6551.h

/*
**  Oricutron
**  Copyright (C) 2009-2014 Peter Gordon
**
**  This program is free software; you can redistribute it and/or
**  modify it under the terms of the GNU General Public License
**  as published by the Free Software Foundation, version 2
**  of the License.
**
**  This program is distributed in the hope that it will be useful,
**  but WITHOUT ANY WARRANTY; without even the implied warranty of
**  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
**  GNU General Public License for more details.
**
**  You should have received a copy of the GNU General Public License
**  along with this program; if not, write to the Free Software
**  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
**
**  6551 ACIA emulation
*/

// Registers
enum
{
  ACIA_RXDATA=0,
  ACIA_STATUS,
  ACIA_COMMAND,
  ACIA_CONTROL,
  ACIA_TXDATA,
  ACIA_LAST
};

// Command register bits
#define ACOMB_DTR    0
#define ACOMF_DTR    (1<<ACOMB_DTR)
#define ACOMB_IRQDIS 1
#define ACOMF_IRQDIS (1<<ACOMB_IRQDIS)
#define ACOMF_TXCON  0x0c
#define ACOMB_ECHO   2
#define ACOMF_ECHO   (1<<ACOMB_ECHO)
#define ACOMF_PARITY 0xe0

// Control register bits
#define ACONF_BAUD   0x0f
#define ACONB_SRC    4
#define ACONF_SRC    (1<<ACONB_SRC)
#define ACONF_WLEN   0x60
#define ACONB_STOPB  7
#define ACONF_STOPB  (1<<ACONB_STOPB)

// Status register bits
#define ASTB_PARITYERR 0
#define ASTF_PARITYERR (1<<ASTB_PARITYERR)
#define ASTB_FRAMEERR  1
#define ASTF_FRAMEERR  (1<<ASTB_FRAMEERR)
#define ASTB_OVRUNERR  2
#define ASTF_OVRUNERR  (1<<ASTB_OVRUNERR)
#define ASTB_RXDATA    3
#define ASTF_RXDATA    (1<<ASTB_RXDATA)
#define ASTB_TXEMPTY   4
#define ASTF_TXEMPTY   (1<<ASTB_TXEMPTY)
#define ASTB_CARRIER   5
#define ASTF_CARRIER   (1<<ASTB_CARRIER)
#define ASTB_DSR       6
#define ASTF_DSR       (1<<ASTB_DSR)
#define ASTB_IRQ       7
#define ASTF_IRQ       (1<<ASTB_IRQ)


// Back-ends
#ifdef __LINUX__
#define BACKEND_MODEM
#endif
#ifdef WIN32
#define BACKEND_MODEM
#endif
#ifdef __amigaos4__
#define BACKEND_MODEM
#endif
#ifdef __MORPHOS__
#define BACKEND_MODEM
#endif

#ifdef __LINUX__
#ifndef __ANDROID__
#define BACKEND_COM
#endif
#endif
#ifdef WIN32
#define BACKEND_COM
#endif

enum
{
  ACIA_TYPE_NONE = 0,
  ACIA_TYPE_LOOPBACK,
  ACIA_TYPE_MODEM,
  ACIA_TYPE_COM,

  ACIA_TYPE_LAST
};

// max length of back-end name
#define ACIA_BACKEND_NAME_LEN         128

/* Default port is telnet :23 */
#define ACIA_TYPE_MODEM_DEFAULT_PORT  23

struct acia
{
  struct machine *oric;
  Uint8 regs[ACIA_LAST];

  Uint32 cycles;
  Uint32 boudrate;
  Uint32 framebits;
  Uint32 framecycle;

  Uint8 bitmask;
  // RX/TX RXIRQ/TXIRQ flags
  SDL_bool rx;
  SDL_bool irqrx;
  SDL_bool tx;
  SDL_bool irqtx;
  // local loopback flag
  SDL_bool echo;

  // back-end api functions
  Uint8 (*stat)(Uint8 stat);
  SDL_bool (*has_byte)(Uint8* data);
  SDL_bool (*get_byte)(Uint8* data);
  SDL_bool (*put_byte)(Uint8 data);
  void (*done)(struct acia* acia);
};

void acia_init( struct acia *acia, struct machine *oric );
void acia_clock( struct acia *acia, unsigned int cycles );
void acia_write( struct acia *acia, Uint16 addr, Uint8 data );
Uint8 acia_read( struct acia *acia, Uint16 addr );

// Back-end init functions
SDL_bool acia_init_none( struct acia* acia );
SDL_bool acia_init_loopback( struct acia* acia );
#ifdef BACKEND_MODEM
SDL_bool acia_init_modem( struct acia* acia );
#endif
#ifdef BACKEND_COM
SDL_bool acia_init_com( struct acia* acia );
#endif