What, specifically, are you trying to find out?
The HDL is extremely simple and limited. All you really need to know can be gleaned by the Xor example in Chapter 2. The syntax and semantics are presented in Appendix A of 1ed and Appendix 2 of 2ed.
Here's my attempt at the grammar. This is being written on the fly, so I can't guarantee that it is correct or complete.
There are three comment styles that are supported: Block. End-of-Line (EOL), and API
/* Block comments can span multiple lines */
// EOL comments end at the end of the current line
/** API comments are special block comments that are used by some automated documentation tools */
The basic structure is:
CHIP <ChipName>
{
<ChipInterface>
<ChipImplementation>
}
The ChipInterface consists of the following:
IN: <PinList>;
OUT: <PinList>;
The PinList is a simple list of pin names
<PinName>[, <PinName>]*
I'm not sure of an empty PinList is allowed or not and, similarly, whether both IN and OUT lists must always be present (i.e., if a PinList for one is empty, is that line in the ChipInterface simply excluded). There is a built-in parts for which this is relevant, namely Keyboard.
The ChipImplementation is either a call invoking a built-in Java module, or a description of the interconnection between other parts.
<BuiltInImplementation> | <PartsImplementation>
The BuiltInImplementation is a simple call to the class:
BUILTIN <ChipName>
The ChipName is the same as in the Interface section. I don't know if it is legal to call a different chip (which might be useful to create an alias).
The PartsImplementation is a list of other chips and their connections:
PARTS:
<Part>*
The Part is similarly simple:
<PartName>(<ConnectionList>);
The ConnectionList is a list of pin-to-wire assignments:
<Connection>[,Connection]*
Again, not sure of an empty connection list is allowed, but it would render the part useless.
A connection is merely a single pin-to-wire assignment:
<PinName>=<WireName>
Locked
