[Pharo-project] Questions of understanding

Friedrich Dominicus frido at q-software-solutions.de
Wed May 25 17:30:14 CEST 2011

Mariano Martinez Peck <marianopeck at gmail.com> writes:

> I have no idea. Maybe someone in the VM mailing list can help you.
Ok I  finally got the serialPort access under Cog VM and Linux
I concede it is currently a hackerish solution a combination out of
Squeak sources and Cog sources with a good mixture of Cog 

So whomever may be "reponsible" can get in touch with me and I'll try to
work out a stable implementation on Linux.

But I think there are a few problems with Pharo 1.3 and Cog. AFAIKT one
needs AbstractLauncher. I shamlessly stole it from Squeak. If I do
not have it and start my generated CogVM I just get an open window with
some black rectangle  in the upper left.
This problem was  mentioned at:


Now what did I have to do?
I downloaded the sources from squeak-vm and Cog and there are at least
two different C files and probably a header files with the prototyps:
The two files are 
sqUnixSerial.c which is in  platforms/unix/plugins/SerialPlugin
SerialPlugin in src/plugins/SerialPlugin

It seems the first is the handwritten C-code 

The first is needed to "offer" the functionality and the later is
probabl seems t be the interface to Squeak. I guess this is generated
code from some Slang code which looks like this:

parityType dataBits: dataBits inFlowControlType: inFlowControl outFlowControlType: outFlowControl xOnByte: xOnChar xOffByte: xOffChar

	| cString |
	self primitive: 'primitiveSerialPortOpenByName'
		parameters: #(ByteArray SmallInteger SmallInteger SmallInteger SmallInteger SmallInteger SmallInteger SmallInteger SmallInteger ).
	self var: #cString type: 'char *'.
	cString := self allocateTerminatedString: deviceName.
	self cCode: 'serialPortOpenByName(
			cString, baudRate, stopBitsType, parityType, dataBits,
			inFlowControl, outFlowControl, xOnChar, xOffChar)'

which then write out the proper C code for that plugin. 

You see I'm still ignorant on how this is all supposed to work. 

Nevertheless copying the files at the proper places in the src and
platform tree. This codes get's compiled into the VirtualMachine. 

And I can use this "machine" for accessing the serial interfaces, (it
even works for '/dev/ttyUSBx' devices. For me this is a great thing
because I'm forced to access some periperal devices via serial lines.

I need some extra hack in the generated file (I know this is "dirty" a
missing #define was introduced. I bet there is a better place for that
but in genrated code. But well it's  just an intermediate step. 

If someone here may be interested just drop me a mail and with some help
we'll be able to modify the Cog sources cleanly to use this modified
Plugin for intefacing to serial lines in Linux.

I'm also quite aware that the Smalltalk side of the code could need a
little attention: It looks like:

nextPutAll: aStringOrByteArray 
	"Send the given bytes out this serial port. The port must be
	open. "
	^ port isString
		ifTrue: [self
		primWritePortByName: port
		from: aStringOrByteArray
		startingAt: 1
		count: aStringOrByteArray size]
		ifFalse: [self
		primWritePort: port
		from: aStringOrByteArray
		startingAt: 1
		count: aStringOrByteArray size]

Which is kind of "unproper" IMHO....


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