This solves the problem that on iPad you would get 1024x768 instead
of 768x1024 when calling SDL_GetDesktopDisplayMode(0, &mode)
See Apple's doc for UIScreenMode where is says:
"Most developers should never need to use the information provided
by this class and should simply use the bounds provided by the
UIScreen object for their drawing space."
This is the rakefile from Andrey Nesterov, but slightly modified.
Use the following command:
$ rake -f Xcode-iPhoneOS/rakefile
The resulting framework is placed in the ./build directory.
Original email...
Date: Sat, 10 Sep 2011 13:01:20 -0500
From: Patrick Baggett
To: SDL Development List <sdl@lists.libsdl.org>
Subject: Re: [SDL] SDL_memcpyMMX uses SSE instructions
In SDL_blit_copy.c, the function SDL_memcpyMMX() actually use SSE
instructions.
It is called in this context:
#ifdef __MMX__
if (SDL_HasMMX() &&
!((uintptr_t) src & 7) && !(srcskip & 7) &&
!((uintptr_t) dst & 7) && !(dstskip & 7)) {
while (h--) {
SDL_memcpyMMX(dst, src, w);
src += srcskip;
dst += dstskip;
}
_mm_empty();
return;
}
#endif
This implies that the minimum CPU features are just MMX. There is a
separate SDL_memcpySSE() function.
The SDL_memcpyMMX() function does:
#ifdef __SSE__
_mm_prefetch(src, _MM_HINT_NTA);
#endif
...which tests at compile time if SSE intrinsics are available, not at run
time. It generates the PREFETCHNTA instruction. It also uses _mm_stream_pi()
intrinsic, which generates the MOVNTQ instruction.
If you replace the "MMX" code with:
__m64* d64 = (__m64*)dst;
__m64* s64 = (__m64*)src;
for(i= len / 64; i--;) {
d64[0] = s64[0];
d64[1] = s64[1];
d64[2] = s64[2];
d64[3] = s64[3];
d64[4] = s64[4];
d64[5] = s64[5];
d64[6] = s64[6];
d64[7] = s64[7];
d64 += 8;
s64 += 8;
}
Then MSVC generates the correct movq instructions. GCC (4.5.0) seems to
think that using 2x movl is still better, but then again, GCC isn't actually
that good at optimizing intrinsics as I've found. At least the code won't
crash on my P2 though. :)
Also, there is no requirement for MMX to be aligned to the 8th byte. I
think the author assumed that SSE's 16 byte alignment requirement must
retroactively mean that MMX requires 8 byte alignment. Attached is the full
patch.
Patrick
