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6821.cpp

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6821.cpp

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/*
* mc6821.c - MC6821 emulation for the 1571 disk drives with DD3.
*
* Written by
* Andreas Boose <viceteam@t-online.de>
*
* This file is part of VICE, the Versatile Commodore Emulator.
* See README for copyright notice.
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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., 59 Temple Place, Suite 330, Boston, MA
* 02111-1307 USA.
*
*/
/*#define MC_DEBUG*/
#include "StdAfx.h"
#include "6821.h"
#define PIA_W_CALLBACK(st, val) \
if ( st.func ) st.func( st.objTo, val )
/*-----------------------------------------------------------------------*/
/* MC6821 register functions. */
void C6821::mc6821_write_pra(BYTE byte, unsigned int dnr)
{
//if (mc6821[dnr].drive->parallel_cable == DRIVE_PC_DD3)
// parallel_cable_drive_write(byte, PARALLEL_WRITE, dnr);
mc6821[dnr].pra = byte;
if (mc6821[dnr].ddra) // AppleWin:TC
PIA_W_CALLBACK( m_stOutA, mc6821[dnr].pra & mc6821[dnr].ddra );
}
void C6821::mc6821_write_ddra(BYTE byte, unsigned int dnr)
{
//parallel_cable_drive_write((BYTE)((~byte) | mc6821[dnr].pra), PARALLEL_WRITE, dnr);
if (mc6821[dnr].ddra == byte) // AppleWin:TC
return;
mc6821[dnr].ddra = byte;
if (mc6821[dnr].ddra) // AppleWin:TC
PIA_W_CALLBACK( m_stOutA, mc6821[dnr].pra & mc6821[dnr].ddra );
}
BYTE C6821::mc6821_read_pra(unsigned int dnr)
{
BYTE byte = m_byIA; // AppleWin:TC
//BYTE byte = 0xff;
//int hs = 0;
//if ((mc6821[dnr].cra & 0x28) == 0x28)
// hs = 1;
//if (mc6821[dnr].drive->parallel_cable == DRIVE_PC_DD3)
// byte = parallel_cable_drive_read(hs);
mc6821[dnr].cra = (BYTE)(mc6821[dnr].cra & 0x7f);
mc6821[dnr].cra = (BYTE)(mc6821[dnr].cra & 0xbf); // AppleWin:TC (Clear IRQ2)
return (mc6821[dnr].pra & mc6821[dnr].ddra)
| (byte & ~(mc6821[dnr].ddra));
}
void C6821::mc6821_write_prb(BYTE byte, unsigned int dnr)
{
mc6821[dnr].prb = byte;
if (mc6821[dnr].ddrb) // AppleWin:TC
PIA_W_CALLBACK( m_stOutB, mc6821[dnr].prb & mc6821[dnr].ddrb );
}
void C6821::mc6821_write_ddrb(BYTE byte, unsigned int dnr)
{
if (mc6821[dnr].ddrb == byte) // AppleWin:TC
return;
mc6821[dnr].ddrb = byte;
if (mc6821[dnr].ddrb) // AppleWin:TC
PIA_W_CALLBACK( m_stOutB, mc6821[dnr].prb & mc6821[dnr].ddrb );
}
BYTE C6821::mc6821_read_prb(unsigned int dnr)
{
mc6821[dnr].crb = (BYTE)(mc6821[dnr].crb & 0x7f); // AppleWin:TC (Clear IRQ1)
mc6821[dnr].crb = (BYTE)(mc6821[dnr].crb & 0xbf); // AppleWin:TC (Clear IRQ2)
BYTE byte = m_byIB; // AppleWin:TC
return (mc6821[dnr].prb & mc6821[dnr].ddrb)
| (byte & ~(mc6821[dnr].ddrb));
}
void C6821::mc6821_write_cra(BYTE byte, unsigned int dnr)
{
// static BYTE old_cra = 0;
//
// if ((old_cra & 0x38) != (byte & 0x38)) {
//#ifdef MC_DEBUG
// log_debug("MODE %02x", byte & 0x38);
//#endif
// old_cra = byte;
// }
mc6821[dnr].cra = byte;
}
void C6821::mc6821_write_crb(BYTE byte, unsigned int dnr)
{
mc6821[dnr].crb = byte;
}
/*-----------------------------------------------------------------------*/
/* MC6821 signals. */
void C6821::mc6821_set_signal(/*drive_context_t *drive_context,*/ int line)
{
unsigned int dnr = 0;
// dnr = drive_context->mynumber;
switch (line) {
case MC6821_SIG_CA1:
mc6821[dnr].cra = (BYTE)(mc6821[dnr].cra | 0x80);
break;
case MC6821_SIG_CA2:
mc6821[dnr].cra = (BYTE)(mc6821[dnr].cra | 0x40);
break;
case MC6821_SIG_CB1:
mc6821[dnr].crb = (BYTE)(mc6821[dnr].crb | 0x80);
break;
case MC6821_SIG_CB2:
mc6821[dnr].crb = (BYTE)(mc6821[dnr].crb | 0x40);
break;
}
}
/*-----------------------------------------------------------------------*/
/* MC6821 register read/write access. */
void C6821::mc6821_store_internal(WORD addr, BYTE byte, unsigned int dnr)
{
#ifdef MC_DEBUG
log_debug("MC WRITE ADDR: %i DATA:%02x CLK:%i",
addr, byte, drive_clk[dnr]);
#endif
switch (addr) {
case 0: // PIA_DDRA
if (mc6821[dnr].cra & 0x04)
mc6821_write_pra(byte, dnr);
else
mc6821_write_ddra(byte, dnr);
break;
case 1: // PIA_CTLA
mc6821_write_cra(byte, dnr);
break;
case 2: // PIA_DDRB
if (mc6821[dnr].crb & 0x04)
mc6821_write_prb(byte, dnr);
else
mc6821_write_ddrb(byte, dnr);
break;
case 3: // PIA_CTLB
mc6821_write_crb(byte, dnr);
break;
}
}
BYTE C6821::mc6821_read_internal(WORD addr, unsigned int dnr)
{
BYTE tmp = 0;
switch (addr) {
case 0: // PIA_DDRA
if (mc6821[dnr].cra & 0x04)
tmp = mc6821_read_pra(dnr);
else
tmp = mc6821[dnr].ddra;
break;
case 1: // PIA_CTLA
tmp = mc6821[dnr].cra;
break;
case 2: // PIA_DDRB
if (mc6821[dnr].crb & 0x04)
tmp = mc6821_read_prb(dnr);
else
tmp = mc6821[dnr].ddrb;
break;
case 3: // PIA_CTLB
tmp = mc6821[dnr].crb;
break;
}
#ifdef MC_DEBUG
log_debug("MC READ ADDR: %i DATA:%02x CLK:%i",
addr, tmp, drive_clk[dnr]);
#endif
return tmp;
}
void C6821::mc6821_reset_internal(unsigned int dnr)
{
mc6821[dnr].pra = 0;
mc6821[dnr].ddra = 0;
mc6821[dnr].cra = 0;
mc6821[dnr].prb = 0;
mc6821[dnr].ddrb = 0;
mc6821[dnr].crb = 0;
}
/*-----------------------------------------------------------------------*/
//static void REGPARM3 mc6821_store(drive_context_t *drv, WORD addr, BYTE byte)
//{
// mc6821_store_internal((WORD)(addr & 3), byte, drv->mynumber);
//}
//
//static BYTE REGPARM2 mc6821_read(drive_context_t *drv, WORD addr)
//{
// return mc6821_read_internal((WORD)(addr & 3), drv->mynumber);
//}
/*-----------------------------------------------------------------------*/
/* MC6821 external interface. */
/* Functions using drive context. */
void C6821::mc6821_init(/*drive_context_t *drv*/)
{
//mc6821[drv->mynumber].drive = drv->drive;
}
void C6821::mc6821_reset(/*drive_context_t *drv*/)
{
mc6821_reset_internal();
}
//void mc6821_mem_init(struct drive_context_s *drv, unsigned int type)
//{
// drivecpud_context_t *cpud;
//
// cpud = drv->cpud;
//
// /* Setup parallel cable */
// if (type == DRIVE_TYPE_1541 || type == DRIVE_TYPE_1541II
// || type == DRIVE_TYPE_1570 || type == DRIVE_TYPE_1571
// || type == DRIVE_TYPE_1571CR) {
// if (drv->drive->parallel_cable == DRIVE_PC_DD3) {
// drivemem_set_func(cpud, 0x50, 0x60, mc6821_read, mc6821_store);
// }
// }
//}
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