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Added documentation.

This commit is contained in:
Thomas Harte 2017-08-16 09:14:56 -04:00
parent f18206767f
commit 82367a2246

View File

@ -14,14 +14,36 @@
namespace GI {
namespace AY38910 {
/*!
A port handler provides all input for an AY's two 8-bit ports, and may optionally receive
active notification of changes in output.
Machines with an AY without ports or with nothing wired to them need not supply a port handler.
Machines that use the AY ports as output but for which polling for changes is acceptable can
instead use AY38910.get_port_output.
*/
class PortHandler {
public:
/*!
Requests the current input on an AY port.
@param port_b @c true if the input being queried is Port B. @c false if it is Port A.
*/
virtual uint8_t get_port_input(bool port_b) {
return 0xff;
}
/*!
Requests the current input on an AY port.
@param port_b @c true if the input being queried is Port B. @c false if it is Port A.
*/
virtual void set_port_output(bool port_b, uint8_t value) {}
};
/*!
Names the control lines used as input to the AY, which uses CP1600 bus semantics.
*/
enum ControlLines {
BC1 = (1 << 0),
BC2 = (1 << 1),