2014-0816

VERY TEMPORARY

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Today I’m going to talk about some old stuff. Don’t worry though, most of you haven’t seen it yet. A year ago, at our traditional summer meeting, I demoed some very early and experimental CoolBasic builds. The reason I want to show code and screens this old, is so that it’s easier to explain about how things have since changed in the future coming blog posts.

Back in 2013 I actually had a working environment that consisted of a code editor, CoolBasic compiler, and a debugging runtime. You could write CoolBasic code, pass it to the compiler and finally execute it. It couldn’t render game graphics or play sounds, but the very basic text input and output was in place. At that time I focused on code execution rather than game libraries. Control structures, strings, arrays, types, operators, all that kind of stuff. As a result, the demo was probably very boring to watch, but hey, at least it was executing something!

The Compiler

The compiler was naturally the number one priority to get done. In refreshment, it’s written in C#, running on .NET CLR and Mono, and is a standalone console application so it can be called from anywhere. It wasn’t feature complete back then (for example, Select…Case was missing,) but it could handle most control structures and generate the final bytecode.

Compilers aren’t very exciting, though. All you need to know is it’s now faster, more feature-rich, and hasn’t got a function limit.

A VERY TEMPORARY Editor

The VERY TEMPORARY editor

Before you go to the forums and start complaining about how awful it looks, mind the window title. Guess why it’s called “VERY TEMPORARY EDITOR”. The caps are intended. This will *not* be the editor that will ship – don’t worry. I promise.

In short, I just wanted to test a) how easy it is to integrate the compiler into an IDE, and b) could I perhaps use AvalonEdit as the editing control as opposed to the commercial Actipro SyntaxEditor. I’m already quite familiar with the Actipro component (had a chance to use it in a work project) and I know it is the state-of-the-art option, but perhaps that would be a little bit of an overkill for my purposes.

As it turns out, AvalonEdit is just perfect, at least for the starters; I can always upgrade to Actipro later. AvalonEdit offers configurable syntax highlighting out of the box, supports code completion popups, and is generally fairly extendable. Syntax highlighting definition is loaded from an external XML file, and the list of commands provided by the game engine is imported from a special “framework definition file” that I can generate automatically off a compiled executable or DLL (via reflection.)

It was pretty easy to invoke the compiler, have its output written in a textbox, and parse off any errors it would report. All in all, a successful little test editor.

A VERY TEMPORARY Runtime

The VERY TEMPORARY runtime

That’s not a real game engine. It’s actually just a normal WPF application powered by the new Cool VES virtual machine. In fact, the only available commands are Print, Input, and Timer (for benchmarking.) The intention was to establish a simple “console” which would provide basic input and output so that I could test that the virtual machine doesn’t corrupt the virtual stack or leak memory at any point.

For this reason there are some debugging features available. At any time, I can click this cute pause button:

The pause button

This will halt the virtual machine that’s executing the code. While paused, this UI becomes available:

Metadata: symbols

Debug info: metadata

This view lists all functions and variables and their types. Symbol information is needed for a number of reasons. Firstly, the debugger can emit more meaningful call stacks when the functions’ names are known. Secondly, the runtime can perform proper clean-up when returning from a function as it knows which resources are stored in heap.

Bytecode

Debug info: disassembled program

This listing represents the current program in its “disassembled” form. Here I can see that the program was decoded properly and matches with what the compiler spat out.

Managed resources

Debug info: managed resources

Remember how LoadImage would return a handle that you’d then store into a variable for later use? These handles are called “Resources” internally in Cool VES. For more efficient memory management Cool VES keeps a list on what has been loaded. It’s not a real (unmanaged) memory pointer, but a reference to an internal object that also contains metadata of that object.

Interestingly, also strings are managed resources and they, too have handles that are manipulated every time a string is stored in and consumed off the stack.

Call stack and locals

Debug info: virtual stack

If I want to see the low-level state about the executing program, this is the view I’m interested in. I can inspect the values of each variable, for each function within the call stack. This information, of course, would be presented in a more intuitive way in a real debugger.

So that’s how things were a year ago. Nowadays the compiler is pretty much feature complete, and the real code editor is in the works. I also did some engine experiments based on the DirectX10 interface (initially on DX11, but for whatever reason DirectWrite that I use for text rendering isn’t easily usable in it.) More on these topics in future coming posts.

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2012-0728

Branching rules

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Last time I talked about synthesis and IL generation. Currently, half of the statements already write valid byte code. I have now completed the branching infrastructure that I mentioned in my previous blog post, and most conditional structures and loops are now prepared – including the If, While, and Until structures. The For-Next loop and the Select-Case structure are next. But before going there I decided to wrap up a quick summary about branching rules and what they mean in terms of code compilation.

First of all, there’s a mechanic in place that eliminates unreachable code. For example, if you had an If condition that has a constant expression that always evaluates to false, the compiler knows this during compile time and will not write the byte code for that block. Similarly, if you had a While loop that is known to be always true the compiler doesn’t write the byte code for the expression at all. Code elimination also applies to nested code blocks, meaning that everything inside an unreachable code block is ignored when the byte code output is written. Next, let’s look at the specs:

The If structure

  1. The If and ElseIf statements must know the next ElseIf/Else statement in order to branch when the expression is false
  2. The If, ElseIf and Else statements must know the EndIf statement that is associated with the condition chain; The If statement needs it in order to branch when the expression is false, and the ElseIf and Else statements need it in order to issue an unconditional jump to indicate the end of the previous block
  3. The ElseIf and Else statements must add an unconditional jump to the corresponding EndIf statement before any other byte code unless the statement in question is and ElseIf with a constant value expression of false
  4. If the If/ElseIf expression is a constant value, don’t write expression byte code
  5. If any of the If or ElseIf blocks evaluated to a constant expression of true, don’t write byte code for any of the subsequent blocks in the same chain
  6. If an If block or an ElseIf block has a constant expression of false, don’t write its byte code. This includes nested code blocks

In addition to the rules listed above there are some minor tweaks that accomplish cleaner byte code output; I’ve eliminated some branching instructions that are not needed, for example.

The Repeat-Until structure

  1. The Until and Forever statements must know the corresponding Repeat statement in order to branch to the correct location
  2. If the Until statement’s expression is a constant value of true, do nothing
  3. If the Until statement’s expression is a constant value of false, add an unconditional jump
  4. The Forever statement just adds an unconditional jump

The While-EndWhile structure

  1. The While statement needs to know the corresponding EndWhile statement in order to branch when the expression is false
  2. The EndWhile statement needs to know the corresponding While statement in order to issue an unconditional jump
  3. If the While statement’s expression is a constant value of false, don’t write byte code for the expression or code block
  4. If the While statement’s expression is a constant value of true, don’t write the expression’s byte code
  5. The EndWhile statement only adds an unconditional jump to the While statement

Controlling loops

The old “Exit” statement is now renamed as “Break”. It exits the Repeat, While, For, and Foreach loops, and continues execution from after the loop.

Similarly, a new loop control statement has been added. The “Continue” statement continues the encapsulating loop from its next iteration pass, but doesn’t exit the loop unless the associated condition dictates so.

The implementation of these is quite straight-forward; The Break statement needs to know the loop’s ending statement, and the Continue statement needs to know the loop’s starting statement. Both issue an unconditional jump.

I haven’t yet implemented these, and will retain doing so until I get the For-Next structure done. I might write a similar blog post about the For-Next structure and Select-Case structure next time…

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2012-0720

Moving from analysis to synthesis

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Now that I’m on my summer vacation, I’ve had some time to return to the CoolBasic Classic compiler again (after a month or two of slacking, pardon me), and I’m happy to say that the analysis phase of the compilation process is now basically done. After code analysis the compiler has all the information it needs in order to produce the final byte code output. This phase is called “synthesis”, and it executes by recursively iterating through all statements based on their scope. This approach enables the compiler to omit byte code generation for unreachable code blocks such as If/ElseIf/While/Case blocks that have a constant expression that evaluates to false. Moreover, we could have those user-defined Functions and Subs who aren’t used anywhere in code not to be included to the output IL at all. However, it’s important to process all those code blocks fully even though they wouldn’t get written to IL because we want the compiler to validate the entire source code.

Some of the statements are already written into the output byte code stream such as the assignment statement and a Sub call. Similarly to function calls, the compiler inserts any omitted optional parameters and injects any type conversion operators that might be needed. There are still dozens of statement types to process, but all of them should be quite simple to implement. I decided to tackle the If/ElseIf/Else structure next because it requires some branching infrastructure I need to develop first. Once that’s sorted out it’s easy to implement other program flow control statements such as the While and Until loops.

Branching i.e. jumping is an interesting topic on its own because it’s a common key element and therefore needs to be very efficient. Labels are local to their enclosing Function or Sub symbol, and also the Root (the main program) has its own label “scope”. This means that the programmer can have identically named labels as long as they exist in a different “stack fragment”. The Root/Function/Sub symbols encompass a dictionary of labels, and they’re populated already in the parsing phase so that all labels are known during synthesis. The compiler can therefore match forward jumps without expensive scanning. On the other hand, this technique only applies to GoTo statements – many other statement types need to generate some jump targets.

Statements are processed in the natural program flow order during synthesis. For example, an If statement is processed before the corresponding EndIf statement, but the If statement in question still needs to know where the EndIf statement is in order to jump to the proper location if the expression is false. The compiler needs to link all cognate If/ElseIf/Else/EndIf statements together so that they can access the next member in the chain as well as the final EndIf. For branching to work, the compiler stores the byte code pointer of each statement (labels are considered statements as well even though they don’t generate any IL) when they get iterated by the synthesizer. Of course the If statement can’t know the final address of the EndIf statement upon processing because the EndIf doesn’t yet have the calculated offset, i.e. forward jumps cannot be determined fully at this point.

To solve this problem, all jumps (apart from GoTo statements) are cached in a special list that consist of tuples of an IL jump instruction and the target statement. Just before the IL is physically written to a file the compiler simply iterates this list and fills in the correct jump instruction addresses with the calculated code offsets found in the completely processed statements.

We’re quite close from having a working compiler prototype for internal testing 🙂

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2011-0719

Compiler news

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1,900 word wall-of-text incoming…

I returned to CoolBasic project after three months of learning XNA 3D game programming, and have been continuing to develop the CoolBasic Classic compiler for the last two weeks. Although the main focus has been with the compiler I also designed a new look & feel for the web portal, and it’s being reviewed by the rest of the Team. This entry, however, will be all about the compiler and what’s been done recently.

Can it produce byte code yet? Yes, to some extent. The underlying mechanics are in place, but nothing is written to any file yet. Basically, it can process expressions. This includes (but is not limited to) calculating the result value of a constant expression, resolving names (i.e. mapping the identifier names to their declared symbols), function overload resolution, automatic type conversions, and filling in the missing arguments for optional function parameters. A lot of thought has been put to optimize performance here. In fact, all those things mentioned above are done in a single iteration over the postfix presentation of the expression. I had to inspect how the .NET framework internally works with arrays, stacks, lists, and type conversion to make sure my algorithms were efficient enough. I actually ended up writing a few own implementations for those highly specialized cases I needed (where the framework equivalent would allocate memory in an inefficient way or do more work than needed, for example).

I’m about to go technical…

Expression pre-evaluation
Where I left off before my XNA experimentations, was the constant expression pre-evaluation. This is when the actual expression processor needs to be implemented. You first convert the expression into postfix notation and then evaluate it. Naturally constant expressions can contain constant symbols as well, so a circular reference safety check exists. Identifier names are resolved during evaluation because we need to know the data type of each value in order to determine the final data type and the ultimate value in case of a constant expression.

The expression processor is a single method any statement or symbol processor can call. Therefore we don’t know whether the expression is a constant expression or not (i.e. whether its value can be fully pre-calculated). When a symbol is encountered the first time, it will be “processed” (as in a constant symbol’s value needs to be known before it can be used in other expressions). Since the expression processor can be called by a function symbol’s own processor, in order to pre-evaluate optional parameters’ values, a circular reference safety check must exist for functions as well.

The constant symbol and parameter symbol processors simply check whether the result value was a constant and give an error if it isn’t. In addition, before the pre-evaluated value is assigned to a constant symbol or parameter symbol, it’s converted to the destination data type. I had to write my own optimized routines for this because the .NET framework is clearly a bit too slow with anything<-->string. And I learned how much pain in the ass it can be to convert a double value to string (just have a look at dtoa.c to get the idea) – I ended up implementing a much simpler algorithm for that conversion.

Even though constant value expressions are fully pre-calculated, I plan to add an expression simplifier for non-constant expressions as well in the future. It would basically turn expressions like a+b+2*20-c into a+b-c+40. However, this is a very difficult topic that will need much research in terms of grouping and ordering analysis, and I simply don’t want to be held back because of it (even though I have a partial implementation of it in the V3 compiler already). I don’t see it that important at the moment (in order to get this thing out someday I’ll leave it for now).

Name resolution
The expression is processed once token by token. Each encountered identifier is resolved by its name. This process is called name resolution. I have three special resolvers: Type resolver, Symbol resolver, and Overload resolver. The type resolver is called by a symbol processor (each symbol is validated by its own processor). A symbol processor exists for all symbol types. Most symbol processors resolve the associated data type, but some do additional work such as constant symbol processor who calls the expression processor in order to cache the pre-calculated value. The type resolver is the simplest one: since all type symbols must be declared in the root scope we can direct the search to that to begin with, and also only look for symbols classified as Type.

The identifier resolver is a tad more complex. It is told the context symbol and/or scope and whether the search should be locked to that context only or should it also be extended to upper levels if the name is not found immediately (one example of a locked context would be the dot notation path “a.b.c”). Unlocked search is recursive. In CoolBasic Classic, the main program exists in root scope, but it is not the root symbol; the Global symbol is the ultimate root node of the symbol tree, and all imported framework/engine functions such as LoadImage or MoveObject exist there. This means that you can override them by defining your own functions with the same name. The reason we tell the resolver both the context symbol and scope is that, for example, functions’ parameters don’t have scope during optional expression evaluation. In order to access constant symbols defined in the main program’s context, the search needs to get one symbol level up instead of scope level. Furthermore, functions’ local scopes are isolated from the main program (for obvious reasons), and local identifier, a variable or constant, name resolution cannot therefore access the main program’s base scope’s local variables and constants.

The overload resolution is an interesting one. First of all, name resolution has already succeeded on a function group symbol. Yes, we now have an extra container for all functions of the same name. It stores all overloads of that function. All we need to do is to pick the right overload and map the identifier to its symbol. So we pass a snapshot of the calculation stack to the overload resolver, and based on the data types of those values, the most appropriate overload is chosen. This means that you could have two functions of the same name, say Abs (like ‘absolute value’) that takes and returns an integer, and one that takes and returns a float. The compiler would then pick the right one based on the context in the expression, avoiding unnecessary casting and loss of precision due to choosing the wrong one. Should there be more than one equally qualified overload candidates, an error is generated. Should there be no qualified overloads at all, an error is also generated.

Completing expressions
Now what’s really new here is the injection system. It allows the addition of tokens in the middle of the token list without causing “memory move” operations like List.Insert() does (and yet we’re not operating with a linked list here – it’s not efficient enough in .NET, and I want to avoid the memory overhead generated by it). Omitted arguments for those function parameters classified as “optional” are a good example of injected tokens. But the feature also has one other very important use, for we’re also injecting type conversion tokens. This works with intrinsic data types (integer, float and string). Whenever a value of the wrong type is provided, CoolBasic Classic will try to convert the value to the correct destination type. For example, if you provide array indices as floats, they’ll be automatically converted to integers. Similarly, the function overload resolver tells back which values need to be converted and to which intrinsic data type.

We’ll probably be adding explicit type conversion operators to the language at some point as well; we’re just not sure about their naming yet. Just don’t be disappointed if you don’t see them in the first alpha or beta.

Another cool feature I’ve mentioned before is the presence of short-circuit And and Or operators. They are now fully implemented. They’re different from other operators in that while pre-calculation occurs in the same way as processing any binary operator in a postfix calculation stack, they actually produce byte code with conditional jumps instead of a single operator instruction. The hardest part was to infer the offset of the jump because type conversion instructions as well as loading omitted optional parameters to the instructions list occurs all the time (so that the offset cannot be determined during the conversion from infix to postfix). However, I came up with a clever mechanic that allows the reliable offset calculation without having to give up the idea of a single processing pass.

Byte code generation
I mentioned at the start of this blog post that I’m already able to produce byte code that would calculate the expression’s value in real Cool VES environment. A lot of different small parts had to be implemented before this goal was reached, but I think it’s now working quite well. The expression processor, in addition to calculating the result value, generates the full instruction set, including conversion instructions, short-circuit magic, and injected parameters.

One particularly tricky part was to implement dot notation path processing. While simple paths such as “a.b.c” are quite easy to pull off (just lock the name resolution context to the data type of the previous member’s value), it gets a little more complicated when assignment and arrays come in to play. I hate “exceptions to processing rules” so I had to come up with a unified model that just supports normal values, dot fields, dot array fields, and normal arrays. Array variables are always pointers to their actual buffers, but the value indicated by the index (or indices) on top of stack must be read by another instruction. And since context must be locked for the name resolution to succeed, unlike functions, the array field loader instruction cannot occur after argument values (and you cannot access elements not on top of stack which I could’ve done by creating my own custom stack structure, but it’d still be fundamentally wrong thing to do). So for an array access you need two instructions; one before and one after the arguments. Just like how C# and VB.NET compilers do it. It works now. Actually, byte code generated by CoolBasic Classic compiler is VERY similar to Microsoft CIL (Common Intermediate Language) generated by .NET compilers. For example, there’s no single instruction for operator “<=”, but it’s expressed with the combination of cgt, ldc.i4 0 and ceq instead – i.e. “not greater”.

Still few operators lack implementation of pre-evaluation support, but those should be painless to write in no time. One of these is the assignment operator (that again is a bit of a “different” case from the others), but perhaps I’ll get into that in the next blog post. Now this huge central piece is mainly done, the next big goal is to start iterating actual statements like If, While, For etc. Pretty much branching in general.

TL;DR
Expressions are now processed, and refined into real byte code that can execute on Cool VES platform. The next phase would be to process all statements, and with the help of the expression processor, create the final byte code output we can execute!

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2011-0312

Compiler part 1/2 is done

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One another big part of the CoolBasic Classic Compiler is now complete. The CB classic compiler is a standard 2-pass compiler, meaning that it consists of two major sweeps over the code in its transformation from textual representation into a byte code (the binary form is then consumed by the Cool VES runtime and game engine). There’s but one purpose for the first pass; It parses all code lines and creates lists of symbols, like functions and variables. It also picks all tokens that form expressions. Expressions are used in statements such as If, While, and assignment. We chose the 2-pass approach so that, for example, functions don’t need to be declared “above” any statements that use them. The first pass is thus essentially a gathering phase, and that is now complete. The current status is illustrated in the image below:

CoolBasic Classic Compiler - status 3/2011

Green: done
Yellow: in the progress

Personally speaking, writing parsers for 40 different kinds of statements was a little repetitive and mechanical work (yes, we use specialized parsers instead of a state table and stack), but the boring part is now done. I’d say we’re definitely getting somewhere here. There are already 20,431 lines of C# code in 270 files, so the compiler project alone is pretty huge.

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2011-0131

Compiler analysis techniques

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The CoolBasic Classic compiler has progressed again, and this time I’d like to share some interesting new features about its internal architecture. Using C# enables me to do certain things much more easily than the old procedural approach and the Object Oriented design really starts to kick in. The new compiler is highly structural, and it now records much more data about declared symbols, scopes, and execution paths. This also serves as a good foundation for some code analysis techniques. For example, the compiler will emit warnings for variables, types, and functions that are declared but never used, as well as if a variable is used before it has been initialized. Warnings like these will encourage the users to write better and cleaner code.

The original CoolBasic has almost no optimizations regarding the generated byte code. This is now different: Constant value analysis can ignore code branches (such as If/Else) if the condition can be evaluated to True or False at compile time. Thus, redundant code will not even make it to the final compiled program. Also, since we have constant value pre-evaluation, some expressions will be simplified before conversion to byte code. This ought to improve the runtime performance. In addition, thanks to internal scope-specific dictionaries, resolving branch targets does not produce linear search to all recorded labels (user-defined or generated). This should improve compile time performance greatly for large programs.

We’ll see how far we end up going with code analysis in the future… I’d love to collect data such as Cyclomatic Complexity or Number of Executable Statements in order to derive a general Maintainability Index out of the given source code.

Local scoping
All scopes now have their own list of local variables. This means that the user can declare variables in a code block such as If, For, or Case. These variables are allocated when the execution begins in that block and they will cease to exist after the execution exits the scope. Therefore, it is possible to declare several variables that have the same name as long as they aren’t conflicting in an enclosing block. Consider the following example:

Dim a As Integer

If a = 1 Then
    Dim b As Integer = 2
    // Variable 'b' is only visible within this If block.
	
    // You cannot declare variable 'a' here because it is already declared 
    // outside.
EndIf

If a = 1 Then
    Dim b As Integer = 3
    // Variable 'b' is visible within this If block and any child blocks.
    // Variable 'b' is different than the one declared in the previous 
    // If block.
	
    For i As Integer = 1 To 10
        // Variable 'i' is only visible within this For block.
		
        // Varible 'b' is also visible here since it was declared 
        // in an enclosing block.
        b = b + 1
    Next
EndIf

It is also possible to declare scope specific constants in the same way. Upon entering a scope the Runtime will ensure that all of its local variables are initialized with zero. Similarly, local arrays and strings can now be freed upon leaving the scope.

Short-circuit And/Or
We’ll also change the way how the Boolean And and Or operators work. They have become ‘short-circuit’, meaning that if the end result of the Boolean operation can be determined by just evaluating the first (left) operand, then the program will not evaluate the right half at all. Again this will improve runtime performance, but users need to pay close attention to their code if the right side has any function calls that need to be executed regardless of the end result of the Boolean operation. This is easily fixed, though, by storing the right side expression into a temporary variable first.

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2010-1101

Definition file implementation

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Today’s post is a status update to CoolBasic Classic compiler. From the architectural aspect, most entities and interfaces are now implemented. The most notable ones include messages, symbols, keywords, operators, tokens and definition nodes. There are already almost 130 files in the C# project. Also the lexer is now fully operational so the first “major” part is done.

Late yesterday I finished the Cool Framework Definition File importer. What this means is that the compiler can now be made aware of Cool VES symbols such as functions and constants. For example, the constant “PI” is built-in to Cool VES in the same way as “KEY_ESC” or “COLOR_RED” will be in the future. I also tested how overloaded functions import, and that part is covered as well. Overall, the importer should be done now.

What about if the user wants to declare a function or constant of the same name as one already provided by the framework definition? For example, a user-defined function named “LoadObject” (which has the identical fingerprint with the framework version). Which would the program end up invoking? In such situation there’s two options: 1) Report compile error for ambiguous symbol, or 2) Resolve always to the user-defined symbol first. I don’t like the first option because it has the potential to break code if the framework changes (such symbol is added in the future, for instance).

One important thing to know about Name Resolution is that it bubbles up the tree. That is, if no match is found in the current context, query the search in its parent symbol’s context until a match is found or the entire tree has been processed. It never iterates the children of an upper level, though. In CoolBasic Classic the prime scope is the Root – all functions and the main program belong to the Root. In addition, there’s one more scope the Root belongs to, but to which the user has no access. It’s the Global scope, and that’s where the imported symbols go. Thus, Name Resolution will stop at the root level (user code) if the match is found, and will only proceed to the Global context if it wasn’t. Therefore, user-defined symbols will override any identical framework symbols. There’s one thing to note, though. If the signatures don’t match, but the names do, Name Resolution stops at the Root scope and will report possible compile error if no compatible signatures can be found (so it’s still possible for a framework update to break existing code, but only if the user intentionally tries to invoke the framework version).

The image below illustrates the current compiler status. Green boxes are considered “ready”.
CoolBasic Classic compiler status (2010-11-01)

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2010-1027

The ‘Classic’ compiler in C#

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First things first: I’d like to correct the wording in one of my previous post’s statements. I mentioned this “another compiler that didn’t turn out that good”. Some people are now under the impression that C# is to blame for the project in question being now in a frozen state. Maybe I phrased it poorly, but the fact that it was developed in C# at first, has little to do with its failure. The author clarified to me that he dropped C# and switched over to C++ just for the sake of re-writing, and not due to performance issues. Personally, I don’t buy that, but that doesn’t matter. What matters is that a lot of people are paying a lot of attention to what I actually say, and I should be more careful how to express my thoughts in this blog. So let me emphasize once and for all… the other compiler project was ‘successfully’ developed in C#, and later in C++, but is now paused for an undetermined time due to completely unrelated reasons. There. Case closed. He’s watching my blog very closely, though 😉

And then onto other issues at hand. The new compiler (written in C#) is progressing nicely. In the beginning there’s naturally lots of plain setup to do just to get most of the needed entities created. It’ll get more interesting soon, though. For the past week, I’ve used approximately 4 to 6 hours almost every day after work to establish the new compiler solution. That’s a healthy 12-14 hours of programming a day 😉 . Time flows easily when you listen to inspirational music. Currently, the compiler parses the command line arguments, initializes a build job, and invokes the lexer on the source file. Half of all token types are already recognized, and there’s also one dummy parser (which, for testing purposes, only prints all tokens to the console output). I expect to finish the lexical analysis on the remaining token types soon. And then I can start implementing the statement parsers – which ought to be interesting because I now have some new tools at my disposal, thanks to object oriented platform.

I decided to take a little different approach for error reporting. All old compilers shut down the process immediately after encountering the first compile error. This new design doesn’t do that, but the compiler creates a list of compile errors instead and prints them to the standard error stream. This allows Cool Developer editor to compose a neat listing the user can then iterate through and fix more issues at once before re-building. This will probably save time on trial-error, and thus enhance productivity. Basically, this concept requires the compiler to be able to recover from compile errors and simply continue the process from the next statement. Oh, architectural joy! In addition, the compiler now also supports warnings i.e. messages that don’t count as errors, but still hold information about problems in code. Warnings don’t cause the compilation to fail, but they too will be listed in Cool Developer’s user interface.

As a bonus, you’d call the CoolBasic Classic compiler from command line like this (subject to change):

cbccompiler mygame.cbc /out mygame.obj /def coolves.fw

You can optionally enable Finnish interface by adding /lang fi

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2010-0629

Cool (Game) Developer

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The new CoolBasic project is divided into several sub-projects. Each team member has been assigned to one of these projects according to their skills. This first half of the year has proven to be productive, and we actually have concrete results already. Most news has been posted on the Finnish forums, and I apologize to you non Finnish people, although we tend to evaluate things we want to share every once in two weeks, we’ve been quite silent about our plans and doings. The reason there’s been so little information in English is purely that we want to limit how the word spreads at this point in time – we all know what happens to too high expectations in the end. The Beta plan is to first limit it to a smaller closed group which makes possible for us to iron out the most critical bugs. After that we’ll extend the Beta program, ultimately for all. However, please notice that talking about Beta doesn’t mean it exists yet. We’re not there yet. In this blog post I wish to shed some light to the different aspects of the huge CoolBasic project. More details will follow in forth-coming blog posts, this is just a compendium.

Before we start…
At the beginning of June we had a public meeting to which nearly 20 members of the CoolBasic community participated. We rented a summer cabin for a weekend and headed to Nilsiä situated in middle Finland. Many of us saw each other in real life for the first time and had a chance to talk face to face. It was a bit rainy, but I at least wasn’t too sad about it – I think we all had a great time having sauna, barbequing some sausages, playing games, and having fun in general. Too bad it was only 3 days, but arranging the date so that this many were able to make it, isn’t as easy as it sounds. Half of the participants were in fact Devs from the team, and we actually had a presentation, powered by a video projector, to show off the new editor and engine features. More social meetings, please 🙂 There’s definitely going to be another next year!

The CoolBasic Meet 2010

The Editor
The old CoolBasic editor will be completely replaced with a modern project based development environment. This time we’re aiming really high, and this new editor, Cool Developer, is designed so that it can serve as development environment for future coming products as well! It’s highly modular and the architecture makes it possible to develop powerful plug-ins for it. We’ll probably even offer free Visual Studio templates for download so that anyone can develop a new plug-in (or an entire product, perhaps your own programming language) for Cool Developer. The editor is fully customizable and localizable, and it can dynamically load custom made UI modules on the fly. In addition, the way the editor looks, is fully customizable through skinning. I think we’ll go for cool black look this time 🙂 If you know XAML, it’s relatively easy to write your own skins. Skinning the editor, however, is not just defining the colors – it’s possible to compose everything, including layout, UI animations, and visual effects!

CoolBasic games are now created as projects that host all the related code files. Much like in Microsoft Visual Studio, project structure is a hierarchical list of all files associated with that project, including code, media, and other content. Those units don’t necessarily reflect the underlying file system at all, but the entire project is easily transferred between different machines by simply copying a single folder. You can also have several projects open at the same time, in which case the top-most element within the hirearchy is a “Solution File”. it’s basically a collection of different projects. Imagine you have a game (solution) that includes a CoolBasic Classic code project, and a Tilester project that has all the maps the game uses.

We’ll also construct a new “Start Page” that will list the most recently accessed projects, show you some news from the CoolBasic community, and perhaps feature some interactive content. It might even be possible for you users to customize the start page via XAML.

Everything, including the Start Page, manual, code files, and visual editors, can be opened into a tab. The behavior is much like in the current (obsolete) editor, only there’s no limit what you can open in a tab. We can even present complex editors, such as a tilemap designer, inside the editor now. Imagine a visual editor to build game objects, or a tool that packs game media in a compressed file! We basically associate some content presenter to a file type: for code files it’s going to be a syntax highlighter editor, for other types it’s going to be something else – a web browser for web pages, for example.

The editor also has a built-in update engine which keeps all installed products always up-to-date; you no longer have to manually download and install updates when we fix bugs or add new features to CoolBasic Classic compiler or the CoolVES engine.

As for the user interface, it resembles Visual Studio a bit, but we’d like to enhance it with some fresh ideas. It’s relatively rare, for example, a code editor to have a ribbon… or how about something completely different to the standard Solution Explorer + Property Window combination? A screenshot of the new editor will be provided later – there are a few things we’re experimenting at the moment. At this point, however, it’s looking really cool in its black theme! As a side note, the editor is currently developed by two professional WPF (Windows Presentation Foundation) programmers. And yeah, it’s in .NET Framework 4.0 🙂

Compiler & Language
Although we plan to design the language as similar to the old CoolBasic as possible, we’re going to make some changes to the basic syntax to accommodate “more accustomed” practices. For example the member access operator “” is going to be replaced with a dot. Custom typed variables are declared via the “As” clause inside a “Dim” statement. Arrays and Linked Lists will also see major improvements – it’s now possible to pass arrays as arguments, and return arrays from functions. Arrays can also be of any (custom) type. Linked Lists are no longer singletons based on a type i.e. you can create as many Linked Lists of any type as you like. There’s also going to be differentiation of Subs and Functions. We may also enhance the “If” statement chain. Structured error handling and a debugger are also considered. Of course, we’ll integrate the debugger to Cool Developer editor as well. All in all, most old CoolBasic games should be relatively easy to port and compile against the new execution engine. Simple find&replace throughout legacy code will probably not be enough, but the additional adjustments one would have to make manually are merely trivial.

CoolBasic Classic is producing CoolVES compliant byte code. This means that the game engine is separate to the language that simply is porting games for its use i.e. it might be possible to write CoolVES games in other languages than a BASIC in the future! Or having a completely visual game building tool (like Click’n’Play / Game Maker) for the CoolVES engine! Maybe CoolBasic Classic could even operate as the programming language for other execution engines as well *cough*.

The improvements to the current CoolBasic Classic compiler (taken from experimental code of the V3 compiler) have proven to be working well. The lexer and parser are already done, and code analysis is under construction. It won’t take long until I get to the synthesis part which essentially means, at that point, the compiler can actually produce byte code and the development of the CoolVES execution system can begin! That’s also when the cool stuff begins and the rest of our team members get their hands on some really nice stuff. Perhaps a public tech demo will follow 🙂

The Game Engine
Now the actual game engine is something that has made huge progress during the past few months. It’s going to be OpenGL based and cross-platform. Whereas the old CoolBasic only has software renderer, the new graphics engine is taking full advantage of modern hardware. The engine is already able to render game objects on to screen, and rotate, scale and transform them – basically everything one can already do in old CoolBasic. Blending with different modes is supported as well as different filtering methods. We’re even experimenting with some more complex materials. The game objects can now also have a parent so that they move, rotate and scale in relative to the parent object. In addition, we now have multiple camera support, and camera zoom and rotation! It’s probably a bit too early to talk about object animations, but we do have major plans to drastically improve it. Also tilemaps are going to go through lots of improvements in terms of rendering, interacting and collision checking. All in all, there’s a lot more you can do with game objects now, and the command sets are going to be re-designed from scratch.

As what comes to the audio system, we’re dumping integrated FMOD. It may become an option again later in the future (optional engine you could enable for use in the project settings within Cool Developer interface). FMOD makes it possible to use wide variety of different formats, and even visualize the output stream, but for now we’re going to implement the Audiere library which is completely royalty free for commercial and noncommercial use. As a side note, the primary recommended format all CoolBasic demos and tutorials will use, is going to be MP3.

Perhaps one of the most interesting new major features we’re adding, is the in-built game physics. Every game object can have full 2D dynamics applied to them. You’ll simply define mass and shape (amongst a few other attributes) for an object, and everything else is done automatically for you – objects will bounce accordingly from walls and each other. Implementing this powerful feature will enable the users to create games like never seen before in CoolBasic! This system also serves as base to in-game collisions, to make game character jump you only need to apply an impulse upwards. Should you hit your head to the ceiling, you simply drop down again, and automatically stop falling upon hitting the ground. Collision events can be queried; making it possible to fire certain animations in certain situations (crouch upon landing, for example). The physics naturally also apply to particles on screen. You can build more complex physics bodies by combining several existing bodies and you can create constraints to bind separate parts to each other. Perhaps a visual game object building tool for Cool Developer editor will be written at some point.

There are already fully working internal tech demos for the graphics engine and physics. No screenshots for now (as those demos in question render lots of test data on screen).

The Manual
We haven’t formulated full details yet, but a graphical design plan document already exists. As with the V3 manual, we probably won’t be implementing such deep tree view based document structure, but more like a mixture of old design and easier navigation through document pages. We have a few professional web designers in the team, so this time there’s going to be a lot more look and feel to it. While the manual will be written in both English and Finnish, in addition to comprehensive language and framework references, we’re going to focus more on complete tutorials and examples and even in social media and interactive content in general. You will be able to comment the pages, as well. Integrating the manual to Cool Developer so that the two work seamlessly together (in an attempt to provide studying material like never seen before anywhere else) is also one of our top priorities. We have some exciting technologies in mind on how to provide the best manual possible.

The Website
We’re aiming for strong user community. Integrating with the forums and blogs require custom code, and we’re currently building our own CMS (Content Management System) on the CodeIgniter framework. The amount of content we have planned for the new coming website is huge, so its management requires a CMS. It’s a bit too early to provide any screenshots, but the goal is to make the website such a place the users want to visit it in addition to just reading the forums.

Closing words
The information provided by this blog entry was intended to be a general peek of what different sub-projects are involved and what’s their current status. We’ll get back to details later. I hope this delivered some idea of how big of a project the new Cool Game Developing Environment really is. It’s not just CoolBasic Classic, but rather a whole base and framework for future work as well. We have regular internal meetings every other week, after which we normally decide what information we choose to share publically. Sorry for the long wait since the previous blog post, stay tuned.

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2010-0125

CoolBasic Classic DevTeam is up!

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Yeah! Over 2 months in the making, all necessary arrangements are finally done to bring the development team up and running. During this period I’ve been documenting, and documenting, and.. umm.. documenting some more. Less time coding, I know, but it’s better to have well thought-out plans before we start implementing anything. The biggest time-sink has been writing down most of my ideas for CoolBasic Classic so that every member of the DevTeam is aware of and understands them. For now, I think there’s about 200 pages of text if printed. The management has decided to let the newly selected members to have some time reading the important contents from the hidden forum and from the document storage before assigning the first tasks to everyone. We’ll be having our first welcome meeting soon, too. I was happy to see both technical and design-related discussion about various topics within the same evening I promoted the members. I look forward to have rich brainstorming for the few future-coming weeks, too.

I and the managers interviewed all applicants. These sessions were about 45 to 50 minutes long discussions where the candidates were tested against their applications, and their motivation, skills and suitability were evaluated. Those chosen, I believe have true interest in developing this remake of the current, oldish CoolBasic, called CoolBasic Classic. Generally speaking, all interviews were pulled off during one week. There were 4 to 7 interviews per day, and they took place after normal business hours. It was exhausting for me to tailor the questions and the frame for each interview separately (in addition to executing the actual interviews), but I think we did a very good job at it. Having chosen managers beforehand definitely helped, and I’ve had support from them in many aspects how to organize the team efficiently – among other things, we now have an SVN in the works.

Every member was promoted to the Dev forum group, and they now gain access to the hidden development forums. The devs can be recognized from their bright yellow name color. They also received a @coolbasic.com email address as well as the login credentials to the internal website wherein the document storage is found, too. Tech Developers also get a free PureBasic license for 12 months. We ended up to 12 members + management, and I feel that we have a good team that has expertise from various areas of IT. The reviewed organization chart looks like this:

Now that the launch is behind, I can continue my work on the CoolBasic Classic compiler. It’s top priority because we cannot really start with the CoolVES engine until we have some byte code to feed in. Soon there will be various other “projects” launching in parallel, including code editor, internal DevTeam web services and experimental code for CoolVES. In a nutshell, all team members (apart from music artists) should soon have something to work on. Also, we have code quality checks, regular development meetings and branching. Once the compiler is at a certain state, I’ll start writing its technical documentation (internal) along with a public byte code documentation for CoolVES. Yay, I so love documenting *cough*. Right now I’m working on function overload resolution and optional parameter fill-in. When that is completed, only statement-specific validators remain for Pass#2. And when Pass#2 is finished, it’s time to implement the actual byte code synthesis (at that point, I will start specifying its exact command set). The compiler is already lexing and parsing all language features.

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