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Avoid unnecessary get_port_input calls.

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This commit is contained in:
Thomas Harte 2021-11-24 17:15:48 -05:00
parent 2a7a42ff8f
commit 55af6681af
1 changed files with 4 additions and 2 deletions
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6
Components/6526/Implementation/6526Implementation.hpp
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@ -31,8 +31,10 @@ template <int port> void MOS6526<BusHandlerT, personality>::set_port_output() {
template <typename BusHandlerT, Personality personality>
template <int port> uint8_t MOS6526<BusHandlerT, personality>::get_port_input() {
const uint8_t input = port_handler_.get_port_input(Port(port));
return (input & ~data_direction_[port]) | (output_[port] & data_direction_[port]);
// Avoid bothering the port handler if there's no input active.
const uint8_t input_mask = ~data_direction_[port];
const uint8_t input = input_mask ? port_handler_.get_port_input(Port(port)) : 0x00;
return (input & input_mask) | (output_[port] & data_direction_[port]);
}
template <typename BusHandlerT, Personality personality>