diff options
author | Vas Crabb <vas@vastheman.com> | 2018-07-07 02:40:29 +1000 |
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committer | Vas Crabb <vas@vastheman.com> | 2018-07-07 02:40:29 +1000 |
commit | c3fb11c2c98a5c28ece6a27093a0f9def350ac64 (patch) | |
tree | c68b38f05ed1d32358add721fda7f45e8803479f /src/devices/bus/ss50/mpc.cpp | |
parent | 5d9e33b786d7ef452317439359f3cbd8cc920513 (diff) |
devcb3
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.
Diffstat (limited to 'src/devices/bus/ss50/mpc.cpp')
-rw-r--r-- | src/devices/bus/ss50/mpc.cpp | 32 |
1 files changed, 16 insertions, 16 deletions
diff --git a/src/devices/bus/ss50/mpc.cpp b/src/devices/bus/ss50/mpc.cpp index 8489e23e29b..25a6ed43951 100644 --- a/src/devices/bus/ss50/mpc.cpp +++ b/src/devices/bus/ss50/mpc.cpp @@ -25,13 +25,13 @@ class ss50_mpc_device : public device_t, public ss50_card_interface public: // construction/destruction ss50_mpc_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock) - : device_t(mconfig, SS50_MPC, tag, owner, clock), - ss50_card_interface(mconfig, *this), - m_pia(*this, "pia"), - m_loopback(*this, "loopback"), - m_counter(*this, "counter"), - m_baud_jumper(*this, "BAUD"), - m_count_select(false) + : device_t(mconfig, SS50_MPC, tag, owner, clock) + , ss50_card_interface(mconfig, *this) + , m_pia(*this, "pia") + , m_loopback(*this, "loopback") + , m_counter(*this, "counter") + , m_baud_jumper(*this, "BAUD") + , m_count_select(false) { } @@ -101,15 +101,15 @@ DEVICE_INPUT_DEFAULTS_END //------------------------------------------------- MACHINE_CONFIG_START(ss50_mpc_device::device_add_mconfig) - MCFG_DEVICE_ADD("pia", PIA6821, 0) // actually MC6820 - MCFG_PIA_WRITEPA_HANDLER(WRITELINE("outgate", input_merger_device, in_w<0>)) MCFG_DEVCB_BIT(0) - MCFG_PIA_CB2_HANDLER(WRITELINE(*this, ss50_mpc_device, reader_control_w)) - MCFG_PIA_READPB_HANDLER(IOPORT("STOP")) MCFG_DEVCB_BIT(6) - MCFG_DEVCB_CHAIN_INPUT(READLINE(*this, ss50_mpc_device, count_r)) MCFG_DEVCB_BIT(7) - MCFG_PIA_WRITEPB_HANDLER(WRITELINE(*this, ss50_mpc_device, count_select_w)) MCFG_DEVCB_BIT(2) - MCFG_DEVCB_CHAIN_OUTPUT(WRITELINE("counter", ripple_counter_device, reset_w)) MCFG_DEVCB_BIT(0) - //MCFG_PIA_IRQA_HANDLER(WRITELINE(*this, ss50_mpc_device, pia_irq_w)) - //MCFG_PIA_IRQB_HANDLER(WRITELINE(*this, ss50_mpc_device, pia_irq_w)) + PIA6821(config, m_pia, 0); // actually MC6820 + m_pia->writepa_handler().set("outgate", FUNC(input_merger_device::in_w<0>)).bit(0); + m_pia->cb2_handler().set(FUNC(ss50_mpc_device::reader_control_w)); + m_pia->readpb_handler().set_ioport("STOP").mask(0x01).lshift(6); + m_pia->readpb_handler().append(FUNC(ss50_mpc_device::count_r)).lshift(7); + m_pia->writepb_handler().set(FUNC(ss50_mpc_device::count_select_w)).bit(2); + m_pia->writepb_handler().append(m_counter, FUNC(ripple_counter_device::reset_w)).bit(0); + //m_pia->irqa_handler().set(FUNC(ss50_mpc_device::pia_irq_w)); + //m_pia->irqb_handler().set(FUNC(ss50_mpc_device::pia_irq_w)); MCFG_DEVICE_ADD("rs232", RS232_PORT, default_rs232_devices, "terminal") MCFG_RS232_RXD_HANDLER(WRITELINE(*this, ss50_mpc_device, serial_input_w)) |