This commit introduces a large architectural change. Unlike previous
models of the fx-9860G series, the G-III models have a new user RAM
address different from 8801c000. The purpose of this change is to
dynamically load GMAPPED functions to this address by querying the TLB,
and call them through a function pointer whose address is determined
when loading.
Because of the overhead of using a function pointer in both assembly and
C code, changes have been made to avoid GMAPPED functions altogether.
Current, only cpu_setVBR() and gint_inth_callback() are left, the second
being used specifically to enable TLB misses when needed.
* Add a .gint.mappedrel section for the function pointers holding
addresses to GMAPPED functions; add function pointers for
cpu_setVBR() and gint_inth_callback()
* Move rram to address 0 instead of the hardcoded 0x8801c000
* Load GMAPPED functions at their linked address + the physical address
user RAM is mapped, to and compute their function pointers
* Remove the GMAPPED macro since no user function needs it anymore
* Add section flags "ax" (code) or "aw" (data) to every custom .section
in assembler code, as they default to unpredictable values that can
cause the section to be marked NOLOAD by the linker
* Update the main kernel, TMU, ETMU and RTC interrupt handlers to use
the new indirect calling method
This is made possible by new MMU functions giving direct access to the
physical area behind any virtualized page.
* Add an mmu_translate() function to query the TLB
* Add an mmu_uram() function to access user RAM from P1
The exception catching mechanism has been modified to avoid the use of
GMAPPED functions altogether.
* Set SR.BL=0 and SR.IMASK=15 before calling exception catchers
* Move gint_exc_skip() to normal text ROM
* Also fix registers not being popped off the stack before a panic
The timer drivers have also been modified to avoid GMAPPED functions.
* Invoke timer_stop() through gint_inth_callback() and move it to ROM
* Move and expand the ETMU driver to span 3 blocks at 0xd00 (ETMU4)
* Remove the timer_clear() function by inlining it into the ETMU handler
(TCR is provided within the storage block of each timer)
* Also split src/timer/inth.s into src/timer/inth-{tmu,etmu}.s
Additionally, VBR addresses are now determined at runtime to further
reduce hardcoded memory layout addresses in the linker script.
* Determine fx-9860G VBR addresses dynamically from mmu_uram()
* Determine fx-CG 50 VBR addresses dynamically from mmu_uram()
* Remove linker symbols for VBR addresses
Comments and documentation have been updated throughout the code to
reflect the changes.
This change ports the TLB management system to fx9860g through %003.
This raises the size limit for add-ins to about 500k.
Because SH3 fx9860g does not have ILRAM, the GMAPPED attribute has been
made to generate content to a .gint.mapped section which is sent to the
P1 RAM section historically dubbed "real ram" in which gint's data and
VBR are installed. (Now that I think about it, gint's data should try to
go to normal RAM instead to reduce pressure on this invasion.)
Return-to-menu was also fixed on both platforms by narrowing down the
need for code to remain mapped to the chance of running it with
interrupts disabled. The natural distribution of GMAPPED under this
criterion showed that _gint_setvbr had been left under TLB control;
moving it to the proper RAM area fixed gint switches.
Finally, an omission in the bound checks for mappable TEA addresses (TEA
>= 0x00300000) prevented the appearance of a non-interactible System
ERROR popup when some unmapped addresses are accessed.
This version still does not enable interrupts in timer callbacks,
exposing any application to a crash if a timer underflows while its
callback is not mapped. It is not suitable for any stable application!
t6k11: use the gint array for variant detection
r61524: use true triple buffering by default
display: define DWIDTH and DHEIGHT
display: add C_RGB(r,g,b) (0 ≤ r,g,b ≤ 31) [fxcg50]
This change introduces two new mechanismes for executing user code when
an exception occurs.
* This first is the custom panic message, which usually displays "System
ERROR". The function that performs this task can now be user-defined.
It is also run in user mode because the exception handler rte's into
it, allowing it to execute any kind of interrupt-inducing task. The
behavior is undefined if this function raises an exception.
* The second is an exception-catching function, which (when set) is
called every time an exception occurs, and is granted the chance of
handling the exception to continue execution normally. It can be used
in various ways, the most primitive of which is recording the
exception and going back. It runs in interrupt mode and must not raise
any kind of exception.
This change introduces exception handlers that default to a fatal error
with an on-screen description of the exception and some debugging
information.
It also adds the dprint() function as a definitely-needed helper and
removes bootlog_unmapped() by using the exception handler for the fatal
error display. (Also printf() is now required in all gint add-ins; this
is sad, but space is not as much of a constraint as debugging.)
Finally, the exception handler is used to handle an interrupt which is
an exception in practice, the DMA address error. On fx-CG 50, additional
DMA-related information is displayed on the screen. This is left out on
fx-9860G as there is not enough space.
Lephe
lephe