Chaos Engine » C++

Qt and GCC 4.7.0 -std=c++0x

akiko — Mon, 06 Feb 2012 16:08:36 +0000

Another bump. Switching to gcc 4.7.0 and trying to compile my qt code with -std=c++0x, fails legendary. The error message is intuitive like ever. It says something like:

error: inconsistent user-defined literal suffixes '_FILE_' and 'QTOSTRING' in string literal

According to this

https://bugreports.qt-project.org/browse/QTBUG-22847?focusedCommentId=168644&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel

According to this, here is the solution, at least until we get new qt, or recompile it ourselves, or I don’t know what:

Magick: override fix for qt and c++0x

#define QLOCATION “\0″ __FILE__ “:” QTOSTRING(__LINE__)

Add this before any Qt includes. It solved my problem.

GCC 4.7.0 on Ubuntu 10.10

akiko — Fri, 20 Jan 2012 13:57:28 +0000

I needed to have gcc 4.6+ on my laptop to compile some c++11 code, which my gcc 4.4.4 from synaptic wasn’t able to handle. Yes, yes ‘update your ubuntu’ is the default warcry in such situations, but I didn’t want that to happen, not yet. So I needed a second gcc in my system. This is a reminder post to myself, nothing spectacular, it’s a bit dirty as well, and it’s already thoroughly documented here http://gcc.gnu.org/faq.html#multiple

What I did was, checked out the latest gcc from svn. Configured it with ./configure –prefix=/usr/local/gcc-4.7.0 –program-suffix=-4.7.0 (btw that suffix is completely unnecessary because all files will anyway be dumped in a folder named gcc-4.7.0) and than called make -j10 (yes I went out, grabbed some food, a coffee, got back and it at that very second it was done). make install finally to install it into /usr/local/gcc-4.7.0/

Additionally I’ve overridden the existing symlinks to let me use the new gcc as default gcc:

ln -s /usr/local/gcc-4.7.0/bin/g++-4.7.0 /usr/bin/g++ -f

ln -s /usr/local/gcc-4.7.0/bin/gcc-4.7.0 /usr/bin/gcc -f

And one last thing, for programs compiled with 4.7.0 you need to tie in the new libstdc++ as well, otherwise you’ll get an expected error message when executing them. Each libstdc++ covers all previous versions, but cannot cover future versions. For example, with my gcc 4.4.4 from synaptic the libstdc++ version was: 6.0.7. The new gcc 4.7.0 comes with libstdc++ 6.0.14.

Just like the gcc and g++ a symlink for libstdc++ exists in /usr/lib. We need to override that one as well:

ln -s /usr/lib/libstdc++.so.6 libstdc++.so.6.0.14 -f

And that’s it. Of course, there are some other libs like the one for objective c etc. that need to be symlinked. OR you can make your own shell script that sets LD and exe paths accordingly, and while working in that context, you can use the selected gcc version. I will try this out, and add it to this post, one day .. soon?

Amiga C Book accompanying floppy – “Grafik in C”

akiko — Sun, 03 Jul 2011 07:59:35 +0000

What a wonderful, inspiring weekend, spent writing some C in Cygnus Editor. Few months ago a coder from my demo group from the nineties found his Amiga 1200 with a fully functional and kicking hard disk. In one of its deeply nested, completely deprived of any systematical approach, ‘drawers’ (that’s how folders were called on amiga), I’ve bumped into the contents of one of the rarest books for amiga, low profile, cheaply done, published only in Germany, never translated to english, called: Grafik In C. But it has tons of hints (quite valuable today) on how to do some advanced gfx coding in C (copper, blitter, viewports, pixel manipulation, basic 3d etc.).

SO, I decided to share it with anyone who might be in need of good tutorials:

http://almagest.modmancer.com/data/grafik_in_c.zip

Qmake and targets (pre-building dependencies)

akiko — Sun, 14 Nov 2010 20:07:22 +0000

When using qmake as your build system, if you have a project which depends on a, e.g. external_library.a, you will need to set it up so that it can rebuild the library automatically, whenever the external library changes. In Visual studio this is easily done via its GUI, project properties, dependencies section, but when it comes to qmake, it requires a bit of extra effort to set things properly up. But it’s easy, once you know how.

HEARD OF TARGETS?

Qmake uses ‘targets’, thet’re like modules which you define, and insert into the main build chain, telling the resulting Makefile when to build what. Targets can be auto-executed, or simply residing in your make file, so that you can build them on demand.

Here is a simple example, covering the external_library.a story above.
In your main .pro file, add these lines:

extralib.target = extra
extralib.commands =	echo "Building extralib.."; \
				make -w -C ../my_libraries/extralib; \
				echo "Done building extralib."; \
extralib.depends =
QMAKE_EXTRA_TARGETS += extralib
PRE_TARGETDEPS = extra

.. the rest of your .pro file comes here ..
}

From now on, when building your main project, it will automatically try to build the extralib project. This step will be executed before the linker requests the resulting extralib.a, that way you will always have a consistent build.

But you can do much more with targets, you can for example set up doxygen to automatically export new docs on rebuilds, or to copy files, add text to your files – svn revision number maybe, or else.

If you leave out the PRE_TARGETDEPS = extra, the extralib target you defined will not be automatically execute during builds. But you will be able to type in your shell:

$ make extra

.. which will execute this specific target.

Additionally, if one of your targets depends on other target(s), you just need to add them to the ‘extralib.depends =’ variable. Note that you can execute a shell script via targets, in case you need to do complex file operation, which would be too painful to write in the .pro file, or which depend on external shell scripts.

Dirty debug output in DeSmuMe

akiko — Sun, 10 Oct 2010 10:47:13 +0000

Looking for a printf replacement when coding NDS homebrew?

Okay, (i)printf is nice, most of the time, but sometimes (actually quite often) you just can’t use it, be it for reasons like you’ve exhausted all video memory locations, or you need both screens, if you are coding something more complex than a simple effect, or you just can’t fit the complete debug output onto 256×192 pixels. There are several solutions to this problem (log to file using fatlib, send debug via Wifi, setup complete DeSmuMe debugging environment with eclipse), but here I will add one more.

Warning – this one is dirty like hell, and there is absolutely no guarantee that it will work (unless you write your own absolute mem manager).

So, here is the plan – DeSmuMe comes as CLI, gtk and glade. We need the DeSmuMe-glade, you’ll automatically get it if you install DeSmuMe from synaptic. This glade verision features a very handy tool, namely the hex memory viewer. This means, your code can write something let say at location 0×00000000 – 0×00001000 and you will clearly see it in the hex dump. Here’s an example :

And here is a simple code:

#include #define BUFFER_SIZE 1024 char* mem_p = (char*)0x00000000; void mem_log(bool reset, const char *format, ...) { char in_buf[BUFFER_SIZE]; char out_buf[BUFFER_SIZE * 2]; va_list vargs; // Compile the string. va_start (vargs, format); vsnprintf(in_buf, BUFFER_SIZE, format, vargs); va_end(vargs); snprintf(out_buf, BUFFER_SIZE, "%s ## ", in_buf); if (reset) mem_p = (char*)0x00000000; char* p = out_buf; while (*p != '\0') *mem_p++ = *p++; }

To use this simply:

mem_log(true, "Hello world!"); for(int i=0; i

Again, if you are not controlling mallocs yourself, there is no guarantee that you will not cause some serious program flaws by overwriting some sensitive data around 0×00000000. This is just a quick debug solution, if you are tired of trying to get libfat to work on an emulator.

Crossplatform QueryPerformanceTimer

akiko — Sun, 26 Sep 2010 10:25:32 +0000

Here is a simple way to get high precision timer on both Linux and Windows (can’t remember where I saw parts of this code, but I hope wrapping it up and spreading it won’t make the author angry) :

cross_platform_timer.h
cross_platform_timer.cpp

I added few helper wrappers to make the life easier, you can get current time in microseconds or milliseconds by calling:

//! Returns current time in milisecs or microsecs. //! \param micro Returns micro seconds if set to true. double timer_get(bool micro = false);

Or you can get elapsed time by calling:

timer_start(); // Your code here.. // Get elapsed time in milliseconds. double dt = timer_stop();

error: ‘glActiveTextureARB’ was not declared in this scope

akiko — Thu, 23 Sep 2010 09:31:00 +0000

If this happens to you, you most likely have NVidia gfx card, and the set up has poked the gl.h. To remedy this without having to reinstall anything, just add this to your code, before calling #include :

#define GL_GLEXT_PROTOTYPES 1 #include

For some reason th glActiveTextureARB prototype is under #ifdef GL_GLEXT_PROTOTYPES section. Adding the define yourself should workaround the problem. Hope it works in your case too.

Wrap numbers around power of 2 borders

akiko — Fri, 03 Sep 2010 22:29:54 +0000

I was working yesterday on some texture sampler, and recalled a simple thingy that was a great help back in the 90′s, which I completely forgot in recent years. If you have a counter, sampler or whatever that has to get wrapped around e.g. 256, 512 or any other power of two, you can use the following ultra fast hack:

// Wrap around 2^10 int x = some_fn(x) & 1023;

This will wrap whatever x is, around 1024 limiter. For example if x is 1025, it will become 1. 1026 will turn over to 2 etc. Still better than:

x = some_fn(x); x = x > 1023 ? x - 1024 : x;

My darkish Komodo and QT Creator color schemes

akiko — Sat, 17 Jul 2010 16:43:58 +0000

You can download my Komodo and Qt Creator ‘dark’ themes from:

http://www.modmancer.com/downloads/dev_blog/dew_dark.ksf
http://www.modmancer.com/downloads/dev_blog/dew_dark.xml

For Komodo:
copy the Komodo theme to your ~/.komodoide/5.2/schemes folder.

For Qt Creator 2.0:
copy the Qt Creator theme to your ~/.config/Nokia/qtcreator/styles folder.