Octoate's News - CPCtelera v1.4 – Amstrad CPC game engine for C developers

[NewsBot]

CPCtelera v1.4 – Amstrad CPC game engine for C developers
20 April 2016, 11:30 pm

A new version of CPCtelera, the Amstrad CPC game engine for C developers, was just released in version 1.4. CPCtelera offers a huge C library for the SDCC C cross-compiler, which makes it easier to create games and applications for the Amstrad CPC. This version features a new license (LGPL), support for the CPCRSLib, a lot of new examples and a huge load of new methods and optimisations (see the changelist below). It is available for Windows, Linux and OS-X. You can get the latest version from GitHub and discuss it in the CPCWiki forums.

Changes in v1.4:

• Low-level library, scripts, building system and examples moved to LGPL license to suit more developer needs.
• Added CPCRSLib installer script (cpct_installrslib): automatically installs and configures CPCRSLib to be used along with CPCtelera.
• Added -c modifier to cpct_mkproject to let the user create CPCRSLib enabled projects.
• Improved cpct_drawSpriteMaskedAlignedTable to work with un-aligned sprites. Only 256-bytes transparency table shall be aligned now.
• Added interrupt unsafe functions for keyboard scanning
• Improved img2cpc sprite generation: explicit array width*height sizes and automatic size constants generation.
• Added new high-quality random number generators: Marsaglia XORShift 8/16/32 bits and Marsaglia XORShitf+ 40 bits state.
• Simplified use of random number generators with standard macros cpct_rand and cpct_srand, to work like C functions rand/srand.
• Added simple user example for random number generation: easy/random.
• Added macro IMG2SPRITES for automatically converting tilemap TMX files into C arrays on typing “make”.
• Added macro TMX2C for automatically converting image files into sprites (C-arrays), tiles and tilesets on typing “make”.
• Added configuration files image_conversion.mk and tilemap_conversion.mk to easily include TMX2C and IMG2SPRITES macros for all user assets in the project.
• Added new conversion options to cpct_tmx2csv: generation of C/H files, different output folder, and custom c-identifier generation.
• Added new macros cpctm_createTramsparentMaskTable and cpctm_declareMaskTable to easily define and create 256-bytes aligned transparency tables, greatly simplifying the process.
• Added Horizontal Sprite flipping functions: for Modes 0, 1 & 2 and normal/masked sprites, working from RAM and ROM, to suit different user needs.
• Added user examples for horizontal flipping functions. C-examples: flipAnimM2, flipSprites. ASM-examples: hflipSpriteM1, flipMaskSprite.
• Added macro cpctm_screenPtr to do static calculation of screen memory pointers, saving CPU and binary space when calculating constant locations.
• Updated old examples to use new macros, especially cpctm_screenPtr.
• Improved cpct_img2tileset output messages and success status check. Also added an option to output harware converted palette values.
• Added CPCT_VMEM_START macro defining video memory start: standarizes its uses.
• Updated hello world template example to use new macros, simplifying its code.
• Added assembly macros for undocumented Z80 opcodes: used to clarify code.
• Added ultra-optimized assembly macros for bit and pixel reversing inside bytes: they can reverse pixels inside a byte for modes 0, 1 and 2.
• Added macros CPCT_ABSOLUTE_LOCATION_AREA and CPCT_RELOCATABLE_AREA to absolutely locate code and data inside binary space and memory.
• Added example advanced/relocateMemory to show how to use memory relocation macros.
• Added CPCT_XBITARRAY and CPCT_ENCODEXBITS macros to easily define, declare and populate bitarrays.
• Added new type of bitarrays: bitarrays of 6-bits per item.
• Added new example medium/bitarrayMaps1 to clarify the use of bitarrays as tilemaps and other structures.
• Added sprite blending functions: can blend sprites with background using different modes like XOR, OR, AND, ADD, ADC, SUB, SBC, LDI, NOP.
• Added sprite blending example medium/blendedSprites.
• Added colour enumerations to simplify palette definitions and palete colour changes (CPCT_FW_Colour and CPCT_HW_Colour)
• Added support for cpct_winape script to automatically load debugging symbols on launching DSKs.
• Updated cpct_winape to download Winape 2.0 beta 2.
• Added another ASM example with some sprite/text drawing, automatic sprite conversions and animations.
• Some performance improvements on previous functions.
• Updated to SDCC 3.5.5. (and fixed libboost 1.6. compilation problem).
• Fixed a problem with multithreaded compilation on ARM platforms using SD Cards as main storages (mainly Raspberry Pi)
• Added OBJS2CLEAN variable to makefiles to let the user clean some custom generated objects.
• Improved documentation
• Fixed cpct_tmx2csv failing on cygwin
• Added tilemap_hwscroll example to show hardware scrolling capabilities along with an expanded tilemap.
• Added latest 1.1.1. version of Retro Game Asset Studio (RGAS)
• Everything packed with love to give user the best possible set of tools

© Octoate for The Amstrad CPC news portal, 2016. | Permalink | No comment | Add to del.icio.us  Post tags: 2016, cpcrslib, cpctelera, cross-development, development, engine, framework, game, github, sdcc

 Related posts:

• CPCtelera v1.3 – Amstrad CPC game engine for C developers
• CPCtelera v1.2 / v1.2.1 – Amstrad CPC game engine for C developers
• CPCtelera v1.1 – Amstrad CPC game engine for C developers

Source: The Amstrad CPC news portal

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[EgoTrip]

Just a small update then?

Thanks for this.

[AMSDOS]

The mind still boggles 

[Shining]

I thought about using CPCtelera (or parts) in a later CPC-Project. But neither the GPL-Licence than the LGPL will suit my needs, so I will not be able/allowed to use this great library.


If I code a game, demo or tool for CPC, I do not want to always release source code. So GPL is a no go here.


Under LGPL I have to code my production in a manner that the end-user can link CPCtelera to my game always by himself. Also with a new version of CPCtelera. This is not achievable, when you only want to release the game itself.

Essentially, if it is a "work that uses the library", then it must be possible for the software to be linked with a newer version of the LGPL-covered program. The most commonly used method for doing so is to use "a suitable [/size]shared library[/size] mechanism for linking". Alternatively, a [/size]statically linked library[/size] is allowed if either source code or linkable object files are provided.

(LGPL Chapter 4)


Why don't you use for example the MIT-licence ?

[TotO]

I thought about using CPCtelera (or parts) in a later CPC-Project. But neither the GPL-Licence than the LGPL will suit my needs, so I will not be able/allowed to use this great library.
If I code a game, demo or tool for CPC, I do not want to always release source code. So GPL is a no go here.

What is secret into a CPC game code using a game library? 
At worst, if you produce something more or less interresting, peoples just have to disassemble your binary to know...

The library creator use his free time to offer it, so the respect when you use it is to do the same.
Last but not less, R-Type use its own ASM engine/routines and the source code is free to use and learn with it.

[reidrac]

In my humble opinion the cpctelera is not a game engine, is more like a low-level functions library. Or at least is not a game engine in the same sense "la churrera" is one.

I don't mind the GPL license, I think it could really help the CPC community to thrive by openly sharing code; but for 8-bit retro machines... the GPL isn't great because it makes distribution quite tricky if you want to make a physical release. Besides I'm not sure how well people understand the licence, or at least we can see releases of cpctelera based games being distributed without the source code.

There's another thread about this (Best license for retro software projects?). Of course you may choose to not comply with the library; but if cpctelera wants wide adoption a licence like MIT or even BSD has proven to be perfect for that. Would LGPL be OK? Yes, definitely (may need an static linking exception); although the chances of anyone making changes to a library like this one and then @ronaldo not being able to reproduce them are quite slim.

Honestly, people will contribute to the library if they want to, not because there's a legal requirement. cpcrslib is MIT licensed and I contributed some changes (because I rather let the maintainer maintain those for me).

In a community were we all download and play old games without caring too much about copyright; how much value the GPL adds?

Anyway, I really hope @ronaldo keeps up with the awesome work he is doing. At the moment I'm having a lot of fun learning and writing my own crappy code, so the cpctelera is not quite the tool for me, but it is great resource for anyone that doesn't like going that low level.

[Shining]

What is secret into a CPC game code using a game library? 
At worst, if you produce something more or less interresting, peoples just have to disassemble your binary to know...

The library creator use his free time to offer it, so the respect when you use it is to do the same.
Last but not less, R-Type use its own ASM engine/routines and the source code is free to use and learn with it.

I don't want to start a licence war or something like that.


But if someone decides for watever reason not to release his own source and abides to the provided licence, I do not know how to achieve that.


About releasing source: In general, I have no problem releasing source code of something I did but I have special demands, when I do so. For example the code has to be well commented and it has to be easy understandable for others. On CPC productions, because of its limits, I throw some of my usual own demands overboard to achieve faster code (loop unrolling, inline code, etc.) and then it sometimes looks like spaghetti code but its faster or more suitable for CPC. Without comment or cleaning this up, I don't want to see such code in the net....
(We are still speaking about C-Code, so by dissasembling you will see what it does but not how it looked like)


Again, I don't want to start a dispute here, I'm really thankful for everyone doing stuff for and on CPC. Also, what I've seen until now CPCtelera will be very interesting for me in the future, so I asked how to deal with the licence.

[TotO]

No problem, I understand your point of view.
By the way, a good source code comment increase the productivity and the project sustainability. 

[Munchausen]

The solution is to release CPCtelera under the GPL (or LGPL) with an exception like that for gcc, that allows the inclusion of code in the run time library (without requirements for update capability etc). See: GCC Runtime Library Exception - GNU Project - Free Software Foundation

The issue with MIT, I presume, is that it doesn't prevent someone from selling or distributing CPCtelera without including the source code. Which is fair enough. However I think that it is true that as it stands with GPL/LGPL licensing (and because of the way executables work on a CPC) anything you produce with CPCtelera currently will have to be released with source code under a GPL compatible license.

[ronaldo]

@Munchausen, @TotO, @reidrac, @Shining please, let me clarify terms and reasons for you.

The change from GPL to LGPL is precisely to let people distribute games or software developed using CPCtelera low-level library without having to distribute source code. Chapter 4, referred by @Shining says that "...it must be possible for the software to be linked with a newer version of the LGPL-covered program.". This does not imply distribution of source code, but object code. The only requirement is the possiblity to link again with a new version of CPCtelera low-library, not to compile again from source. And, distributing object code is aproximately the same as distributing the binary, so no need to distribute source code if you don't like to do it.

Moreover, this only applies if you actually link against CPCtelera low-level library. You can use CPCtelera full building system and tools along with your own code and SDCC library code. Then you will not even have to distribute your object code, because you won't be linking against CPCtelera low-level library.

However, take into account that this is the default license for general use of CPCtelera. You can use CPCtelera in this way without asking for permission. But, at any time, any developer may ask authors for a particular license. If anyone wanted to do something that is out of the scope of the general license, we can give them a particular license or permission to do that.

In my university we tend to use GPL for almost everything. We discussed about LGPL for the case of CPCtelera to let games have their own source code closed. It was not an easy decision, but we finally thought it to be better. The spirit of CPCtelera is to be shared with everyone and maintain its free status forever (as long as Copyright lets it maintain that status). We don't want someone to create a new closed source version of CPCtelera in the future, and we want all add-ons, modifications, improvements, etc. to be equally available for everyone with the same freedom level. We want people to be able to use CPCtelera to create games and software, but also to learn from it as much as possible. We want people to be better developers and have the tools to develop and learn. That's the reason of the license.

Either the case, please, ask your doubts and tell me your objections or other ideas. We consider any exposed ideas, even if we finally discard them (not everything considered is implemented, of course). Also, take into account that we want to cover as many needs as possible, without contradicting our philosophy, but that won't probably ever include all possible needs. Sorry about that.

[reidrac]

@ronaldo: in my humble opinion, @Munchausen is probably right that GPL with a linking exception (like gcc or even SDCC do), could be what you're looking for.

If we look at the LGPL, I'm not sure if an object would link with an newer version of cpctelera anyway, so it might not be worth it. I could be wrong though.

With GPL + linking exception the library is free and will continue to be free (and changes to it would need to be released with any game binary), the project continues with the GPL philosophy, and anyone willing to go with a different licence for their game would be free to do that.

[ronaldo]

@reidrac : Essentially, LGPL is GPL with a linking exception. The reason not to create a new license is that, as FSF sais, it should be named differently and we will be responsible of the legal terms. So, at present, we prefer to stick to LGPL.

With respect to object code, this is what FSF sais in his FAQ about LGPL:

Does the LGPL have different requirements for statically vs dynamically linked modules with a covered work? (#LGPLStaticVsDynamic)
For the purpose of complying with the LGPL (any extant version: v2, v2.1 or v3):

(1) If you statically link against an LGPL'd library, you must also provide your application in an object (not necessarily source) format, so that a user has the opportunity to modify the library and relink the application.

(2) If you dynamically link (...)

For me it is clear that object code is the only requisite. Of course, a new version with a different API will prevent object code from linking, but I think that is not the spirit of the license. In that case, you will not only need source code, but also permission to adapt it, and may be you'll even have to refactor/recode it. So, I think the idea behind this is to be able to link against a personal modification that does not break API compatibility.

However, take into account that this is our intention as authors. We won't be pursuing people for not freeing source code if we are doing this change to let them do that. Everything is just a matter of respect: no need to get lost in details.

[Munchausen]

@reidrac : Essentially, LGPL is GPL with a linking exception. The reason not to create a new license is that, as FSF sais, it should be named differently and we will be responsible of the legal terms. So, at present, we prefer to stick to LGPL.

With respect to object code, this is what FSF sais in his FAQ about LGPL:For me it is clear that object code is the only requisite. Of course, a new version with a different API will prevent object code from linking, but I think that is not the spirit of the license. In that case, you will not only need source code, but also permission to adapt it, and may be you'll even have to refactor/recode it. So, I think the idea behind this is to be able to link against a personal modification that does not break API compatibility.

However, take into account that this is our intention as authors. We won't be pursuing people for not freeing source code if we are doing this change to let them do that. Everything is just a matter of respect: no need to get lost in details.

Yes the issue here is that people will have to distribute object files, if not source code (because you can't re-link a CPC executable easily). Still, this is an easier requirement than distributing source code, but more difficult than just distributing a linked executable. BTW, I don't mind what you do, and I think CPCtelera is a great piece of work. I also appreciate the spirit of the distribution terms, even if the license doesn't precisely match.

[ronaldo]

@Munchausen, thank you for your kind words and understanding, even not agreeing completely with our decision .

Just as quick remember, if someone wants to develop something special that falls out of the license, take 5 minutes to contact us by email and ask for permission. Surely, if you are going to invest 4 or 5 months of work, 5 to 10 minutes to ask for permission shouldn't break your schedule . We are open minded and can give special permisions depending on what the project is about.

Clearly, if someone is to make a million with an special license, we would like to take at least a part of it . Sadly, I don't think that will be the main case. For instance, an special permission for not having to distribute the object files when releasing a new demo might be perfectly okay .

[andycadley]

Having to ship object code has the same fundamental problems as shipping source code and will, ultimately, mean everyone is technically in violation of the license even though they probably don't mean to be. I tend to agree with those who say that applying any kind of licence at all to 8-bit source code is entirely pointless, but that's still up to authors to ultimately decide for themselves.

[ronaldo]

@andycadley well, that's technically unuseful. If you give no license to your code, that means all rights reserved. So, anyone would have to ask you permission even if the wanted to use your code without any kind of distribution. Licenses are the way to do a "default" transfer of some of your rights as authors to give others permission without going one-by-one. The only question is picking the right one at each time.

I personally don't think that distributing object code is difficult at all. CPCtelera generates a obj/ folder with all object code. You copy that folder along with your DSK/CDT file, erase those files you don't want, and distribute it. CPCtelera has taken thousands of hours to be developed, is given free and lets you create propietary software. I don't think asking for object code in return is much. Why is it so for you?

[andycadley]

@andycadley well, that's technically unuseful. If you give no license to your code, that means all rights reserved. So, anyone would have to ask you permission even if the wanted to use your code without any kind of distribution. Licenses are the way to do a "default" transfer of some of your rights as authors to give others permission without going one-by-one. The only question is picking the right one at each time.

"Code is given 'as is', do with it as you please" - literally all you need.

I personally don't think that distributing object code is difficult at all. CPCtelera generates a obj/ folder with all object code. You copy that folder along with your DSK/CDT file, erase those files you don't want, and distribute it. CPCtelera has taken thousands of hours to be developed, is given free and lets you create propietary software. I don't think asking for object code in return is much. Why is it so for you?

Because everyone has to do it everywhere, despite 99% of users not wanting it. Want to put a .DSK of the game on a website? You have to put it in a zip file with a bunch of other files that just confuse end users for the sake of it. Want to share a pre-release demo version with people to get feedback? You have to send them the object files too, with every version you send. Want to do a physical disk/tape release? You either have to put the object files on the tape/disk or provide a permanent link to the exact version of the source/object files for all time (and no, a GitHub/SourceForge etc link won't cut it - it has to be permanently available or you violate the license).

I'm all for sharing source code. Heck I think that people use CPCTelera should attribute your contribution to anything they build with it (a condition the GPL/LGPL forbids) because you've put an enormous amount of effort into it. However the GPL/LGPL as a license is literally the most unnecessarily burdensome license ever invented and the "protections" it provides are so entirely pointless in the world of 8-bit software, which has no commercial value whatsoever.

As I said though, it's up to authors what they choose to do.

[ronaldo]

@andycadley, man, I beg you please not to convert this into a flame war. Discussing different points of view is good for everyone if we are intelligent enough to maintain our discussion within respectful terms and, even more importantly, trying to be as objective as possible. If we let our tongues go out the respectful circle, we can create a perjudicial environment for all of us.

I understand your reasons against license restrictions, and they are mainly legitimate (some of them I think are missunderstandings). Its logical wanting to do whetever you want with code, and a valid point of view. However, I ask you to undestand that that's not valid for everyone, even if that is a personal view. For instance, I work for a public university in Spain as professor. Being that my personal profile, I must be finicky about legal issues of everything I make publicly available. For instance, an apparently innocent thing such as publishing an 8-bits software along with a "Code is given 'as is'" notice could potentially even destroy my life and my family's. This may sound exagerated, but it is an actual risk. As professor at a public institution, laws and public opinion would be much more severly applied to me on any problem that may arise related with any of my creations. Even if I do it perfect, there is still the risk if someone missunderstands something and publishes something about me that makes public opinion angry with me. So, excuse me, but i must be fully sure that what I do goes the correct way.

Out of that, I personally appreciate the values of guaranteed freedom in source code that GPL pursues. Without that, many things we use and know wouldn't probably exist the way they are today. I reckon that comes with the cost of some restrictions, but I personally think it is balanced.

With respect to distribution of object code again, some details I think it is important to clarify:

   
• You do not have to distribute object code along with your DSK/CDT if you don't want to. GPL states it clearly, and the FAQ explains it. You can do something as easy as putting a written offer committing you to send object code to anyone wanting it, and giving them a way to ask for it (say an email address).
• People using CPCtelera low-level library or any other GPL/LGPL program must always attribute CPCtelera authors their contribution. Natural author rights cannot be alienated, and recognizing you as author of your part is a natural author right included in copyright laws. Licenses cannot alienate that right, at least in Spain, and I assume that should be same in most countries.
• Techically, we are not using LGPL to protect commercial value. We are using GPL/LGPL licenses to protect intellectual value and, as you also have seen, to protect ourselves from potential legal issues. But, most importantly, what we want to protect, as a public institution, is the intelectual value of the code: we don't want it to be closed, acquired or legally claimed by anyone in the future that could prevent people from reading it, modifying it and learning from it. No one knows what the future will be, and it is important to try to preserve intellectually valuable productions accessible and free for everyone. That's the main reason for using GPL/LGPL licenses. Almost the same reason Linux and GNU have to GPL/LGPL everything.

However, man, we agree in that anyone of us have the right to pick up the license or the policy they want with their own productions. But please, take into account that our reasons, even not being your reasons, are for good. I think that we both agree in trying to beneficiate community and doing good with our productions.

[andycadley]

Certainly not looking for a flame war, just one of those areas where I've too often seen people dig themselves into a big hole by opting for the "default" option, particularly back in my days working for a university where it caused no end of headaches.

   

• You do not have to distribute object code along with your DSK/CDT if you don't want to. GPL states it clearly, and the FAQ explains it. You can do something as easy as putting a written offer committing you to send object code to anyone wanting it, and giving them a way to ask for it (say an email address).

Which has to remain a valid method of obtaining it. Forever. That's a hefty burden for someone to place on both themselves and their descendants and one of the many easily overlooked requirements of the GPL (and one of the reasons I always recommend people read and understand the full text of the GPL rather than the FSF's somewhat misleading FAQs). I know that most of the website URLs, email address, phone numbers etc I've had over the years have changed and disappeared. Not to mention having to retain every version of everything and be able to pluck out the correct version on request. The GPL burdens authors like this deliberately, because the aim is to always give the code in preference to any pre-built version. It's good for many circumstances but of questionable value for such niches as old 8-bit games.

It's your choice though. If I really felt the legal ramifications of releasing code required me to pick a license, I'd probably prefer BSD or Apache, they're much less of a minefield. YMMV.

[AMSDOS]

"Code is given 'as is', do with it as you please" - literally all you need.

I'd call that a waiver and that code will become Public Domain.


It's explained in Public-domain software on Wikipedia, that a waiver can be used to disclaim the copyright and other rights, otherwise it's subjected to Copyright.

[FloppySoftware]

I fully agree with Ronaldo. 

As I said in the thread mentioned here before, I had doubts about if the GPL suits my needs, but I don't like a "do what you like with this" license style for sure.

What I want for my projects is respect, that's all. If they are useful for someone, that's perfect.

And regarding money value of this kind of software projects, keep in mind that there are some new hardware projects sold with software compilations.

Normally, they have license agreements to distribute the software, but they may include also "public domain" or "do what you want with this" software.

In the last case, they earn some money with your program, and you are working for free.

If you don't care about that, it's ok, but if you do... well, just take a pill for the headache.

[andycadley]

Normally, they have license agreements to distribute the software, but they may include also "public domain" or "do what you want with this" software.

In the last case, they earn some money with your program, and you are working for free.

You do realise that the GPL not only allows them to do the same, it actually guarantees their right to charge for your work if they choose to do so(provided they share your source/object files)

[EgoTrip]

@ronaldo

This has left me confused. I need some clarifications.

Do I have to include everything in the /obj folder when I distribute it?  Or was that for the old license? Does "terms of my choice" mean I don't have to if I don't want to? (sorry I did not do that before but I was unaware, I admit I never read the license. I hate all that crap and it's legal language).

Also I am not comfortable opening my source code as it's pretty bad. When I get better at C then maybe I will consider it but for now its staying closed. But I would still be unlikely to open it to the public.

Where do I stand if I was to produce a hard copy of the game? If I did it I would sell at cost price, but in the extremely unlikely event if any profit were made would I legally be obliged to give you a cut (I would give you a cut of any profit regardless, just wanted to know).

I understand you own the rights to the libraries and the code included in cpctelera. But surely I own the rights to my own code? I guess this is why licensing is needed.

Does the "created using cpctelera" credit need to be in the actual program or is the documentation adequate? Or does it not matter where, as long as it is mentioned? I had no space for credits on Prelude so I put it on the manual. It will be in both on my current game.

Now don't misunderstand me here, this is not in any way understating the effort went into creating cpctelera. Without it many games would not exist for the CPC. But the creators of the game put as much effort into making their games, as you did putting into creating cpctelera. Which I guess is why you went for the fairer license and I'm glad you recognize that. Having more control over the finished product is only fair, but I do strongly feel credit should always be given and if any money is made then you should get a reasonable cut of the profits.

Which leads me on to the last point. I just distribute my games for free and have never bothered with any license. I guess I cannot use "all rights reserved" but I have always copyrighted myself in my games. What license are / can / should they be distributed under?

[seanb]

If only I knew how to programme. Would love to try this out.

[EgoTrip]

If only I knew how to programme. Would love to try this out.

I didn't know how either. I learned myself using examples and C tutorials online. Don't get C and C++ confused though. It's got a steep learning curve but once you get it, it makes a lot of sense. I'd never have thought I'd have been able to make the games I have done in C even a year ago.