This directory contains files for building a Ruby extension library
for Comedi.
Instructions for building by hand (you shouldn't need to do this):
1. Type 'ruby setup.rb config'. This configures for the local
environment.
2. Type 'ruby setup.rb setup'. This builds the extension library.
3. Type 'ruby setup.rb install'. This installs the extension
library and the file lib/comedi.rb, which provides more
Ruby-like method syntax.
The file 'lib/comedi.rb' provides syntactic sugar in three forms:
1. Method names without the 'comedi_' prefix. The Comedi module
disambiguates the namespace. For example, you can say
'dev = Comedi::open()' instead of 'dev = Comedi::comedi_open()'.
2. Instance methods that take an explicit receiver instead of
expecting the target object as an initial argument. For example:
'comedi_close(dev)' can be written as 'dev.close'.
3. A pre-defined IO object and an accessor method to simplify
reading from the file descriptor associated with the comedi device.
Data from comedi device 'dev' can be read by 'dev.ios.read'.
The file 'demo/cmd' is a straight port of 'cmd.c' from the
Comedilib 'demo' directory. It illustrates the basics of programming
Comedi commands using Ruby.
If a Comedilib function returns a value through a pointer passed as an
input parameter, its Ruby counterpart returns the value as an element
of an Array.
ret, cmd = dev.command_test(cmd)
Because the command object is used by command_test() it appears as an
input parameter as well. If the pointer is used only for output, it is
omitted from the parameter list. For example:
data = dev.data_read(subdevice, channel, range, aref);
Steven Jenkins
steven.jenkins@ieee.org
2004-01-12
