From c3fb11c2c98a5c28ece6a27093a0f9def350ac64 Mon Sep 17 00:00:00 2001 From: Vas Crabb Date: Sat, 7 Jul 2018 02:40:29 +1000 Subject: 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. --- src/devices/cpu/s2650/s2650.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'src/devices/cpu/s2650') diff --git a/src/devices/cpu/s2650/s2650.h b/src/devices/cpu/s2650/s2650.h index 666c79cad5b..9bf1f03cf2f 100644 --- a/src/devices/cpu/s2650/s2650.h +++ b/src/devices/cpu/s2650/s2650.h @@ -28,13 +28,13 @@ DECLARE_DEVICE_TYPE(S2650, s2650_device) #define MCFG_S2650_SENSE_INPUT(_devcb) \ - devcb = &downcast(*device).set_sense_handler(DEVCB_##_devcb); + downcast(*device).set_sense_handler(DEVCB_##_devcb); #define MCFG_S2650_FLAG_OUTPUT(_devcb) \ - devcb = &downcast(*device).set_flag_handler(DEVCB_##_devcb); + downcast(*device).set_flag_handler(DEVCB_##_devcb); #define MCFG_S2650_INTACK_HANDLER(_devcb) \ - devcb = &downcast(*device).set_intack_handler(DEVCB_##_devcb); + downcast(*device).set_intack_handler(DEVCB_##_devcb); class s2650_device : public cpu_device, public s2650_disassembler::config { @@ -46,6 +46,9 @@ public: template devcb_base &set_sense_handler(Object &&cb) { return m_sense_handler.set_callback(std::forward(cb)); } template devcb_base &set_flag_handler(Object &&cb) { return m_flag_handler.set_callback(std::forward(cb)); } template devcb_base &set_intack_handler(Object &&cb) { return m_intack_handler.set_callback(std::forward(cb)); } + auto sense_handler() { return m_sense_handler.bind(); } + auto flag_handler() { return m_flag_handler.bind(); } + auto intack_handler() { return m_intack_handler.bind(); } protected: // device-level overrides -- cgit v1.2.3-70-g09d2