There are multiple issues with the current device callbacks:
* They always dispatch through a pointer-to-member
* Chained callbacks are a linked list so the branch unit can't predict the early
* There's a runtime decision made on the left/right shift direction
* There are runtime NULL checks on various objects
* Binding a lambda isn't practical
* Arbitrary transformations are not supported
* When chaining callbacks it isn't clear what the MCFG_DEVCB_ modifiers apply to
* It isn't possible to just append to a callback in derived configuration
* The macros need a magic, hidden local called devcb
* Moving code that uses the magic locals around is error-prone
* Writing the MCFG_ macros to make a device usable is a pain
* You can't discover applicable MCFG_ macros with intellisense
* Macros are not scoped
* Using an inappropriate macro isn't detected at compile time
* Lots of other things
This changeset overcomes the biggest obstacle to remving MCFG_ macros
altogether. Essentially, to allow a devcb to be configured, call
.bind() and expose the result (a bind target for the callback). Bind
target methods starting with "set" repace the current callbacks; methods
starting with "append" append to them. You can't reconfigure a callback
after resolving it. There's no need to use a macro matching the
handler signatures - use FUNC for everything. Current device is implied
if no tag/finder is supplied (no need for explicit this).
Lambdas are supported, and the memory space and offset are optional.
These kinds of things work:
* .read_cb().set([this] () { return something; });
* .read_cb().set([this] (offs_t offset) { return ~offset; });
* .write_cb().set([this] (offs_t offset, u8 data) { m_array[offset] = data; });
* .write_cb().set([this] (int state) { some_var = state; });
Arbitrary transforms are allowed, and they can modify offset/mask for example:
* .read_cb().set(FUNC(my_state::handler)).transform([] (u8 data) { return bitswap<4>(data, 1, 3, 0, 2); });
* .read_cb().set(m_dev, FUNC(some_device::member)).transform([] (offs_t &offset, u8 data) { offset ^= 3; return data; });
It's possible to stack arbitrary transforms, at the cost of compile
time (the whole transform stack gets inlined at compile time). Shifts
count as an arbitrary transform, but mask/exor does not.
Order of mask/shift/exor now matters. Modifications are applied in the
specified order. These are NOT EQUIVALENT:
* .read_cb().set(FUNC(my_state::handler)).mask(0x06).lshift(2);
* .read_cb().set(FUNC(my_state::handler)).lshift(2).mask(0x06);
The bit helper no longer reverses its behaviour for read callbacks, and
I/O ports are no longer aware of the field mask. Binding a read
callback to no-op is not supported - specify a constant. The GND and
VCC aliases have been removed intentionally - they're TTL-centric, and
were already being abused.
Other quirks have been preserved, including write logger only logging
when the data is non-zero (quite unhelpful in many of the cases where
it's used). Legacy syntax is still supported for simple cases, but will
be phased out. New devices should not have MCFG_ macros.
I don't think I've missed any fundamental issues, but if I've broken
something, let me know.
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.
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
- 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
