SDL/build-scripts
Anders Jenbo a8ecd677ed
Add DOS platform support (DJGPP) (#15377)
* dos: Some initial work.

* dos: Turn off buffer on stdio SDL_IOStreams.

Seeking breaks otherwise. We might be able to just fflush() before or seeking
instead?

* dos: Audio implementation using the Sound Blaster 16.

* dos: remove audio Pump interface.

Turns out DosBox-X was having trouble with the Sound Blaster or something;
standard DosBox works correctly directly from the interrupt handler, and
without doubling the buffer size.

* dos: just dump and restore the stdio buffer when seeking.

This is MUCH faster than just leaving buffering disabled, and also works
around getting bogus reads after an fseek. SDL_LoadWAV on test/sample.wav
no longer takes several seconds to finish, and comes up with the correct
data.

I wonder if we're triggering this in LoadWAV because we're malloc'ing data
between seeks/reads, and it's causing the djgpp transfer buffer to change. Or
maybe the Fat DS trick is confusing it? I don't know, I haven't had time to
debug it, it might just be a legit libc bug in djgpp too, for all I know.

* dos: Protect audio device "thread" iterations when streams are locked.

This uses an old trick we used in SDL 1.2 for MacOS Classic, which did its
audio callback in a hardware interrupt. If the audio is locked when the
interrupt fires, make a note of it and return immediately. When the lock is
released, if the interrupt has been fired, run the audio device iteration
right then.

Since there isn't a big device lock in SDL3 (available to the app, at least),
this keeps a counter of when any SDL_AudioStream is locked, which is probably
good enough.

* dos: Implemented initial video subsystem.

This uses VESA interfaces to manage the display and works with the software
renderer.

Events aren't hooked up yet, so prepare to close DosBox on each run.  :)

* dos: Whoops, forgot to add these to revision control. Core and Main support.

* dos: Wired up basic filesystem support.

This gets most of the rendering examples, which use SDL_GetBasePath() to
find textures to load, working.

* dos: Fixed compiler warning.

* dos: Initial mouse support!

* dos: Move interrupt hooking code into core/dos.

* dos: Initial keyboard support!

* dos: Use a simple ring buffer for keyboard events.

Of course Quake 1 solved this better, haha. It's smart: less memory, dirt
simple, and you don't even have to worry about synchronizing with the
interrupt handler, because it's safe for both sides no matter when an
interrupt fires.

* ci: add djgpp job

[sdl-ci-filter djgpp]
[sdl-ci-artifacts]

* dos: Fix build issues after rebase onto current main

- SDL_runapp.c: Add SDL_PLATFORM_DOS to the exclusion list so the
  generic
  SDL_RunApp() is disabled when the DOS-specific one is compiled.
- SDL.c: Exclude SDL_Gtk_Quit() on DOS. DJGPP defines __unix__ which
  sets
  SDL_PLATFORM_UNIX, but DOS has no GTK/display server. The GTK source
  is not compiled (CMake UNIX is false for DOS) so this was a link
  error.
- sdlplatform.cmake: Add DOS case to SDL_DetectCMakePlatform so the
  platform is properly detected from CMAKE_SYSTEM_NAME=DOS.
- i586-pc-msdosdjgpp.cmake: Add i386-pc-msdosdjgpp-gcc as a fallback
  compiler name, since some DJGPP toolchain builds use the i386 prefix.

* Add 8-bit palette support to DOS VESA driver

* Add VBE page-flipping, state restore, and robust keyboard handling

- Implement double-buffered page-flipping for VBE modes with >1 image
  page
- Save and restore full VBE state on video init/quit for clean mode
  switching
- Improve DOS keyboard handling: support extended scancodes and Pause
  key
- Lock ISR code/data to prevent page faults during interrupts
- Always vsync when blitting in single-buffered modes to reduce tearing

* Refactor Sound Blaster audio mixing to main loop

Move audio mixing out of IRQ handler to main loop for improved
stability and to avoid reentrancy issues. Add SDL_DOS_PumpAudio
function, update DMA buffer handling, and adjust sample rate to 22050
Hz.
Silence stale DMA buffer halves to prevent stutter during load.

* Add DOS timer support and update build config

* Add support for pre-SB16 8-bit mono Sound Blaster audio

Detect SB version and select 8-bit mono or 16-bit stereo mode.
Handle DMA and DSP setup for both SB16 and pre-SB16 hardware.
Add FORCE_SB_8BIT option for testing in DOSBox.

* Add SB Pro stereo support and simplify IRQ handler

* Add DOS joystick driver support

* Improve DOS hardware handling and clarify memory allocation

- Poll Sound Blaster DSP status instead of fixed delay after speaker-on
- Clarify DPMI conventional memory is always locked; update comments
- Document and justify DMA memory allocation strategy
- Free IRET wrapper after restoring interrupt vector to avoid leaks
- Throttle joystick axis polling to ~60 Hz to reduce BIOS timing loop
  cost
- Always poll joystick buttons directly for responsiveness

* Query and use mouse sensitivity from INT 33h function 0x1B

* Add support for VESA banked framebuffer modes

Implement banked framebuffer access for VBE 1.2+ modes without LFB.
Detect and initialize banked modes, copy framebuffer data using bank
switching, and blank the framebuffer on mode set. Page-flipping is
disabled in banked mode.

* Add optional vsync to page flipping in DOS VESA driver

* Add cooperative threading support for DOS platform

* Move SoundBlaster audio mixing to SDL audio thread

* Fix DOS platform comments and workarounds for DJGPP support

* Fix SoundBlaster IRQ handling and DMA setup for DOS

- Pass IRQ number to DOS_EndOfInterrupt and handle slave PIC EOI
- Validate DMA channel from BLASTER variable
- Correct DMA page register selection for SB16
- Improve BLASTER variable parsing and error messages
- Unmask/mask IRQs on correct PIC in DOS_HookInterrupt
- Rename SDL_dosjoystick.c to SDL_sysjoystick.c
- Include SDL_main_callbacks.h in SDL_sysmain_runapp.c
- Add include guard to SDL_systhread_c.h

* Add DOS platform options and preseed cache for DJGPP

Disable unsupported SDL features when building for DOS. Add
PreseedDOSCache.cmake to pre-populate CMake cache variables for DJGPP.

* cmake: use a 8.3 naming scheme for tests on DOS

* Apply code style

* Update include/SDL3/SDL_platform_defines.h

Co-authored-by: Anonymous Maarten <madebr@users.noreply.github.com>

* Code review clean up

- Split DOS VESA mode-setting into its own file
- Replace magic numbers with named constants
- Update copyright dates to 2026
- Substract time taken by other threads form delays

* Fix DOS bugs and improve compatibility

- Disable fseeko64 for DJGPP due to broken implementation
- Refactor DOS timer delay to always yield and avoid busy-waiting
- Fix animated cursor rendering in DOS VESA backend
- Always set display mode when creating DOS VESA window
- Work around DJGPP allowing invalid file access in testfile.c
- Bump max threads to 16
- Apply workarounds for threading tests

* Add DOS platform documentation and fix a few issues

- Fix fullscreen default resolution
- Improve best mode matching
- Fix builds on GCC older than 7.0
- Fix text input events

* Fix keyboard mapping of "*"

* Fix running, and existing, under PCem

* Apply suggestions from code review

Co-authored-by: Cameron Cawley <ccawley2011@gmail.com>

* Pre-mix audio in ring buffer and copy to DMA via IRQ thread

* Video fixes and optimizations

* DOS: Fix Intel 740 and VGA compatability

* DOS: Update readme

* DOS: Fix thread ID, get GPU name

* DOS: Cap mouse range

* DOS: Map test resources to 8.3 names

* DOS: Skip unsupported WM color modes

* Fix "windowed" resolution selection

* DOS: Hide INDEX8 modes behind SDL_DOS_ALLOW_INDEX8_MODES

* Remove SDL_HINT_DOS_ALLOW_INDEX8_MODES and order modes logically

* Don't convert cursor if dest is not INDEX8

---------

Co-authored-by: Ryan C. Gordon <icculus@icculus.org>
Co-authored-by: Anonymous Maarten <anonymous.maarten@gmail.com>
Co-authored-by: Cameron Cawley <ccawley2011@gmail.com>
Co-authored-by: Gleb Mazovetskiy <glex.spb@gmail.com>
Co-authored-by: Jay Petacat <jay@jayschwa.net>
Tested-by: Cameron Cawley <ccawley2011@gmail.com>
2026-04-23 19:54:49 -04:00
..
pkg-support CodeSpell 2026-02-07 18:14:00 +03:00
add-source-to-projects.pl winrt: Removed WinRT/Windows Phone/UWP support. 2024-09-06 13:28:39 -04:00
androidbuildlibs.sh Revert "Support Google Play 16 KB Page Size Requirement (#13470)" 2025-08-07 11:44:45 -07:00
build-release.py release: synchronize build-scripts/build-release.py 2026-01-21 21:49:41 +01:00
build-web-examples.pl Updated copyright for 2026 2026-01-01 09:40:08 -08:00
casefolding.txt stdlib: Improve Unicode support and consistency in string comparison functions. 2024-03-29 15:01:40 -04:00
check_android_jni.py check_android_jni.py: make sure we're using python3 2025-10-08 21:32:30 -07:00
check_elf_alignment.sh Add elf alignment check for Android artifacts (#13818) 2025-08-28 16:31:03 -07:00
check_stdlib_usage.py Updated copyright for 2026 2026-01-01 09:40:08 -08:00
clang-format-src.sh Added video/x11/edid.h to third party code list 2024-09-18 08:18:26 -07:00
cmake-toolchain-mingw64-i686.cmake cmake: add winres to the list of potential name rc compilers 2024-03-05 20:38:00 +01:00
cmake-toolchain-mingw64-x86_64.cmake cmake: add winres to the list of potential name rc compilers 2024-03-05 20:38:00 +01:00
cmake-toolchain-qnx-aarch64le.cmake Do not look at local headers when determining features 2023-03-27 15:33:08 -07:00
cmake-toolchain-qnx-x86_64.cmake Do not look at local headers when determining features 2023-03-27 15:33:08 -07:00
codechecker-buildbot.sh cmake: Prefix all options with "SDL_" 2021-10-05 10:45:26 -04:00
create-android-project.py Add parametrized build script 2024-10-14 21:30:48 +02:00
create-release.py create-release.py: use head of git ref as default commit 2024-11-02 04:20:32 +01:00
create_tbds.py Add script to generate macOS and iOS tbds 2025-11-26 01:03:41 +01:00
djgpp-platform-overrides.cmake Add DOS platform support (DJGPP) (#15377) 2026-04-23 19:54:49 -04:00
fnsince.pl fnsince.pl: Remove prerelease version tapdancing. 2025-01-21 13:10:57 -05:00
gen_audio_channel_conversion.c Updated copyright for 2026 2026-01-01 09:40:08 -08:00
git-pre-push-hook.pl Remove some vim config lines 2023-02-10 11:00:48 +01:00
i586-pc-msdosdjgpp.cmake Add DOS platform support (DJGPP) (#15377) 2026-04-23 19:54:49 -04:00
makecasefoldhashtable.pl Updated copyright for 2026 2026-01-01 09:40:08 -08:00
release-info.json Update NDK version to 28 (#13729) 2025-08-12 07:45:57 -07:00
rename_api.py Added the examples directory to the API renaming tool 2024-09-18 08:32:30 -07:00
rename_headers.py Define SDL_PLATFORM_* macros instead of underscored ones (#8875) 2024-01-24 01:40:51 +00:00
rename_macros.py ngage: Remove Nokia N-Gage support. 2024-12-11 13:29:43 -05:00
rename_symbols.py Added "--substring" to the help for rename_symbols.py 2023-10-23 09:14:54 -07:00
rename_types.py Added a script to help with the bool rename 2024-09-18 10:48:11 -07:00
SDL_migration.cocci SDL_migration.cocci: Fixed a few incorrect function names. 2025-08-02 22:54:03 -04:00
setup-gdk-desktop.py Fixed crashes in Metal renderer due to ARC releasing references on random memory in newly allocated structs 2024-09-05 19:48:33 -07:00
showrev.sh Moved the SDL version back to SDL_version.h 2024-05-15 14:38:29 -07:00
test-versioning.sh Revert "Separate android initialization from Activity (#11891)" 2025-01-10 15:27:08 -08:00
update-copyright.sh Use GNU sed if available 2023-02-06 15:47:16 -08:00
update-version.sh Revert "Separate android initialization from Activity (#11891)" 2025-01-10 15:27:08 -08:00
updaterev.sh Add parametrized build script 2024-10-14 21:30:48 +02:00
wikiheaders.pl wikiheaders: Don't escape . chars in manpage's brief section. 2026-04-15 13:28:52 -04:00