adespoton wrote:
Programmingkid wrote:
Could IBM have made hidden registers in their PowerPC product that Apple was only told about? This could be the assumption about hardware Apple is making.
Apple was a co-designer with IBM and Motorola; original chips were manufactured by Motorola, with only the later ones being IBM. Since this didn't happen on the IBM chips (I had a G5), it seems that whatever they were doing was at least consistent across the implementations.
HOWEVER, the Quicktime engine for Intel/Windows was itself running inside a WINE-like layer; Quicktime for Windows (6 and earlier) was actually a cross-compiled Quicktime for Mac inside a virtual environment that presented the Mac toolbox calls.
And anyone who ever used Quicktime for Windows knows how horrible that experience was. There was the delay while the virtual environment booted up, and then the CPU was pegged while doing the audio processing. So it was doing something that didn't cross compile to x86 all that well. It's possible that we're running up against the same issue here; that Quicktime (and the audio toolbox calls) are making use of PPC functions/relationships that just don't translate well into a pipelined x86 architecture.
Your knowledge of Quicktime is impressive.
A while ago there was a lot of work being done to make OpenBIOS boot Mac OS 9. Someone on this forum referred to Apple's interesting forth code as "anti-emulation". I'm beginning to wonder if they do have code in their programs that prevent or discourage its use in an emulator. The code could be as simple as checking to see if the CPU is made by Motorola or IBM. If it isn't, make the user's life difficult.
I did another test were I ran this tiny MP3 decoder (
http://keyj.emphy.de/files/projects/minimp3.tar.gz) in Windows 2000 in qemu-system-i386. The MP3 playback was excellent. Its source code shows it using many floating point instructions. Here is a little sample:
static INLINE double __declspec(naked) libc_pow(double b, double e) { __asm {
fld qword ptr [esp+12]
fld qword ptr [esp+4]
fyl2x
// following is a copy of libc_exp:
fst st(1)
frndint
fxch
fsub st(0), st(1)
f2xm1
fld1
fadd
fscale
ret
} }
We still don't fully know what Quicktime is doing or why it is failing during MP3 playback. The only way we could is by reverse engineering it.
