Loading sibling cods using CodeModuleManager

I recently had occasion to use the CodeModuleManager to load a module onto the BlackBerry after downloading it from a remote server. This was a bit tricky because the javadocs from RIM about CodeModuleManager are at best misleading.

The Javadocs (from 4.7) say:

How to add sibling .cod files.

You need to write the data in two seperate chunks. The first data chunk must be less thank 64KB in size.

1. To write the first data chunk, invoke createNewModule( int totalLength, byte[] data, int length ).
2. To write the second data chunk, invoke writeNewModule( int newModuleHandle, byte[] data, int newModuleOffset, int length ).

First of all, the writeNewModule method metioned is deprecated! But that’s not the worst problem - I’ll explain.

If we have an application with 3 sibling cods, with a total size of say 150000 bytes, you might think (as I did) that the above docs imply that you need to do something like this:

	private void writeModule(byte[] cod1, byte[] cod2, byte[] cod3) {
		int handle = CodeModuleManager.createNewModule(150000, cod1, cod1.length);
		boolean result = CodeModuleManager.writeNewModule(handle, cod1.length, cod2, 0, cod2.length);
		result = CodeModuleManager.writeNewModule(handle, cod1.length + cod2.length, cod3, 0, cod3.length);
		CodeModuleManager.saveNewModule(handle);
	}

You would be wrong! The actual way to do it is:

	private void writeModule(byte[] cod1, byte[] cod2, byte[] cod3) {
		int handle1 = CodeModuleManager.createNewModule(cod1.length, cod1, cod1.length);
		CodeModuleManager.saveNewModule(handle1);
		int handle2 = CodeModuleManager.createNewModule(cod2.length, cod2, cod2.length);
		CodeModuleManager.saveNewModule(handle2);
		int handle3 = CodeModuleManager.createNewModule(cod3.length, cod3, cod3.length);
		CodeModuleManager.saveNewModule(handle3);
	}

The BlackBerry OS knows enough to put the sibling cods together into the same module.

So the above Javadocs are wrong - you only need to write the data in two separate chunks, for an individual sibling cod file, if that cod file is bigger than 64kb. So actually the above code sample will work only if your sibling cods are each less than 64kb. If one of them is more you’ll need to do this:

		int handle1 = CodeModuleManager.createNewModule(cod1.length, cod1, 64000);
		CodeModuleManager.writeNewModule(handle1, 64000, cod1, 64000, cod1.length-64000);
		CodeModuleManager.saveNewModule(handle1);

Of course, only if cod1.length > 64k (I just used 64000 here to be on the safe side - you could actually use 65536 (or maybe 65535?)