These files assume, that WIN32 is defined by compiler or MSVC project
file, when in MSYS2 and MinGW environments, it is defined in config.h
and appears after dosbox.h is included, which in turn is included by
associated header (cdrom.h in this case).
Fixes: #42
Thanks to @ripsaw8080 for insight into CD-DA channel mapping,
@hail-to-the-ryzen for testing and flagging a position-tracking bug,
and @dreamer_ for guidance and code review.
The CD-DA volume and channel mapping loops were moved to generic mixer
calls and no longer require a pre-processing loop:
- Application-controlled CD-DA volume adjustment is now applied using
an existing mixer volume scalar that was previously unused by the
CD-DA code.
- Mapping of CD-DA left and right channels is now applied at the tail
end of the mixer's sample ingest sequence.
The following have been removed:
- The CD-DA callback chunk-wise circular buffer
- The decode buffers in the Opus and MP3 decoders
- The decode buffer and conversion buffers in SDL_Sound
These removals and API changes allow the image player's buffer
to be passed-through ultimately to the audio codec, skipping multiple
intermediate buffers.
Runtime improvements:
- Replaces the existing audio callback routine with an efficient chunked
circular-buffer audio reader
- Replaces assumptions that all audio tracks are 44.1 kHz & stereo.
The mixer is now fed data at the actual compressed track's rate and
channel count
- Eliminates all SDL locks in the audio code in favour of mixer state
control
- Queries the codec for track-length instead of using hundreds of
iterative decimating seeks to determine track length (loading
a 99-track CUE now takes 0.1 user-seconds versus 3+ seconds
previously)
- Seeks are performed within the already-decoded buffer (for all
codecs) instead of discarding and re-running the decode sequence
- SDL_Sound's buffer-size is now set once and never resized, which
eliminates repeated re-malloc'ing in the library
- Only one seek is performed per-playback sequence followed by
sequential decodes, similar to a physical CDROM (The baseline dosbox
performs a seek for every 2352-bytes of uncompressed audio)
- The DOSBox mixer is now only active during playback sequences and
fully dormant otherwise (baseline dosbox instead performs hundreds of
calls/second with empty data)
- When using Opus audio tracks, and if your dosbox.conf [mixer]
rate=48000, then you will (very likely) achieve sample-exact
unadulterated pass-through along your entire audio chain from the
decoder, to DOSBox, to your operating system's software mixer,
to your sound card driver, to your sound card, to your speakers,
or to your digital receiver / USB speakers/headphones / or HDMI
TV/screen. This is because almost all modern hardware DACs use
a native sample rate of 48000
Source-level maintenance improvements:
- It strips all pre-processor #ifdef branching for SDL_Sound from
the code
- Fixes all codec compiler warnings (in the modified files); builds
have been tested with GCC 4 to 10, Clang 6 to 10, and MSVC 14
- Tested on Linux, macOS (Xcode), and Windows (MinGW MSYS 1.0)
operating systems
- Tested on i386, x86_64, ARM, and PowerPC (big-endian) architectures
Macros FRAMES_TO_MSF and MSF_TO_FRAMES come from SDL_cdrom library.
SDL_cdrom was removed from SDL2 and these macros are used also in code
not directly related to SDL_cdrom library, so a replacement is needed.
Turns out output pointer type is different on Windows (int*) than it is on
Linux (unsigned char*); given choice between using void* for parameters and
a template function, I prefer template.
Should fix that directories with the same length as a deleted directory had some small issues.
Also blocks the creation of files in directories marked as deleted.
Small speed up to MakeDir, so it doesn't rely on mkdir when a directory is created inside a deleted directory.
Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@4268
- Fix Bit8u instead of char weirdness for imageDisk (dreamer_)
- Give device_t a virtual empty destructor so some warning program
doesn't go crazy.
- Give the code that moves the Z drive its own function for readability.
- Give sizes arrays default values again for warning program.
- Rewrite IMGMOUNT in order to exit early for clarity and attempt
to group things together.
Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@4267
When active, this drive redirects new and changed files to a different location.
The files in the overlay and normal drive are merged on startup and kept up to date when the game changes something.
Files in the overlay are priotizedi, if they exists, above the normal files.
The drive will switch to an overlayed version of the file on the first write! (Not when opening the file in write-mode).
The overlay is capable of creating missing directories.
With the help of DBOVERLAY files, the drive keeps track of files that are present in the normal directory but deleted by the game.
All changes are preserved between sessions.
Current design principles/limitations/requirements:
1) All directories that can be used for saving, must exist already in the base before mounting. (they will be created by DOSBox if missing in the overlay)
2) All filenames inside the overlay directories are UPPERCASE and conform to the 8.3 standard except for the special DBOVERLAY files.
3) To keep point 1 valid at all times, support for creating/renaming/removing directories has been disabled.
Thanks for the help GOG.
Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@4196
