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/**********************************************************************
Copyright (C) Antoine Mine' 2006
Motorola 6854 emulation (network interface).
**********************************************************************/
#ifndef MC6854_H
#define MC6854_H
class mc6854_device : public device_t
{
public:
mc6854_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock);
~mc6854_device() { global_free(m_token); }
// access to legacy token
void *token() const { assert(m_token != NULL); return m_token; }
protected:
// device-level overrides
virtual void device_config_complete();
virtual void device_start();
virtual void device_reset();
private:
// internal state
void *m_token;
};
extern const device_type MC6854;
/* we provide two interfaces:
- a bit-based interface: out_tx, set_rx
- a frame-based interface: out_frame, send_frame
The bit-based interface is low-level and slow.
Use it to simulate the actual bits sent into the wires, e.g., to connect
the emulator to another bit-based emulated network device, or an actual
device.
The frame-based interface is higher-level and faster.
It passes bytes directly from one end to the other without bothering with
the actual bit-encoding, synchronization, and CRC.
Once completed, a frame is sent through out_frame. Aborted frames are not
transmitted at all. No start flag, stop flag, or crc bits are trasmitted.
send_frame makes a frame available to the CPU through the 6854 (it may
fail and return -1 if the 6854 is not ready to accept the frame; even
if the frame is accepted and 0 is returned, the CPU may abort it). Ony
full frames are accepted.
*/
/* ---------- configuration ------------ */
typedef struct _mc6854_interface mc6854_interface;
struct _mc6854_interface
{
devcb_write_line out_irq_func; /* interrupt request */
/* low-level, bit-based interface */
devcb_read_line in_rxd_func; /* receive bit */
devcb_write_line out_txd_func; /* transmit bit */
/* high-level, frame-based interface */
void ( * out_frame ) ( device_t *device, UINT8* data, int length );
/* control lines */
devcb_write_line out_rts_func; /* 1 = transmitting, 0 = idle */
devcb_write_line out_dtr_func; /* 1 = data transmit ready, 0 = busy */
};
#define MCFG_MC6854_ADD(_tag, _intrf) \
MCFG_DEVICE_ADD(_tag, MC6854, 0) \
MCFG_DEVICE_CONFIG(_intrf)
#define MCFG_MC6854_REMOVE(_tag) \
MCFG_DEVICE_REMOVE(_tag)
/* ---------- functions ------------ */
/* interface to CPU via address/data bus*/
extern READ8_DEVICE_HANDLER ( mc6854_r );
extern WRITE8_DEVICE_HANDLER ( mc6854_w );
/* low-level, bit-based interface */
WRITE_LINE_DEVICE_HANDLER( mc6854_set_rx );
/* high-level, frame-based interface */
extern int mc6854_send_frame( device_t *device, UINT8* data, int length ); /* ret -1 if busy */
/* control lines */
WRITE_LINE_DEVICE_HANDLER( mc6854_set_cts ); /* 1 = clear-to-send, 0 = busy */
WRITE_LINE_DEVICE_HANDLER( mc6854_set_dcd ); /* 1 = carrier, 0 = no carrier */
/* clock */
WRITE_LINE_DEVICE_HANDLER( mc6854_rxc_w );
WRITE_LINE_DEVICE_HANDLER( mc6854_txc_w );
#endif
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