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gint
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Alternative library and kernel for add-in development on fx-9860G and fx-CG50 under Linux.
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Lephe c9264a06d5
kernel: driver and world system overhaul 
Changes in the driver and world system:

* Rewrite driver logic to include more advanced concepts. The notion of
  binding a driver to a device is introduced to formalize wait(); power
  management is now built-in instead of being handled by the drivers
  (for instance DMA). The new driver model is described in great detail
  in <gint/drivers.h>

* Formalized the concept of "world switch" where the hardware state is
  saved and later restored. As a tool, the world switch turns out to be
  very stable, and allows a lot of hardware manipulation that would be
  edgy at best when running in the OS world.

* Added a GINT_DRV_SHARED flag for drivers to specify that their state
  is shared between worlds and not saved/restored. This has a couple of
  uses.

* Exposed a lot more of the internal driver/world system as their is no
  particular downside to it. This includes stuff in <gint/drivers.h>
  and the driver's state structures in <gint/drivers/states.h>. This is
  useful for debugging and for cracked concepts, but there is no
  API stability guarantee.

* Added a more flexible driver level system that allows any 2-digit
  level to be used.

Feature changes:

* Added a CPU driver that provides the VBR change as its state save.
  Because the whole context switch relied on interrupts being disabled
  anyway, there is no longer an inversion of control when setting the
  VBR; this is just part of the CPU driver's configuration. The CPU
  driver may also support other features such as XYRAM block transfer
  in the future.

* Moved gint_inthandler() to the INTC driver under the name
  intc_handler(), pairing up again with intc_priority().

* Added a reentrant atomic lock based on the test-and-set primitive.
  Interrupts are disabled with IMASK=15 for the duration of atomic
  operations.

* Enabled the DMA driver on SH7305-based fx-9860G. The DMA provides
  little benefit on this platform because the RAM is generally faster
  and buffers are ultimately small. The DMA is still not available on
  SH3-based fx-9860G models.

* Solved an extremely obnoxious bug in timer_spin_wait() where the
  timer is not freed, causing the callback to be called when interrupts
  are re-enabled. This increments a random value on the stack. As a
  consequence of the change, removed the long delays in the USB driver
  since they are not actually needed.

Minor changes:

* Deprecated some of the elements in <gint/hardware.h>. There really is
  no good way to "enumerate" devices yet.

* Deprecated gint_switch() in favor of a new function
  gint_world_switch() which uses the GINT_CALL abstraction.

* Made the fx-9860G VRAM 32-aligned so that it can be used for tests
  with the DMA.

Some features of the driver and world systems have not been implemented
yet, but may be in the future:

* Some driver flags should be per-world in order to create multiple
  gint worlds. This would be useful in Yatis' hypervisor.
* A GINT_DRV_LAZY flag would be useful for drivers that don't want to
  be started up automatically during a world switch. This is relevant
  for drivers that have a slow start/stop sequence. However, this is
  tricky to do correctly as it requires dynamic start/stop and also
  tracking which world the current hardware state belongs to.
 		2021-04-23 20:44:08 +02:00
cmake cmake: use POSIX sed only for BSD/Mac OS compatibility 2021-04-17 14:48:12 +02:00
include/gint kernel: driver and world system overhaul 2021-04-23 20:44:08 +02:00
src kernel: driver and world system overhaul 2021-04-23 20:44:08 +02:00
.gitignore add GiteaPC support 2021-01-16 18:29:32 +01:00
CMakeLists.txt kernel: driver and world system overhaul 2021-04-23 20:44:08 +02:00
README.md kernel: move VBR at the end of the user RAM area on fx-9860G 2021-02-15 09:46:59 +01:00
TODO kernel: driver and world system overhaul 2021-04-23 20:44:08 +02:00
fx9860g.ld kernel: driver and world system overhaul 2021-04-23 20:44:08 +02:00
fxcg50.ld kernel: driver and world system overhaul 2021-04-23 20:44:08 +02:00
giteapc.make kmalloc: implement a custom segregated list allocator 2021-03-15 15:04:24 +01:00

README.md

gint project

gint (pronounce “guin”) is an add-in unikernel for CASIO calculators of the fx-9860G II and fx-CG 50 families. It provides a mostly free-standing runtime and is used to develop add-ins under Linux, along with specialized GCC toolchains and the fxSDK.

When running in an add-in, gint takes control of the calculator's hardware from the operating system, and manages it with its own drivers. It exposes a new, richer API that takes advantage of the full capabilities of the machine.

This is free software: you may use it for any purpose, share it, modify it, and share your changes. Credit is not required, but please let me know!

gint also includes third-party code that is distributed under its own license. Currently, this includes:

Programming interface

Because of its free-standing design, gint's API provides direct and efficient access to low-level MPU features, which includes:

  • Multi-key management with event systems suitable for games
  • Hardware timers with sub-millisecond and sub-microsecond resolution
  • Fast screen drivers with DMAC on fx-CG 50
  • Efficient and user-extendable interrupt management
  • Safe access to on-chip and DSP memory areas
  • Hardware-driven memory primitives (DMA, DSP)

The library also offers powerful higher-level features:

  • An enhanced version of the system's GetKey() and GetKeyWait()
  • A gray engine that works by rapidly swapping monochrome images on fx-9860G II
  • Blazingly fast rendering functions (image rendering is 10 times faster tha MonochromeLib)
  • Integrated font management

A couple of libraries extend these features, including:

Installing with GiteaPC

gint can be installed automatically with GiteaPC.

% giteapc install Lephenixnoir/gint

Normally you don't use gint directly, instead the fxSDK provides project templates that are set up to use gint. Please see the fxSDK README file for details.

Building and installing manually

gint is built using the fxSDK, which provides a suitable CMake environment for the calculator. gint is always installed in the compiler's install path (as given by sh-elf-gcc --print-search-dirs) which is detected automatically, so normally you don't need to set the install prefix.

fx-CG 50 developers probably want a g3a wrapper as well; the reference implementation is Tari's mkg3a. This is needed at the very last compilation step to create the g3a file. On Arch Linux, you can use the AUR/mkg3a package maintained directly by Tari.

Building for fx-9860G II

fxsdk build-fx will invoke CMake and make. If you have specific configuration options, run once with -c to configure.

% fxsdk build-fx -c <OPTIONS...>

Run without -c to build. This configures automatically.

% fxsdk build-fx

The available options are:

  • -DGINT_STATIC_GRAY=1: Put the gray engine's VRAMs in static RAM instead of using malloc()

Building for fx-CG 50

Same as fx-9860G II, except the command is fxsdk build-cg instead of fxsdk build-fx.

The available options are:

  • -DGINT_USER_VRAM=1: Store all VRAMs in the user stack (takes up 350k/512k)

Using in CMake-based add-ins

Find the Gint module and link against Gint::Gint.

find_module(Gint 2.1 REQUIRED)
target_link_libraries(<target_name> Gint::Gint)

Using in Makefile-based add-ins

Projects created with the fxSDK link with gint out-of-the-box. If you're not using the fxSDK, you will need to:

  • Build with -ffreestanding -fstrict-volatile-bitfields;
  • Link with -T fx9860g.ld and -lgint-fx on fx-9860G;
  • Link with -T fxcg50.ld and -lgint-cg on fx-CG 50.

If you don't have a standard library such as Memallox's port of newlib, you also need -nostdlib. I typically use -m3 -mb or -m4-nofpu -mb to specify the platform, but that may not even be necessary.