José Fonseca
bb8f3090ba
gcc-4.2's optimizer has a strange bug where it looses code from inner
loops in certain situations. For example, if the appearently innocent
looking code below is compiled with gcc-4.2 -S -O1, the inner loop's
code is missing from the outputed assembly.
struct Size {
unsigned width;
};
struct Command {
unsigned length;
struct Size sizes[32];
};
extern void emit_command(void *command, unsigned length);
void
create_surface( struct Size size, unsigned faces, unsigned levels)
{
struct Command cmd;
unsigned face;
unsigned level;
cmd.length = faces*levels*sizeof(cmd.sizes[0]);
for(face = 0; face < faces; ++face) {
for(level = 0; level < levels; ++level) {
cmd.sizes[face*levels + level] = size;
// This should generate a shrl statement, but the whole for body
// disappears in gcc-4.2 -O1/-O2/-O3!
size.width >>= 1;
}
}
emit(&cmd, sizeof cmd.length + cmd.length);
}
Note that this is not specific to MinGW's gcc-4.2 crosscompiler (the
version typically found in debian/ubuntu's mingw32 packages). gcc-4.2 on
Linux also displays the same error. gcc-4.3 and above gets this
correctly though.
Updated MinGW debian packages with gcc-4.3 are available from
http://people.freedesktop.org/~jrfonseca/debian/pool/main/m/
WindML Driver for Mesa 4.0
Requirements
------------
Tornado 2 + WindML, Cumulative Patchs are recommended.
I suppose you have a valid WindML installation. Double buffer hardware
gives better performance than double buffer software so if you can
compile your WindML driver with this option, just do it. I/O
redirection is adviced in target server.
Tested on
---------
During the development, my main target was a CoolMonster:
- Video card: CT69000
- CPU: PENTIUM 266MHz
and my host a Windows NT + Tornado 2.
Installation
------------
1. Mesa sources must be in root directory (C:\)
2. Add the following line to your torVars.bat:
set MESA_BASE=C:\Mesa
OR copy the new torVars.bat in your bin path:
c:/Mesa/src/ugl/tornado/torVars.sample ->
/mnt/nt/Tornado/host/x86-win32/bin/torVars (for example)
3. In a command prompt:
$ torVars
$ cd c:\Mesa
$ make -f Makefile.ugl CPU=PENTIUM
Take a long while...
5. Include all the files from ugldemos folder to build some downloadable
application modules
4. Download UGL/Mesa object files on target
For example via the WindShell:
ld < c:\Tornado\target\lib\objMesaGL.o
ld < c:\Tornado\target\lib\objMesaUGL.o
ld < c:\Tornado\target\lib\objMesaGLU.o
ld < c:\Tornado\target\lib\objGLUTshapes.o
ld < c:\Tornado\target\lib\objMesaOS.o
You can put the previous lines in a file and use:
< filename
6. Download the application modules.
7. In WindShell, run:
-> uglalldemos
During the show some messages will appear, it provides some useful
information on key management.
Coding
------
Sample Usage:
In addition to the usual ugl calls to initialize UGL, (may be find an
input driver), you must do the following to use the UGL/Mesa interface:
1. Call uglMesaCreateContext() to create a UGL/Mesa rendering context,
given the display format.
2. Call uglMesaMakeCurrent() to bind the UGL/Mesa buffers to an
UGL/Mesa Context and to make the context the current one.
3. Make gl* calls to render your graphics.
4. Use uglMesaSwapBuffers() when double buffering to swap front/back buffers.
5. Before the UGL is destroyed, call MesaDestroyContext().
6. Before exiting, call if required uglEventQDestroy and then
uglDeinitialize();
Limitations
-----------
I found the following limitations in my driver :
- Color Indexed management is only in 8 bits
- It's possible to mix UGL/OpenGL application with a software
double buffer
Modifications
------------
New files in Mesa:
- Makefile.ugl
- rules.windmlmesa
- docs/README.UGL
- include/GL/uglmesa.h
- si-glu/Makefile.ugl
- src/Makefile.ugl
- src/ugl/torGLUTShapesInit.c
- src/ugl/torMesaUGLInit.c
- src/ugl/ugl_api.c
- src/ugl/ugl_dd.c
- src/ugl/ugl_glutshapes.c
- src/ugl/ugl_line.c
- src/ugl/ugl_span.c
- src/ugl/ugl_tri.c
- src/ugl/uglmesaP.h
- ugldemos/*
Modified files in Tornado 2.0:
- c:\Tornado\host\x86-win32\bin\torVars.bat
rem Command line build environments
set WIND_HOST_TYPE=x86-win32
set WIND_BASE=C:\Tornado
set MESA_BASE=C:\Mesa
set PATH=%WIND_BASE%\host\%WIND_HOST_TYPE%\bin;%PATH%
- c:\Tornado\target\config\comps\VxWorks\01uglmesa.cdf
- c:\Tornado\target\h\GL\*
Todo
----
- GCC 2.96, ASM compilation
Thanks to:
----------
Precision Insight team for their great job around Mesa, XFree, and DRI.
Wind River Systems to take me as an intern.
Stephane Raimbault
<stephane.raimbault@windriver.com>
<stephane.raimbault@deesse.univ-lemans.fr>
July 24, 2001