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/* ula.c: ULA routines
Copyright (c) 1999-2008 Philip Kendall, Darren Salt
$Id: ula.c 4125 2010-05-06 22:18:50Z pak21 $
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.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
Author contact information:
E-mail: philip-fuse@shadowmagic.org.uk
*/
#include <config.h>
#include <libspectrum.h>
#include "compat.h"
#include "keyboard.h"
#include "loader.h"
#include "machine.h"
#include "module.h"
#include "settings.h"
#include "sound.h"
#include "spectrum.h"
#include "tape.h"
#include "ula.h"
static libspectrum_byte last_byte;
libspectrum_byte ula_contention[ ULA_CONTENTION_SIZE ];
libspectrum_byte ula_contention_no_mreq[ ULA_CONTENTION_SIZE ];
/* What to return if no other input pressed; depends on the last byte
output to the ULA; see CSS FAQ | Technical Information | Port #FE
for full details */
libspectrum_byte ula_default_value;
static void ula_from_snapshot( libspectrum_snap *snap );
static void ula_to_snapshot( libspectrum_snap *snap );
static module_info_t ula_module_info = {
NULL,
NULL,
NULL,
ula_from_snapshot,
ula_to_snapshot,
};
int
ula_init( void )
{
module_register( &ula_module_info );
ula_default_value = 0xff;
return 0;
}
libspectrum_byte
ula_read( libspectrum_word port, int *attached )
{
libspectrum_byte r = ula_default_value;
*attached = 1;
loader_detect_loader();
r &= keyboard_read( port >> 8 );
if( tape_microphone ) r ^= 0x40;
return r;
}
/* What happens when we write to the ULA? */
void
ula_write( libspectrum_word port GCC_UNUSED, libspectrum_byte b )
{
last_byte = b;
display_set_lores_border( b & 0x07 );
sound_beeper( (!!(b & 0x10) << 1) + ( (!(b & 0x8)) | tape_microphone ) );
/* FIXME: shouldn't really be using the memory capabilities here */
if( machine_current->timex ) {
ula_default_value = 0x5f;
} else if( machine_current->capabilities & LIBSPECTRUM_MACHINE_CAPABILITY_PLUS3_MEMORY ) {
ula_default_value = 0xbf;
} else if( machine_current->capabilities & LIBSPECTRUM_MACHINE_CAPABILITY_128_MEMORY || !settings_current.issue2 ) {
/* 128K always acts like an Issue 3 */
ula_default_value = b & 0x10 ? 0xff : 0xbf;
} else {
/* Issue 2 */
ula_default_value = b & 0x18 ? 0xff : 0xbf;
}
}
libspectrum_byte
ula_last_byte( void )
{
return last_byte;
}
libspectrum_byte
ula_tape_level( void )
{
return last_byte & 0x8;
}
static void
ula_from_snapshot( libspectrum_snap *snap )
{
ula_write( 0x00fe, libspectrum_snap_out_ula( snap ) );
tstates = libspectrum_snap_tstates( snap );
settings_current.issue2 = libspectrum_snap_issue2( snap );
}
static void
ula_to_snapshot( libspectrum_snap *snap )
{
libspectrum_snap_set_out_ula( snap, last_byte );
libspectrum_snap_set_tstates( snap, tstates );
libspectrum_snap_set_issue2( snap, settings_current.issue2 );
}
void
ula_contend_port_early( libspectrum_word port )
{
if( memory_map_read[ port >> 13 ].contended )
tstates += ula_contention_no_mreq[ tstates ];
tstates++;
}
void
ula_contend_port_late( libspectrum_word port )
{
if( machine_current->ram.port_from_ula( port ) ) {
tstates += ula_contention_no_mreq[ tstates ]; tstates += 2;
} else {
if( memory_map_read[ port >> 13 ].contended ) {
tstates += ula_contention_no_mreq[ tstates ]; tstates++;
tstates += ula_contention_no_mreq[ tstates ]; tstates++;
tstates += ula_contention_no_mreq[ tstates ];
} else {
tstates += 2;
}
}
}
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