* direct_read_data is now a template which takes the address bus shift
as a parameter.
* address_space::direct<shift>() is now a template method that takes
the shift as a parameter and returns a pointer instead of a
reference
* the address to give to {read|write}_* on address_space or
direct_read_data is now the address one wants to access
Longer explanation:
Up until now, the {read|write}_* methods required the caller to give
the byte offset instead of the actual address. That's the same on
byte-addressing CPUs, e.g. the ones everyone knows, but it's different
on the word/long/quad addressing ones (tms, sharc, etc...) or the
bit-addressing one (tms340x0). Changing that required templatizing
the direct access interface on the bus addressing granularity,
historically called address bus shift. Also, since everybody was
taking the address of the reference returned by direct(), and
structurally didn't have much choice in the matter, it got changed to
return a pointer directly.
Longest historical explanation:
In a cpu core, the hottest memory access, by far, is the opcode
fetching. It's also an access with very good locality (doesn't move
much, tends to stay in the same rom/ram zone even when jumping around,
tends not to hit handlers), which makes efficient caching worthwhile
(as in, 30-50% faster core iirc on something like the 6502, but that
was 20 years ago and a number of things changed since then). In fact,
opcode fetching was, in the distant past, just an array lookup indexed
by pc on an offset pointer, which was updated on branches. It didn't
stay that way because more elaborate access is often needed (handlers,
banking with instructions crossing a bank...) but it still ends up with
a frontend of "if the address is still in the current range read from
pointer+address otherwise do the slowpath", e.g. two usually correctly
predicted branches plus the read most of the time.
Then the >8 bits cpus arrived. That was ok, it just required to do
the add to a u8 *, then convert to a u16/u32 * and do the read. At
the asm level, it was all identical except for the final read, and
read_byte/word/long being separate there was no test (and associated
overhead) added in the path.
Then the word-addressing CPUs arrived with, iirc, the tms cpus used in
atari games. They require, to read from the pointer, to shift the
address, either explicitely, or implicitely through indexing a u16 *.
There were three possibilities:
1- create a new read_* method for each size and granularity. That
amounts to a lot of copy/paste in the end, and functions with
identical prototypes so the compiler can't detect you're using the
wrong one.
2- put a variable shift in the read path. That was too expensive
especially since the most critical cpus are byte-addressing (68000 at
the time was the key). Having bit-adressing cpus which means the
shift can either be right or left depending on the variable makes
things even worse.
3- require the caller to do the shift himself when needed.
The last solution was chosen, and starting that day the address was a
byte offset and not the real address. Which is, actually, quite
surprising when writing a new cpu core or, worse, when using the
read/write methods from the driver code.
But since then, C++ happened. And, in particular, templates with
non-type parameters. Suddendly, solution 1 can be done without the
copy/paste and with different types allowing to detect (at runtime,
but systematically and at startup) if you got it wrong, while still
generating optimal code. So it was time to switch to that solution
and makes the address parameter sane again. Especially since it makes
mucking in the rest of the memory subsystem code a lot more
understandable.
Disassemblers are now independant classes. Not only the code is
cleaner, but unidasm has access to all the cpu cores again. The
interface to the disassembly method has changed from byte buffers to
objects that give a result to read methods. This also adds support
for lfsr and/or paged PCs.
The core changes are:
* Short name, full name and source file are no longer members of device_t, they are part of the device type
* MACHINE_COFIG_START no longer needs a driver class
* MACHINE_CONFIG_DERIVED_CLASS is no longer necessary
* Specify the state class you want in the GAME/COMP/CONS line
* The compiler will work out the base class where the driver init member is declared
* There is one static device type object per driver rather than one per machine configuration
Use DECLARE_DEVICE_TYPE or DECLARE_DEVICE_TYPE_NS to declare device type.
* DECLARE_DEVICE_TYPE forward-declares teh device type and class, and declares extern object finders.
* DECLARE_DEVICE_TYPE_NS is for devices classes in namespaces - it doesn't forward-declare the device type.
Use DEFINE_DEVICE_TYPE or DEFINE_DEVICE_TYPE_NS to define device types.
* These macros declare storage for the static data, and instantiate the device type and device finder templates.
The rest of the changes are mostly just moving stuff out of headers that shouldn't be there, renaming stuff for consistency, and scoping stuff down where appropriate.
Things I've actually messed with substantially:
* More descriptive names for a lot of devices
* Untangled the fantasy sound from the driver state, which necessitates breaking up sound/flip writes
* Changed DECO BSMT2000 ready callback into a device delegate
* Untangled Microprose 3D noise from driver state
* Used object finders for CoCo multipak, KC85 D002, and Irem sound subdevices
* Started to get TI-99 stuff out of the TI-990 directory and arrange bus devices properly
* Started to break out common parts of Samsung ARM SoC devices
* Turned some of FM, SID, SCSP DSP, EPIC12 and Voodoo cores into something resmbling C++
* Tried to make Z180 table allocation/setup a bit safer
* Converted generic keyboard/terminal to not use WRITE8 - space/offset aren't relevant
* Dynamically allocate generic terminal buffer so derived devices (e.g. teleprinter) can specify size
* Imporved encapsulation of Z80DART channels
* Refactored the SPC7110 bit table generator loop to make it more readable
* Added wrappers for SNES PPU operations so members can be made protected
* Factored out some boilerplate for YM chips with PSG
* toaplan2 gfx
* stic/intv resolution
* Video System video
* Out Run/Y-board sprite alignment
* GIC video hookup
* Amstrad CPC ROM box members
* IQ151 ROM cart region
* MSX cart IRQ callback resolution time
* SMS passthrough control devices starting subslots
I've smoke-tested several drivers, but I've probably missed something. Things I've missed will likely blow up spectacularly with failure to bind errors and the like. Let me know if there's more subtle breakage (could have happened in FM or Voodoo).
And can everyone please, please try to keep stuff clean. In particular, please stop polluting the global namespace. Keep things out of headers that don't need to be there, and use things that can be scoped down rather than macros.
It feels like an uphill battle trying to get this stuff under control while more of it's added.
* Make device_creator a variable template and get rid of the ampersands
* Remove screen.h and speaker.h from emu.h and add where necessary
* Centralise instantiations of screen and speaker finder templates
* Add/standardise #include guards in many hearers
* Remove many redundant #includes
* Order #includesr to help catch headers that can't be #included alone
(nw) This changes #include order to be prefix, unit header if applicable
then other stuff roughly in order from most dependent to least dependent
library. This helps catch headers that don't #include things that they
use.
Use standard uint64_t, uint32_t, uint16_t or uint8_t instead of UINT64, UINT32, UINT16 or UINT8
also use standard int64_t, int32_t, int16_t or int8_t instead of INT64, INT32, INT16 or INT8
- Remove irq_line methods from M6502, M6800, M6809, S2600 and replace uses with DEVCB_INPUTLINE
- Remove a few IRQ passthroughs from spiders.cpp
- Add several aliases for M6800_IRQ_LINE
- Eliminate the cached device_t::m_region pointer and its region() getter method. Devices that need to bind to a region with the same tag should use optional/required_memory_region or optional/required_region_ptr with DEVICE_SELF as the subtag; this improves error checking. (DEVICE_SELF has been moved to device.h for greater visibility in the source.)
- Allow required/optional_region_ptr to specify a specific length which must match that of the region found.
- Implement finder_base::finder_tag() getter for diagnostic purposes.
- Perform some (not very efficient) validity checks on memory region finders instead of allowing them to automatically pass.
- Privatize device_memory_interface::m_addrspace.
Update MAME to use new function
Instantiate ODR-used static constant members
Make some of the UI code more localisable
Remove use of retired functions in tools
- strprintf is unaltered, but strformat now takes one fewer argument
- state_string_export still fills a buffer, but has been made const
- get_default_card_software now takes no arguments but returns a string
