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Diffstat (limited to 'doc/dev notes.txt')
| -rw-r--r-- | doc/dev notes.txt | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/doc/dev notes.txt b/doc/dev notes.txt index 1bc9ccd..3aa2db5 100644 --- a/doc/dev notes.txt +++ b/doc/dev notes.txt @@ -53,6 +53,44 @@ IRQs are only triggered on transfer completion. Additional notes by spicyjpeg: +* The controller/memory card SPI interface is poorly implemented in most +emulators, making custom controller polling code insanely hard to write and +debug. The only emulator that comes close to real hardware is no$psx, which +seems to correctly implement all features of the SPI port (even those not used +by the BIOS pad driver, such as TX/RX interrupts). DuckStation only emulates +the bare minimum required by the BIOS and Sony libraries, and pcsx-redux has +major bugs that break most custom polling implementations. This pretty much +means TX/RX IRQs and many flags in the JOY_* registers should not be used +unless you are willing to break compatibility with emulators. + +* As if communicating with controllers wasn't difficult enough already, +DualShock pads also have a built-in watchdog timer that gets enabled when first +putting them in configuration mode (and is NOT disabled after exiting config +mode). If no polling commands are sent to the controller for about 1 second, +vibration motors are switched off and analog mode is disabled; the same happens +if the analog button is pressed while in analog mode. In order to always keep +the pad in analog mode you must: + + * Poll both controller ports at least once per frame by sending command 42h. + Polling at a higher rate might be desirable in some cases (such as rhythm + games) to increase timing accuracy. + * If a digital pad response (type = 4) is received from a port that hasn't + previously been flagged as digital-only, attempt to put the pad into config + mode using command 43h *twice* (as the proper response is delayed). + * If the pad doesn't recognize the config command, flag it as digital-only + and treat all further digital pad responses from it as valid. + * If the pad recognizes the command, it will reply by identifying as an + analog pad in config mode (type = 15). Send command 44h immediately + (without sending 42h first, otherwise the pad will exit config mode) to + enable analog mode and turn on the LED. + * Pressing the analog button will result in the controller identifying as + digital even though it is not flagged as such, thus re-triggering the + configuration process and putting it back into analog mode. + * All analog pad responses (type = 7) can be treated as valid, as they will + come from controllers that have already been configured. + * If no valid response is received, assume no controller is connected and + reset the port's digital-only flag. + * The SDK provides no support yet for replacing the BIOS exception handler with a custom one, however it can be done (if you are ok with losing all BIOS controller, memory card and file functionality). In order not to break anything @@ -128,6 +166,38 @@ cache or something like that (?). The only workaround I know of is to use CPACK_PRE_BUILD_SCRIPTS to trigger a custom script that deletes anything other than the actual files to be packaged (see cpack/fakeroot_fix.cmake). +* Project installation might fail on macOS (and possibly some Linux distros) if +CMake attempts to set permissions on system directories such as /usr/local. +This is usually caused by install() commands that copy files to the root +installation directory rather than to a subfolder, like this: + + install( + DIRECTORY install_tree/ + DESTINATION . + USE_SOURCE_PERMISSIONS + ) + +If the USE_SOURCE_PERMISSIONS flag is specified CMake will attempt to set +permissions on the DESTINATION folder, which in this case would be the root +prefix (/usr/local by default on macOS), to match the source directory. This +will however fail as macOS restricts top-level system directories from having +their permissions changed. The simplest workaround is to avoid using +"DESTINATION ." and install each subdirectory explicitly instead, like this: + + foreach( + _dir IN ITEMS + ${CMAKE_INSTALL_BINDIR} + ${CMAKE_INSTALL_LIBDIR} + ${CMAKE_INSTALL_INCLUDEDIR} + ${CMAKE_INSTALL_DATADIR} + ) + install( + DIRECTORY install_tree/${_dir}/ + DESTINATION ${_dir} + USE_SOURCE_PERMISSIONS + ) + endforeach() + * Depending on how you find external dependencies (find_package(), vcpkg, pkg-config...), CMake may end up outputting an executable that relies on a DLL installed system-wide. To correctly install the DLL alongside the executable |