diff --git a/doc/extensions_funcref.txt b/doc/extensions_funcref.txt
index 0c1a8e3..01c0a02 100644
--- a/doc/extensions_funcref.txt
+++ b/doc/extensions_funcref.txt
@@ -66,6 +66,25 @@ Description:
Returns:
0 on success, -1 on error.
+Function: comedi_get_hardware_buffer_size -- get size of subdevice's hardware buffer
+Retval: int
+Param: comedi_t *device
+Param: unsigned int subdevice
+Param: enum comedi_io_direction direction
+Description:
+ This functions returns the number of bytes the subdevice can hold in it's hardware buffer.
+ The term "hardware buffer" refers to any fifos, etc. on the acquisition board itself which
+ are used during streaming commands. This does not include the buffer maintained by
+ the comedi kernel module in host memory, whose size may be queried by
+ comedi_get_buffer_size.
+ The direction parameter of type
+ enum comedi_io_direction
+ should be set to COMEDI_INPUT to query the input buffer size (e.g., the buffer of an analog
+ input subdevice), or COMEDI_OUTPUT to query the output buffer size (e.g., the buffer of
+ an analog output).
+Returns:
+ Number of bytes, or -1 on error.
+
Function: comedi_get_routing -- get routing for an output
Retval: int
Param: comedi_t * device
diff --git a/doc/reference.xml b/doc/reference.xml
index dcbc670..d12aaeb 100644
--- a/doc/reference.xml
+++ b/doc/reference.xml
@@ -153,6 +153,30 @@ and converting from a physical value to Comedi's integer sample values (COMEDI_F
+
+
+enum comedi_io_direction
+
+
+
+
+enum comedi_io_direction
+{
+ COMEDI_INPUT,
+ COMEDI_OUTPUT
+};
+
+
+
+A comedi_io_direction is used to select between input or output. For example,
+comedi_dio_config
+uses the COMEDI_INPUT and COMEDI_OUTPUT values to specify
+whether a configurable digital i/o channel should be configured as an input
+or output.
+
+
+
+
enum comedi_subdevice_type