text: // license:BSD-3-Clause
  // copyright-holders:Couriersud
  /**********************************************************************
  
      8 bit latch interface and emulation
  
      Generic emulation of 74LS174/175, 74LS259 and other latches.
      Apart from providing synched latch operation, these
      latches can be configured to read their input bitwise from other
      devices as well.
  
      Please see audio/dkong.c for examples.
  
  **********************************************************************/
  
  #ifndef MAME_MACHINE_LATCH8_H
  #define MAME_MACHINE_LATCH8_H
  
  #pragma once
  
  
  class latch8_device : public device_t
  {
  public:
  	latch8_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock = 0);
  
  	// Write bit to discrete node
  	template <unsigned N> auto write_cb() { return m_write_cb[N].bind(); }
  
  	// Upon read, replace bits by reading from another device handler
  	template <unsigned N> auto read_cb() { return m_read_cb[N].bind(); }
  
  	// Bit mask specifying bits to be masked *out*
  	void set_maskout(uint32_t maskout) { m_maskout = maskout; }
  
  	// Bit mask specifying bits to be inverted
  	void set_xorvalue(uint32_t xorvalue) { m_xorvalue = xorvalue; }
  
  	// Bit mask specifying bits not needing cpu synchronization.
  	void set_nosync(uint32_t nosync) { m_nosync = nosync; }
  
  	// write & read full byte
  	uint8_t read(offs_t offset);
  	void write(offs_t offset, uint8_t data);
  
  	// reset the latch
  	void reset_w(offs_t offset, uint8_t data);
  
  	// read bit x
  	// FIXME: does not honour read callbacks or XOR mask
  	DECLARE_READ_LINE_MEMBER( bit0_r ) { return BIT(m_value, 0); }
  	DECLARE_READ_LINE_MEMBER( bit1_r ) { return BIT(m_value, 1); }
  	DECLARE_READ_LINE_MEMBER( bit2_r ) { return BIT(m_value, 2); }
  	DECLARE_READ_LINE_MEMBER( bit3_r ) { return BIT(m_value, 3); }
  	DECLARE_READ_LINE_MEMBER( bit4_r ) { return BIT(m_value, 4); }
  	DECLARE_READ_LINE_MEMBER( bit5_r ) { return BIT(m_value, 5); }
  	DECLARE_READ_LINE_MEMBER( bit6_r ) { return BIT(m_value, 6); }
  	DECLARE_READ_LINE_MEMBER( bit7_r ) { return BIT(m_value, 7); }
  
  	// read inverted bit
  	// FIXME: does not honour read callbacks or XOR mask
  	DECLARE_READ_LINE_MEMBER( bit0_q_r ) { return BIT(~m_value, 0); }
  	DECLARE_READ_LINE_MEMBER( bit1_q_r ) { return BIT(~m_value, 1); }
  	DECLARE_READ_LINE_MEMBER( bit2_q_r ) { return BIT(~m_value, 2); }
  	DECLARE_READ_LINE_MEMBER( bit3_q_r ) { return BIT(~m_value, 3); }
  	DECLARE_READ_LINE_MEMBER( bit4_q_r ) { return BIT(~m_value, 4); }
  	DECLARE_READ_LINE_MEMBER( bit5_q_r ) { return BIT(~m_value, 5); }
  	DECLARE_READ_LINE_MEMBER( bit6_q_r ) { return BIT(~m_value, 6); }
  	DECLARE_READ_LINE_MEMBER( bit7_q_r ) { return BIT(~m_value, 7); }
  
  	// write bit x from data into bit determined by offset
  	// latch = (latch & ~(1<<offset)) | (((data >> x) & 0x01) << offset)
  	void bit0_w(offs_t offset, uint8_t data);
  	void bit1_w(offs_t offset, uint8_t data);
  	void bit2_w(offs_t offset, uint8_t data);
  	void bit3_w(offs_t offset, uint8_t data);
  	void bit4_w(offs_t offset, uint8_t data);
  	void bit5_w(offs_t offset, uint8_t data);
  	void bit6_w(offs_t offset, uint8_t data);
  	void bit7_w(offs_t offset, uint8_t data);
  
  protected:
  	// device-level overrides
  	virtual void device_start() override;
  	virtual void device_reset() override;
  	virtual void device_validity_check(validity_checker &valid) const override;
  
  	TIMER_CALLBACK_MEMBER( timerproc );
  	void update(uint8_t new_val, uint8_t mask);
  	template <int Bit> void bitx_w(offs_t offset, uint8_t data);
  
  private:
  	devcb_write_line::array<8> m_write_cb;
  	devcb_read_line::array<8> m_read_cb;
  
  	// internal state
  	uint8_t            m_value;
  	bool               m_has_write;
  	bool               m_has_read;
  
  	// only for byte reads, does not affect bit reads and node_map
  	uint32_t           m_maskout;
  	uint32_t           m_xorvalue;  // after mask
  	uint32_t           m_nosync;
  };
  
  DECLARE_DEVICE_TYPE(LATCH8, latch8_device)
  
  #endif // MAME_MACHINE_LATCH8_H
  