I'll note you can choose to either make:

A lightweight plugin that interfaces to a platform-agnostic api that  
requires you to use lots of platform specific C code.

A heavyweight class(es) that manages data and passes data only to a  
plugin which makes the DLL API call, no pre/post C code wrapping api  
call.
or a plugin that abuses self cCode: inSmalltalk: and makes the api  
calls required and has no external C code, except for say a DLL  
library of some sort.

Or of course use FFI.

In some respects exposing the RAW DLL API in a plugin then having a  
heavyweight class drive it is best because any changes to logic can  
mostly be done in smalltalk, otherwise
with a platform agnostic API you get to post and mange change via  
external C code and publish plugins forever...

So for example:

primitiveMPEG3AudioSamples: fileHandle stream: aNumber
	| file result |

	"long mpeg3_audio_samples(mpeg3_t *file, int stream)"
	self var: #file declareC: 'mpeg3_t * file'.
	self primitive: 'primitiveMPEG3AudioSamples'
		parameters: #(Oop SmallInteger).

	file := self mpeg3tValueOf: fileHandle.
	file = nil ifTrue: [^0].
	aNumber < 0 ifTrue: [interpreterProxy success: false. ^nil].
	aNumber >= (self cCode: 'mpeg3_total_astreams(file)') ifTrue: [
		interpreterProxy success: false. ^0.
	].

	self cCode: 'result = mpeg3_audio_samples(file,aNumber)'.
	^result asOop: Float


I could have made the check for file nil, and the check for stream  
part of the smalltalk code that interfaces to the plugin so that I  
would only have
primitiveMPEG3AudioSamples: fileHandle stream: aNumber
	| result |

	"long mpeg3_audio_samples(mpeg3_t *file, int stream)"
	self var: #file declareC: 'mpeg3_t * file'.
	self primitive: 'primitiveMPEG3AudioSamples'
		parameters: #(Oop SmallInteger).
	self cCode: 'result = mpeg3_audio_samples(file,aNumber)'.
	^result asOop: Float

Note we return the samples as a Float to avoid the issue with small  
versus large integers. I guess today we could return a 32bit Integer,  
but I believe those methods was added later when we were working on  
the large file indexing support.

On 1-Nov-05, at 2:01 PM, tim Rowledge wrote:

>
> Wise padawan. Make sure it is nice and clean, use a subclass of  
> SmartSyntaxInterpreterPlugin if possible and little by little you  
> can duck-nibble the problem to death.
>
>

--
======================================================================== 
===
John M. McIntosh <johnmci at smalltalkconsulting.com> 1-800-477-2659
Corporate Smalltalk Consulting Ltd.  http://www.smalltalkconsulting.com
======================================================================== 
===