// Copyright (c) 2012 - 2026 kio@little-bat.de
// BSD-2-Clause license
// https://opensource.org/licenses/BSD-2-Clause

#pragma once
#include "Fdc.h"
#include "FloppyDiskDrive.h"


//	Emulation of a NEC µPD765 (with some errors…)
//	which is connected like this:
//
//	no DMA			send_byte_to_dma() and read_byte_from_dma() do nothing but may be reimplemented
//	no interrupts	raise_interrupt() and clear_interrupt() just set this.interrupt but may be reimplemented
//	no FM			MFM is always assumed.


namespace zxsp
{

class Fdc765 : public Fdc
{
	uint sm_state; // for coroutine macros
	uint sm_stack[8];
	uint sm_sp; // SM stack pointer

	// FDC command and arguments:
	uint32 CMD; // stored as mask: CMD = 1<<CMD !!
	uint8  head_unit, track_id, head_id, sector_id, log2sectorsize, gap3len;
	uint8  last_sector_id, num_sectors, fillbyte, sectorsize, step;
	uint8  requested_track[4]; // target track in step command

	// extracted data:
	bool multitrack, mfm, skip_bit; // bits 5…7 from CMD
	uint unit;						// selected drive: from HU (HeadUnit)
	uint head;						// selected head:  from HU (HeadUnit)

	// FDC status registers:
	uint8 MSR, SR0, SR1, SR2; // main SR, result phase SR0 … 2

	// Drive settings from command SPECIFY:
	Time headloadtime;
	Time headunloadtime;
	Time steprate;
	bool dma_disabled;

	// current track: (FDC internal counters)
	uint track[4]; // current tracks (as believed by internal counters)

	// internal timers:
	Time when_head_unloaded; // internal timer: head unload time
	Time timeout;			 // step, head load, or i/o timeout

	// FDC state
	bool terminal_count;
	bool ready; // last seen drive state (for interrupt)

	// misc. state machine variables:
	uint   idams, bytepos, n, z, size, ssize, indexpulses;
	uint16 crc;
	uint8  byte, actual_log2ssize; // byte_for_cpuxxxxx, byte_from_cpuxxxxx;
	bool   f, eq, le, ge, crc_on, skip;

	// up to which time the state machine ran:
	Time time;

public:
	Fdc765(Machine*, isa_id, Internal internal, cstr o_addr, cstr i_addr);

	uint8 readMainStatusRegister(Time);
	uint8 readDataRegister(Time);
	void  writeDataRegister(Time, uint8);

	void initForSnapshot(int32 cc) override;

protected:
	~Fdc765() override = default;

	// Item interface:
	void powerOn(/*t=0*/ int32 cc) override;
	void reset(Time, int32 cc) override;
	void input(Time, int32 cc, uint16 addr, uint8& byte, uint8& mask) override = 0;
	void output(Time, int32 cc, uint16 addr, uint8 byte) override			   = 0;
	void audioBufferEnd(Time) override;
	// void	videoFrameEnd	(int32 cc) override;

private:
	// DOIT:
	void run_statemachine(Time);
	void start_crc()
	{
		crc_on = yes;
		crc	   = 0xffff;
	}
	void  update_crc();
	void  cancel_crc() { crc_on = no; }
	bool  scan_satisfied();
	uint8 SR3();

	virtual bool is_fault() { return drive->is_error; }
	virtual bool is_2sided() { return drive->is_2sided; }
	bool		 is_wprot() { return drive->is_wprot; }
	bool		 is_track0() { return drive->is_track0; }
	bool		 is_ready() { return drive->is_ready; }
	bool		 is_atIndex() { return drive->is_atindex; }
	void		 _init();
};

} // namespace zxsp