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/* loader.c: loader detection
Copyright (c) 2006 Philip Kendall
$Id: loader.c 3941 2009-01-09 22:38:21Z 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 "event.h"
#include "loader.h"
#include "memory.h"
#include "settings.h"
#include "spectrum.h"
#include "tape.h"
#include "z80/z80.h"
static int successive_reads = 0;
static libspectrum_signed_dword last_tstates_read = -100000;
static libspectrum_byte last_b_read = 0x00;
static int length_known1 = 0, length_known2 = 0;
static int length_long1 = 0, length_long2 = 0;
typedef enum acceleration_mode_t {
ACCELERATION_MODE_NONE = 0,
ACCELERATION_MODE_INCREASING,
ACCELERATION_MODE_DECREASING,
} acceleration_mode_t;
static acceleration_mode_t acceleration_mode;
static size_t acceleration_pc;
void
loader_frame( libspectrum_dword frame_length )
{
if( last_tstates_read > -100000 ) {
last_tstates_read -= frame_length;
}
}
void
loader_tape_play( void )
{
successive_reads = 0;
acceleration_mode = ACCELERATION_MODE_NONE;
}
void
loader_tape_stop( void )
{
successive_reads = 0;
acceleration_mode = ACCELERATION_MODE_NONE;
}
static void
do_acceleration( void )
{
if( length_known1 ) {
int set_b_high = length_long1;
set_b_high ^= ( acceleration_mode == ACCELERATION_MODE_DECREASING );
if( set_b_high ) {
z80.bc.b.h = 0xfe;
} else {
z80.bc.b.h = 0x00;
}
z80.af.b.l |= 0x01;
z80.pc.b.l = readbyte_internal( z80.sp.w ); z80.sp.w++;
z80.pc.b.h = readbyte_internal( z80.sp.w ); z80.sp.w++;
event_remove_type( tape_edge_event );
tape_next_edge( tstates, 0, NULL );
successive_reads = 0;
}
length_known1 = length_known2;
length_long1 = length_long2;
}
static acceleration_mode_t
acceleration_detector( libspectrum_word pc )
{
int state = 0, count = 0;
while( 1 ) {
libspectrum_byte b = readbyte_internal( pc ); pc++; count++;
switch( state ) {
case 0:
switch( b ) {
case 0x04: state = 1; break; /* INC B - Many loaders */
default: state = 13; break; /* Possible Digital Integration */
}
break;
case 1:
switch( b ) {
case 0xc8: state = 2; break; /* RET Z */
default: return ACCELERATION_MODE_NONE;
}
break;
case 2:
switch( b ) {
case 0x3e: state = 3; break; /* LD A,nn */
default: return ACCELERATION_MODE_NONE;
}
break;
case 3:
switch( b ) {
case 0x00: /* Search Loader */
case 0x7f: /* ROM loader and variants */
state = 4; break; /* Data byte */
default: return ACCELERATION_MODE_NONE;
}
break;
case 4:
switch( b ) {
case 0xdb: state = 5; break; /* IN A,(nn) */
default: return ACCELERATION_MODE_NONE;
}
break;
case 5:
switch( b ) {
case 0xfe: state = 6; break; /* Data byte */
default: return ACCELERATION_MODE_NONE;
}
break;
case 6:
switch( b ) {
case 0x1f: state = 7; break; /* RRA */
case 0xa9: state = 24; break; /* XOR C - Search Loader */
default: return ACCELERATION_MODE_NONE;
}
break;
case 7:
switch( b ) {
case 0x00: /* NOP - Bleepload */
case 0xa7: /* AND A - Microsphere */
case 0xc8: /* RET Z - Paul Owens */
case 0xd0: /* RET NC - ROM loader */
state = 8; break;
case 0xa9: state = 9; break; /* XOR C - Speedlock */
default: return ACCELERATION_MODE_NONE;
}
break;
case 8:
switch( b ) {
case 0xa9: state = 9; break; /* XOR C */
default: return ACCELERATION_MODE_NONE;
}
break;
case 9:
switch( b ) {
case 0xe6: state = 10; break; /* AND nn */
default: return ACCELERATION_MODE_NONE;
}
break;
case 10:
switch( b ) {
case 0x20: state = 11; break; /* Data byte */
default: return ACCELERATION_MODE_NONE;
}
break;
case 11:
switch( b ) {
case 0x28: state = 12; break; /* JR nn */
default: return ACCELERATION_MODE_NONE;
}
break;
case 12:
if( b == 0x100 - count ) {
return ACCELERATION_MODE_INCREASING;
} else {
return ACCELERATION_MODE_NONE;
}
break;
/* Digital Integration loader */
case 13:
state = 14; break; /* Possible Digital Integration */
case 14:
switch( b ) {
case 0x05: state = 15; break; /* DEC B - Digital Integration */
default: return ACCELERATION_MODE_NONE;
}
break;
case 15:
switch( b ) {
case 0xc8: state = 16; break; /* RET Z */
default: return ACCELERATION_MODE_NONE;
}
break;
case 16:
switch( b ) {
case 0xdb: state = 17; break; /* IN A,(nn) */
default: return ACCELERATION_MODE_NONE;
}
break;
case 17:
switch( b ) {
case 0xfe: state = 18; break; /* Data byte */
default: return ACCELERATION_MODE_NONE;
}
break;
case 18:
switch( b ) {
case 0xa9: state = 19; break; /* XOR C */
default: return ACCELERATION_MODE_NONE;
}
break;
case 19:
switch( b ) {
case 0xe6: state = 20; break; /* AND nn */
default: return ACCELERATION_MODE_NONE;
}
break;
case 20:
switch( b ) {
case 0x40: state = 21; break; /* Data byte */
default: return ACCELERATION_MODE_NONE;
}
break;
case 21:
switch( b ) {
case 0xca: state = 22; break; /* JP Z,nnnn */
default: return ACCELERATION_MODE_NONE;
}
break;
case 22: /* LSB of jump target */
if( b == ( z80.pc.w - 4 ) % 0x100 ) {
state = 23;
} else {
return ACCELERATION_MODE_NONE;
}
break;
case 23: /* MSB of jump target */
if( b == ( z80.pc.w - 4 ) / 0x100 ) {
return ACCELERATION_MODE_DECREASING;
} else {
return ACCELERATION_MODE_NONE;
}
/* Search loader */
case 24:
switch( b ) {
case 0xe6: state = 25; break; /* AND nn */
default: return ACCELERATION_MODE_NONE;
}
break;
case 25:
switch( b ) {
case 0x40: state = 26; break; /* Data byte */
default: return ACCELERATION_MODE_NONE;
}
break;
case 26:
switch( b ) {
case 0xd8: state = 27; break; /* RET C */
default: return ACCELERATION_MODE_NONE;
}
break;
case 27:
switch( b ) {
case 0x00: state = 11; break; /* NOP */
default: return ACCELERATION_MODE_NONE;
}
break;
default:
/* Can't happen */
break;
}
}
}
static void
check_for_acceleration( void )
{
/* If the IN occured at a different location to the one we're
accelerating, stop acceleration */
if( acceleration_mode && z80.pc.w != acceleration_pc )
acceleration_mode = ACCELERATION_MODE_NONE;
/* If we're not accelerating, check if this is a loader */
if( !acceleration_mode ) {
acceleration_mode = acceleration_detector( z80.pc.w - 6 );
acceleration_pc = z80.pc.w;
}
if( acceleration_mode ) do_acceleration();
}
void
loader_detect_loader( void )
{
libspectrum_dword tstates_diff = tstates - last_tstates_read;
libspectrum_byte b_diff = z80.bc.b.h - last_b_read;
last_tstates_read = tstates;
last_b_read = z80.bc.b.h;
if( settings_current.detect_loader ) {
if( tape_is_playing() ) {
if( tstates_diff > 1000 || ( b_diff != 1 && b_diff != 0 &&
b_diff != 0xff ) ) {
successive_reads++;
if( successive_reads >= 2 ) {
tape_stop();
}
} else {
successive_reads = 0;
}
} else {
if( tstates_diff <= 500 && ( b_diff == 1 || b_diff == 0xff ) ) {
successive_reads++;
if( successive_reads >= 10 ) {
tape_do_play( 1 );
}
} else {
successive_reads = 0;
}
}
} else {
successive_reads = 0;
}
if( settings_current.accelerate_loader && tape_is_playing() )
check_for_acceleration();
}
void
loader_set_acceleration_flags( int flags )
{
if( flags & LIBSPECTRUM_TAPE_FLAGS_LENGTH_SHORT ) {
length_known2 = 1;
length_long2 = 0;
} else if( flags & LIBSPECTRUM_TAPE_FLAGS_LENGTH_LONG ) {
length_known2 = 1;
length_long2 = 1;
} else {
length_known2 = 0;
}
}
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