mirror of
https://github.com/TomHarte/CLK.git
synced 2024-11-06 12:07:57 +00:00
82 lines
1.9 KiB
C++
82 lines
1.9 KiB
C++
//
|
|
// SCSI.hpp
|
|
// Clock Signal
|
|
//
|
|
// Created by Thomas Harte on 12/08/2019.
|
|
// Copyright © 2019 Thomas Harte. All rights reserved.
|
|
//
|
|
|
|
#ifndef SCSI_hpp
|
|
#define SCSI_hpp
|
|
|
|
#include <limits>
|
|
#include <vector>
|
|
|
|
namespace SCSI {
|
|
|
|
typedef int BusState;
|
|
|
|
static const BusState DefaultBusState = 0;
|
|
|
|
/*!
|
|
SCSI bus state is encoded entirely within an int.
|
|
Bits correlate mostly but not exactly to the real SCSI bus.
|
|
|
|
TODO: validate levels below. The bus uses open collector logic,
|
|
so active low needs to be respected.
|
|
*/
|
|
enum Line: BusState {
|
|
/// Provides the value currently on the data lines.
|
|
Data = 0xff,
|
|
/// Parity of the data lines.
|
|
Parity = 1 << 8,
|
|
/// Set if the SEL line is currently selecting a target.
|
|
/// Reset if it is selecting an initiator.
|
|
SelectTarget = 1 << 9,
|
|
/// Set to indicate an attention condition. Reset otherwise.
|
|
Attention = 1 << 10,
|
|
/// Set if control is on the bus. Reset if data is on the bus.
|
|
Control = 1 << 11,
|
|
/// Set if the bus is busy. Reset otherwise.
|
|
Busy = 1 << 12,
|
|
/// Set if acknowledging a data transfer request. Reset otherwise.
|
|
Acknowledge = 1 << 13,
|
|
/// Set if a bus reset is being requested. Reset otherwise.
|
|
Reset = 1 << 14,
|
|
/// Set if data is currently an input to the initiator. Reset if it is an output.
|
|
Input = 1 << 15,
|
|
/// Set during the message phase. Reset otherwise.
|
|
Message = 1 << 16,
|
|
/// Set if requesting a data transfer. Reset otherwise.
|
|
Request = 1 << 17,
|
|
};
|
|
|
|
|
|
class Bus {
|
|
public:
|
|
/*!
|
|
Adds a device to the bus, returning the index it should use
|
|
to refer to itself in subsequent calls to set_device_output.
|
|
*/
|
|
size_t add_device();
|
|
|
|
/*!
|
|
Sets the current output for @c device.
|
|
*/
|
|
void set_device_output(size_t device, BusState output);
|
|
|
|
/*!
|
|
@returns the current state of the bus.
|
|
*/
|
|
BusState get_state();
|
|
|
|
private:
|
|
std::vector<BusState> device_states_;
|
|
BusState state_ = DefaultBusState;
|
|
bool state_is_valid_ = false;
|
|
};
|
|
|
|
}
|
|
|
|
#endif /* SCSI_hpp */
|