The 16-bit DPCM decompressors in SSCI and Urban Runner use a 16-bit
register to store sample data, without any special handling of
overflow. As such, out-of-range samples simply wrap around, rather
than getting clipped.
It is not totally clear if the wrapping behaviour was intentionally
exploited to handle extreme transients, but in any case, videos
like GK2 5280.VMD that generate samples outside the signed 16-bit
range cause a loud pop when using clipping, but play back correctly
when wrapping.
DPCM decompression algorithms in SSCI operate directly on 8- and
16-bit registers, so any sample that ends up being out-of-range
during decompression gets wrapped by the CPU, not clipped.
This does not fix any known problem with AUD files, but there are
some VMDs (e.g. GK2 5280.VMD) which are known to contain OOR
samples. Making this code more accurate should prevent trouble
with any other similar files.
See matchKernelBreakpointPattern() for samples. The main envisioned use is
DoSound*,!DoSoundUpdateCues
to match all DoSound sub-functions except DoSoundUpdateCues.
This changes the syntax for bpk and logkernel:
Enable breakpoint on kernel call:
bpk FrameOut
Enable logging for kernel call:
bpk FrameOut log
For backward compatibility this has an alias: logkernel FrameOut
Removing a kernel call breakpoint is done with bp_del/bc now.
0f9c33e02f1cb2c740c1eb0dcaad96dd22ec29e7 in 2011 broke selector
breakpoints of the type "ObjName::", which previously caught all
selector sends of the named object.
Thanks to TMM and snover for noticing.
In SSCI, games could never start at tick 0 because the video
benchmarking code on game startup would take several ticks to
run. In ScummVM, where the benchmarking code is disabled, it
becomes possible for games to start at tick 0. This can break a
lot of kernel code, which uses tick 0 as a special value
indicating that a feature is not active. For example, in GK2,
the music at the start of the game will not fade in on systems
that are fast enough to start audio playback at tick 0, since
a fade start tick of 0 is used to indicate audio fade is disabled.
Fixes Trac#9830.
