t *rb, void *item);
+};
 
 
 
@@ -73,14 +82,81 @@ static int ringbufferFreeMem(ringbuf_t *rb)
     return free_size-1;
 }
 
-//Copies a single item to the ring buffer. Assumes there is space in the ringbuffer and
+
+//Copies a single item to the ring buffer; refuses to split items. Assumes there is space in the ringbuffer and
 //the ringbuffer is locked. Increases write_ptr to the next item. Returns pdTRUE on
 //success, pdFALSE if it can't make the item fit and the calling routine needs to retry
 //later or fail.
 //This function by itself is not threadsafe, always call from within a muxed section.
-static BaseType_t copyItemToRingbuf(ringbuf_t *rb, uint8_t *buffer, size_t buffer_size) 
+static BaseType_t copyItemToRingbufNoSplit(ringbuf_t *rb, uint8_t *buffer, size_t buffer_size) 
 {
-    size_t rbuffer_size=(buffer_size+3)&~3; //Payload length, rounded to next 32-bit value
+    size_t rbuffer_size;
+    rbuffer_size=(buffer_size+3)&~3; //Payload length, rounded to next 32-bit value
+    configASSERT(((int)rb->write_ptr&3)==0); //write_ptr needs to be 32-bit aligned
+    configASSERT(rb->write_ptr-(rb->data+rb->size) >= sizeof(buf_entry_hdr_t)); //need to have at least the size 
+                                            //of a header to the end of the ringbuff
+    size_t rem_len=(rb->data + rb->size) - rb->write_ptr; //length remaining until end of ringbuffer
+    
+    //See if we have enough contiguous space to write the buffer.
+    if (rem_len < rbuffer_size + sizeof(buf_entry_hdr_t)) {
+        //Buffer plus header is not going to fit in the room from wr_pos to the end of the 
+        //ringbuffer... but we're not allowed to split the buffer. We need to fill the 
+        //rest of the ringbuffer with a dummy item so we can place the data at the _start_ of
+        //the ringbuffer..
+        //First, find out if we actually have enough space at the start of the ringbuffer to
+        //make this work (Again, we need 4 bytes extra because otherwise read_ptr==free_ptr)
+        if (rb->free_ptr-rb->data < rbuffer_size+sizeof(buf_entry_hdr_t)+4) {
+            //Will not fit.
+            return pdFALSE;
+        }
+        //If the read buffer hasn't wrapped around yet, there's no way this will work either.
+        if (rb->free_ptr > rb->write_ptr) {
+            //No luck.
+            return pdFALSE;
+        }
+
+        //Okay, it will fit. Mark the rest of the ringbuffer space with a dummy packet.
+        buf_entry_hdr_t *hdr=(buf_entry_hdr_t *)rb->write_ptr;
+        hdr->flags=iflag_dummydata;
+        //Reset the write pointer to the start of the ringbuffer so the code later on can
+        //happily write the data.
+        rb->write_ptr=rb->data;
+    } else {
+        //No special handling needed. Checking if it's gonna fit probably still is a good idea.
+        if (ringbufferFreeMem(rb) < sizeof(buf_entry_hdr_t)+rbuffer_size) {
+            //Buffer is not going to fit, period.
+            return pdFALSE;
+        }
+    }
+
+    //If we are here, the buffer is guaranteed to fit in the space starting at the write pointer.
+    buf_entry_hdr_t *hdr=(buf_entry_hdr_t *)rb->write_ptr;
+    hdr->len=buffer_size;
+    hdr->flags=0;
+    rb->write_ptr+=sizeof(buf_entry_hdr_t);
+    memcpy(rb->write_ptr, buffer, buffer_size);
+    rb->write_ptr+=rbuffer_size;
+
+    //The buffer will wrap around if we don't have room for a header anymore.
+    if ((rb->data+rb->size)-rb->write_ptr < sizeof(buf_entry_hdr_t)) {
+        //'Forward' the write buffer until we are at the start of the ringbuffer.
+        //The read pointer will always be at the start of a full header, which cannot 
+        //exist at the point of the current write pointer, so there's no chance of overtaking
+        //that.
+        rb->write_ptr=rb->data;
+    }
+    return pdTRUE;
+}
+
+//Copies a single item to the ring buffer; allows split items. Assumes there is space in the ringbuffer and
+//the ringbuffer is locked. Increases write_ptr to the next item. Returns pdTRUE on
+//success, pdFALSE if it can't make the item fit and the calling routine needs to retry
+//later or fail.
+//This function by itself is not threadsafe, always call from within a muxed section.
+static BaseType_t copyItemToRingbufAllowSplit(ringbuf_t *rb, uint8_t *buffer, size_t buffer_size) 
+{
+    size_t rbuffer_size;
+    rbuffer_size=(buffer_size+3)&~3; //Payload length, rounded to next 32-bit value
     configASSERT(((int)rb->write_ptr&3)==0); //write_ptr needs to be 32-bit aligned
     configASSERT(rb->write_ptr-(rb->data+rb->size) >= sizeof(buf_entry_hdr_t)); //need to have at least the size 
                                             //of a header to the end of the ringbuff
@@ -92,61 +168,36 @@ static BaseType_t copyItemToRingbuf(ringbuf_t *rb, uint8_t *buffer, size_t buffe
         //that depending on how the ringbuffer is configured.
         //The code here is also expected to check if the buffer, mangled in whatever way is implemented,
         //will still fit, and return pdFALSE if that is not the case.
-        if (rb->flags & flag_allowsplit) {
-            //Buffer plus header is not going to fit in the room from wr_pos to the end of the 
-            //ringbuffer... we need to split the write in two.
-            //First, see if this will fit at all.
-            if (ringbufferFreeMem(rb) < (sizeof(buf_entry_hdr_t)*2)+rbuffer_size) {
-                //Will not fit.
-                return pdFALSE;
-            }
-            //Because the code at the end of the function makes sure we always have 
-            //room for a header, this should never assert.
-            configASSERT(rem_len>=sizeof(buf_entry_hdr_t));
-            //Okay, it should fit. Write everything.
-            //First, place bit of buffer that does fit. Write header first...
-            buf_entry_hdr_t *hdr=(buf_entry_hdr_t *)rb->write_ptr;
-            hdr->flags=0;
-            hdr->len=rem_len-sizeof(buf_entry_hdr_t);
-            rb->write_ptr+=sizeof(buf_entry_hdr_t);
-            rem_len-=sizeof(buf_entry_hdr_t);
-            if (rem_len!=0) {
-                //..then write the data bit that fits.
-                memcpy(rb->write_ptr, buffer, rem_len);
-                //Update vars so the code later on will write the rest of the data.
-                buffer+=rem_len;
-                rbuffer_size-=rem_len;
-                buffer_size-=rem_len;
-            } else {
-                //Huh, only the header fit. Mark as dummy so the receive function doesn't receive
-                //an useless zero-byte packet.
-                hdr->flags|=iflag_dummydata;
-            }
-            rb->write_ptr=rb->data;
+        //Buffer plus header is not going to fit in the room from wr_pos to the end of the 
+        //ringbuffer... we need to split the write in two.
+        //First, see if this will fit at all.
+        if (ringbufferFreeMem(rb) < (sizeof(buf_entry_hdr_t)*2)+rbuffer_size) {
+            //Will not fit.
+            return pdFALSE;
+        }
+         //Because the code at the end of the function makes sure we always have 
+        //room for a header, this should never assert.
+        configASSERT(rem_len>=sizeof(buf_entry_hdr_t));
+         //Okay, it should fit. Write everything.
+        //First, place bit of buffer that does fit. Write header first...
+        buf_entry_hdr_t *hdr=(buf_entry_hdr_t *)rb->write_ptr;
+        hdr->flags=0;
+        hdr->len=rem_len-sizeof(buf_entry_hdr_t);
+        rb->write_ptr+=sizeof(buf_entry_hdr_t);
+        rem_len-=sizeof(buf_entry_hdr_t);
+        if (rem_len!=0) {
+            //..then write the data bit that fits.
+            memcpy(rb->write_ptr, buffer, rem_len);
+            //Update vars so the code later on will write the rest of the data.
+            buffer+=rem_len;
+            rbuffer_size-=rem_len;
+            buffer_size-=rem_len;
         } else {
-            //Buffer plus header is not going to fit in the room from wr_pos to the end of the 
-            //ringbuffer... but we're not allowed to split the buffer. We need to fill the 
-            //rest of the ringbuffer with a dummy item so we can place the data at the _start_ of
-            //the ringbuffer..
-            //First, find out if we actually have enough space at the start of the ringbuffer to
-            //make this work (Again, we need 4 bytes extra because otherwise read_ptr==free_ptr)
-            if (rb->free_ptr-rb->data < rbuffer_size+sizeof(buf_entry_hdr_t)+4) {
-                //Will not fit.
-                return pdFALSE;
-            }
-            //If the read buffer hasn't wrapped around yet, there's no way this will work either.
-            if (rb->free_ptr > rb->write_ptr) {
-                //No luck.
-                return pdFALSE;
-            }
-
-            //Okay, it will fit. Mark the rest of the ringbuffer space with a dummy packet.
-            buf_entry_hdr_t *hdr=(buf_entry_hdr_t *)rb->write_ptr;
-            hdr->flags=iflag_dummydata;
-            //Reset the write pointer to the start of the ringbuffer so the code later on can
-            //happily write the data.
-            rb->write_ptr=rb->data;
+            //Huh, only the header fit. Mark as dummy so the receive function doesn't receive
+            //an useless zero-byte packet.
+            hdr->flags|=iflag_dummydata;
         }
+        rb->write_ptr=rb->data;
     } else {
         //No special handling needed. Checking if it's gonna fit probably still is a good idea.
         if (ringbufferFreeMem(rb) < sizeof(buf_entry_hdr_t)+rbuffer_size) {
@@ -174,9 +225,40 @@ static BaseType_t copyItemToRingbuf(ringbuf_t *rb, uint8_t *buffer, size_t buffe
     return pdTRUE;
 }
 
+
+//Copies a bunch of daya to the ring bytebuffer. Assumes there is space in the ringbuffer and
+//the ringbuffer is locked. Increases write_ptr to the next item. Returns pdTRUE on
+//success, pdFALSE if it can't make the item fit and the calling routine needs to retry
+//later or fail.
+//This function by itself is not threadsafe, always call from within a muxed section.
+static BaseType_t copyItemToRingbufByteBuf(ringbuf_t *rb, uint8_t *buffer, size_t buffer_size) 
+{
+    size_t rem_len=(rb->data + rb->size) - rb->write_ptr; //length remaining until end of ringbuffer
+    
+    //See if we have enough contiguous space to write the buffer.
+    if (rem_len < buffer_size) {
+        //...Nope. Write the data bit that fits.
+        memcpy(rb->write_ptr, buffer, rem_len);
+        //Update vars so the code later on will write the rest of the data.
+        buffer+=rem_len;
+        buffer_size-=rem_len;
+        rb->write_ptr=rb->data;
+    }
+
+    //If we are here, the buffer is guaranteed to fit in the space starting at the write pointer.
+    memcpy(rb->write_ptr, buffer, buffer_size);
+    rb->write_ptr+=buffer_size;
+    //The buffer will wrap around if we're at the end.
+    if ((rb->data+rb->size)==rb->write_ptr) {
+        rb->write_ptr=rb->data;
+    }
+    return pdTRUE;
+}
+
 //Retrieves a pointer to the data of the next item, or NULL if this is not possible.
 //This function by itself is not threadsafe, always call from within a muxed section.
-static uint8_t *getItemFromRingbuf(ringbuf_t *rb, size_t *length)
+//Because we always return one item, this function ignores the wanted_length variable.
+static uint8_t *getItemFromRingbufDefault(ringbuf_t *rb, size_t *length, int wanted_length)
 {
     uint8_t *ret;
     configASSERT(((int)rb->read_ptr&3)==0);
@@ -210,10 +292,48 @@ static uint8_t *getItemFromRingbuf(ringbuf_t *rb, size_t *length)
     return ret;
 }
 
+//Retrieves a pointer to the data in the buffer, or NULL if this is not possible.
+//This function by itself is not threadsafe, always call from within a muxed section.
+//This function honours the wanted_length and will never return more data than this.
+static uint8_t *getItemFromRingbufByteBuf(ringbuf_t *rb, size_t *length, int wanted_length)
+{
+    uint8_t *ret;
+    if (rb->read_ptr != rb->free_ptr) {
+        //This type of ringbuff does not support multiple outstanding buffers.
+        return NULL;
+    }
+    if (rb->read_ptr == rb->write_ptr) {
+        //No data available.
+        return NULL;
+    }
+    ret=rb->read_ptr;
+    if (rb->read_ptr > rb->write_ptr) {
+        //Available data wraps around. Give data until the end of the buffer.
+        *length=rb->size-(rb->read_ptr - rb->data);
+        if (wanted_length != 0 && *length > wanted_length) {
+            *length=wanted_length;
+            rb->read_ptr+=wanted_length;
+        } else {
+            rb->read_ptr=rb->data;
+        }
+    } else {
+        //Return data up to write pointer.
+        *length=rb->write_ptr -rb->read_ptr;
+        if (wanted_length != 0 && *length > wanted_length) {
+            *length=wanted_length;
+            rb->read_ptr+=wanted_length;
+        } else {
+            rb->read_ptr=rb->write_ptr;
+        }
+    }
+    return ret;
+}
+
+
 //Returns an item to the ringbuffer. Will mark the item as free, and will see if the free pointer
 //can be increase.
 //This function by itself is not threadsafe, always call from within a muxed section.
-static void returnItemToRingbuf(ringbuf_t *rb, void *item) {
+static void returnItemToRingbufDefault(ringbuf_t *rb, void *item) {
     uint8_t *data=(uint8_t*)item;
     configASSERT(((int)rb->free_ptr&3)==0);
     configASSERT(data >= rb->data);
@@ -249,6 +369,17 @@ static void returnItemToRingbuf(ringbuf_t *rb, void *item) {
 }
 
 
+//Returns an item to the ringbuffer. Will mark the item as free, and will see if the free pointer
+//can be increase.
+//This function by itself is not threadsafe, always call from within a muxed section.
+static void returnItemToRingbufBytebuf(ringbuf_t *rb, void *item) {
+    uint8_t *data=(uint8_t*)item;
+    configASSERT(data >= rb->data);
+    configASSERT(data < rb->data+rb->size);
+    //Free the read memory.
+    rb->free_ptr=rb->read_ptr;
+}
+
 void xRingbufferPrintInfo(RingbufHandle_t ringbuf)
 {
     ringbuf_t *rb=(ringbuf_t *)ringbuf;
@@ -259,7 +390,7 @@ void xRingbufferPrintInfo(RingbufHandle_t ringbuf)
 
 
 
-RingbufHandle_t xRingbufferCreate(size_t buf_length, BaseType_t allow_split_items)
+RingbufHandle_t xRingbufferCreate(size_t buf_length, ringbuf_type_t type)
 {
     ringbuf_t *rb = malloc(sizeof(ringbuf_t));
     if (rb==NULL) goto err;
@@ -273,9 +404,35 @@ RingbufHandle_t xRingbufferCreate(size_t buf_length, BaseType_t allow_split_item
     rb->free_space_sem = xSemaphoreCreateBinary();
     rb->items_buffered_sem = xSemaphoreCreateBinary();
     rb->flags=0;
-    if (allow_split_items) rb->flags|=flag_allowsplit;
+    if (type==RINGBUF_TYPE_ALLOWSPLIT) {
+        rb->flags|=flag_allowsplit;
+        rb->copyItemToRingbufImpl=copyItemToRingbufAllowSplit;
+        rb->getItemFromRingbufImpl=getItemFromRingbufDefault;
+        rb->returnItemToRingbufImpl=returnItemToRingbufDefault;
+        //Calculate max item size. Worst case, we need to split an item into two, which means two headers of overhead.
+        rb->maxItemSize=rb->size-(sizeof(buf_entry_hdr_t)*2)-4;
+    } else if (type==RINGBUF_TYPE_BYTEBUF) {
+        rb->flags|=flag_bytebuf;
+        rb->copyItemToRingbufImpl=copyItemToRingbufByteBuf;
+        rb->getItemFromRingbufImpl=getItemFromRingbufByteBuf;
+        rb->returnItemToRingbufImpl=returnItemToRingbufBytebuf;
+        //Calculate max item size. We have no headers and can split anywhere -> size is total size minus one.
+        rb->maxItemSize=rb->size-1;
+    } else if (type==RINGBUF_TYPE_NOSPLIT) {
+        rb->copyItemToRingbufImpl=copyItemToRingbufNoSplit;
+        rb->getItemFromRingbufImpl=getItemFromRingbufDefault;
+        rb->returnItemToRingbufImpl=returnItemToRingbufDefault;
+        //Calculate max item size. Worst case, we have the write ptr in such a position that we are lacking four bytes of free
+        //memory to put an item into the rest of the memory. If this happens, we have to dummy-fill
+        //(item_data-4) bytes of buffer, then we only have (size-(item_data-4) bytes left to fill
+        //with the real item. (item size being header+data)
+        rb->maxItemSize=(rb->size/2)-sizeof(buf_entry_hdr_t)-4;
+    } else {
+        configASSERT(0);
+    }
     if (rb->free_space_sem == NULL || rb->items_buffered_sem == NULL) goto err;
     vPortCPUInitializeMutex(&rb->mux);
+
     return (RingbufHandle_t)rb;
 
 err:
@@ -303,18 +460,7 @@ size_t xRingbufferGetMaxItemSize(RingbufHandle_t ringbuf)
 {
     ringbuf_t *rb=(ringbuf_t *)ringbuf;
     configASSERT(rb);
-    //In both cases, we return 4 bytes less than what we actually can have. If the ringbuffer is
-    //indeed entirely filled, read_ptr==free_ptr, which throws off the free space calculation.
-    if (rb->flags & flag_allowsplit) {
-        //Worst case, we need to split an item into two, which means two headers of overhead.
-        return rb->size-(sizeof(buf_entry_hdr_t)*2)-4;
-    } else {
-        //Worst case, we have the write ptr in such a position that we are lacking four bytes of free
-        //memory to put an item into the rest of the memory. If this happens, we have to dummy-fill
-        //(item_data-4) bytes of buffer, then we only have (size-(item_data-4) bytes left to fill
-        //with the real item. (item size being header+data)
-        return (rb->size/2)-sizeof(buf_entry_hdr_t)-4;
-    }
+    return rb->maxItemSize;
 }
 
 BaseType_t xRingbufferSend(RingbufHandle_t ringbuf, void *data, size_t dataSize, TickType_t ticks_to_wait)
@@ -352,7 +498,7 @@ BaseType_t xRingbufferSend(RingbufHandle_t ringbuf, void *data, size_t dataSize,
         portENTER_CRITICAL(&rb->mux);
         //Another thread may have been able to sneak its write first. Check again now we locked the ringbuff, and retry
         //everything if this is the case. Otherwise, we can write and are done.
-        done=copyItemToRingbuf(rb, data, dataSize);
+        done=rb->copyItemToRingbufImpl(rb, data, dataSize);
         portEXIT_CRITICAL(&rb->mux);
     }
     xSemaphoreGive(rb->items_buffered_sem);
@@ -371,7 +517,7 @@ BaseType_t xRingbufferSendFromISR(RingbufHandle_t ringbuf, void *data, size_t da
         //Does not fit in the remaining space in the ringbuffer.
         write_succeeded=pdFALSE;
     } else {
-        write_succeeded = copyItemToRingbuf(rb, data, dataSize);
+        write_succeeded = rb->copyItemToRingbufImpl(rb, data, dataSize);
     }
     portEXIT_CRITICAL_ISR(&rb->mux);
     if (write_succeeded) {
@@ -381,7 +527,7 @@ BaseType_t xRingbufferSendFromISR(RingbufHandle_t ringbuf, void *data, size_t da
 }
 
 
-void *xRingbufferReceive(RingbufHandle_t ringbuf, size_t *item_size, TickType_t ticks_to_wait) 
+static void *xRingbufferReceiveGeneric(RingbufHandle_t ringbuf, size_t *item_size, TickType_t ticks_to_wait, size_t wanted_size) 
 {
     ringbuf_t *rb=(ringbuf_t *)ringbuf;
     uint8_t *itemData;
@@ -398,7 +544,7 @@ void *xRingbufferReceive(RingbufHandle_t ringbuf, size_t *item_size, TickType_t
         }
         //Okay, we seem to have data in the buffer. Grab the mux and copy it out if it's still there.
         portENTER_CRITICAL(&rb->mux);
-        itemData=getItemFromRingbuf(rb, item_size);
+        itemData=rb->getItemFromRingbufImpl(rb, item_size, wanted_size);
         portEXIT_CRITICAL(&rb->mux);
         if (itemData) {
             //We managed to get an item.
@@ -408,6 +554,11 @@ void *xRingbufferReceive(RingbufHandle_t ringbuf, size_t *item_size, TickType_t
     return (void*)itemData;
 }
 
+void *xRingbufferReceive(RingbufHandle_t ringbuf, size_t *item_size, TickType_t ticks_to_wait)
+{
+	return xRingbufferReceiveGeneric(ringbuf, item_size, ticks_to_wait, 0);
+}
+
 
 void *xRingbufferReceiveFromISR(RingbufHandle_t ringbuf, size_t *item_size) 
 {
@@ -415,7 +566,28 @@ void *xRingbufferReceiveFromISR(RingbufHandle_t ringbuf, size_t *item_size)
     uint8_t *itemData;
     configASSERT(rb);
     portENTER_CRITICAL_ISR(&rb->mux);
-    itemData=getItemFromRingbuf(rb, item_size);
+    itemData=rb->getItemFromRingbufImpl(rb, item_size, 0);
+    portEXIT_CRITICAL_ISR(&rb->mux);
+    return (void*)itemData;
+}
+
+void *xRingbufferReceiveUpTo(RingbufHandle_t ringbuf, size_t *item_size, TickType_t ticks_to_wait, size_t wanted_size) {
+    ringbuf_t *rb=(ringbuf_t *)ringbuf;
+	if (wanted_size == 0) return NULL;
+    configASSERT(rb);
+    configASSERT(rb->flags & flag_bytebuf);
+	return xRingbufferReceiveGeneric(ringbuf, item_size, ticks_to_wait, wanted_size);
+}
+
+void *xRingbufferReceiveUpToFromISR(RingbufHandle_t ringbuf, size_t *item_size, size_t wanted_size)
+{
+    ringbuf_t *rb=(ringbuf_t *)ringbuf;
+    uint8_t *itemData;
+	if (wanted_size == 0) return NULL;
+    configASSERT(rb);
+    configASSERT(rb->flags & flag_bytebuf);
+    portENTER_CRITICAL_ISR(&rb->mux);
+    itemData=rb->getItemFromRingbufImpl(rb, item_size, 0);
     portEXIT_CRITICAL_ISR(&rb->mux);
     return (void*)itemData;
 }
@@ -425,7 +597,7 @@ void vRingbufferReturnItem(RingbufHandle_t ringbuf, void *item)
 {
     ringbuf_t *rb=(ringbuf_t *)ringbuf;
     portENTER_CRITICAL_ISR(&rb->mux);
-    returnItemToRingbuf(rb, item);
+    rb->returnItemToRingbufImpl(rb, item);
     portEXIT_CRITICAL_ISR(&rb->mux);
     xSemaphoreGive(rb->free_space_sem);
 }
@@ -435,7 +607,7 @@ void vRingbufferReturnItemFromISR(RingbufHandle_t ringbuf, void *item, BaseType_
 {
     ringbuf_t *rb=(ringbuf_t *)ringbuf;
     portENTER_CRITICAL_ISR(&rb->mux);
-    returnItemToRingbuf(rb, item);
+    rb->returnItemToRingbufImpl(rb, item);
     portEXIT_CRITICAL_ISR(&rb->mux);
     xSemaphoreGiveFromISR(rb->free_space_sem, higher_prio_task_awoken);
 }