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139 lines
3.5 KiB
C++
139 lines
3.5 KiB
C++
//
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// AY-3-8910.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 14/10/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#ifndef AY_3_8910_hpp
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#define AY_3_8910_hpp
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#include "../../Outputs/Speaker.hpp"
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namespace GI {
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namespace AY38910 {
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/*!
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A port handler provides all input for an AY's two 8-bit ports, and may optionally receive
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active notification of changes in output.
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Machines with an AY without ports or with nothing wired to them need not supply a port handler.
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Machines that use the AY ports as output but for which polling for changes is acceptable can
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instead use AY38910.get_port_output.
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*/
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class PortHandler {
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public:
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/*!
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Requests the current input on an AY port.
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@param port_b @c true if the input being queried is Port B. @c false if it is Port A.
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*/
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virtual uint8_t get_port_input(bool port_b) {
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return 0xff;
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}
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/*!
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Requests the current input on an AY port.
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@param port_b @c true if the input being queried is Port B. @c false if it is Port A.
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*/
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virtual void set_port_output(bool port_b, uint8_t value) {}
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};
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/*!
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Names the control lines used as input to the AY, which uses CP1600 bus semantics.
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*/
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enum ControlLines {
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BC1 = (1 << 0),
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BC2 = (1 << 1),
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BDIR = (1 << 2)
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};
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/*!
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Provides emulation of an AY-3-8910 / YM2149, which is a three-channel sound chip with a
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noise generator and a volume envelope generator, which also provides two bidirectional
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interface ports.
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*/
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class AY38910: public ::Outputs::Filter<AY38910> {
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public:
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/// Creates a new AY38910.
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AY38910();
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/// Sets the clock rate at which this AY38910 will be run.
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void set_clock_rate(double clock_rate);
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/// Sets the value the AY would read from its data lines if it were not outputting.
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void set_data_input(uint8_t r);
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/// Gets the value that would appear on the data lines if only the AY is outputting.
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uint8_t get_data_output();
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/// Sets the current control line state, as a bit field.
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void set_control_lines(ControlLines control_lines);
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/*!
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Gets the value that would appear on the requested interface port if it were in output mode.
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@parameter port_b @c true to get the value for Port B, @c false to get the value for Port A.
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*/
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uint8_t get_port_output(bool port_b);
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/*!
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Sets the port handler, which will receive a call every time the AY either wants to sample
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input or else declare new output. As a convenience, current port output can be obtained
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without installing a port handler via get_port_output.
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*/
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void set_port_handler(PortHandler *);
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// to satisfy ::Outputs::Speaker (included via ::Outputs::Filter; not for public consumption
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void get_samples(unsigned int number_of_samples, int16_t *target);
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private:
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int selected_register_;
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uint8_t registers_[16], output_registers_[16];
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uint8_t port_inputs_[2];
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int master_divider_;
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int tone_periods_[3];
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int tone_counters_[3];
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int tone_outputs_[3];
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int noise_period_;
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int noise_counter_;
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int noise_shift_register_;
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int noise_output_;
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int envelope_period_;
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int envelope_divider_;
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int envelope_position_;
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int envelope_shapes_[16][32];
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int envelope_overflow_masks_[16];
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int volumes_[16];
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enum ControlState {
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Inactive,
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LatchAddress,
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Read,
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Write
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} control_state_;
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void select_register(uint8_t r);
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void set_register_value(uint8_t value);
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uint8_t get_register_value();
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uint8_t data_input_, data_output_;
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int16_t output_volume_;
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inline void evaluate_output_volume();
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inline void update_bus();
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PortHandler *port_handler_;
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};
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}
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}
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#endif /* AY_3_8910_hpp */
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