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/* plusd.c: Routines for handling DISCiPLE/+D snapshots
Copyright (c) 1998,2003 Philip Kendall
Copyright (c) 2007,2015 Stuart Brady
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 <string.h>
#include "internals.h"
#define PLUSD_HEADER_LENGTH 22
static libspectrum_error
identify_machine( size_t buffer_length, libspectrum_snap *snap );
static libspectrum_error
libspectrum_plusd_read_header( const libspectrum_byte *buffer,
size_t buffer_length, libspectrum_snap *snap );
static libspectrum_error
libspectrum_plusd_read_data( const libspectrum_byte *buffer,
libspectrum_snap *snap );
static libspectrum_byte
readbyte( libspectrum_snap *snap, libspectrum_word address );
static void
libspectrum_plusd_read_128_data( libspectrum_snap *snap,
const libspectrum_byte *buffer );
libspectrum_error
libspectrum_plusd_read( libspectrum_snap *snap, const libspectrum_byte *buffer,
size_t buffer_length )
{
int error;
error = identify_machine( buffer_length, snap );
if( error != LIBSPECTRUM_ERROR_NONE ) return error;
error = libspectrum_plusd_read_header( buffer, buffer_length, snap );
if( error != LIBSPECTRUM_ERROR_NONE ) return error;
buffer += PLUSD_HEADER_LENGTH;
error = libspectrum_plusd_read_data( buffer, snap );
if( error != LIBSPECTRUM_ERROR_NONE ) return error;
return LIBSPECTRUM_ERROR_NONE;
}
static libspectrum_error
identify_machine( size_t buffer_length, libspectrum_snap *snap )
{
switch( buffer_length ) {
case PLUSD_HEADER_LENGTH + 0xc000:
libspectrum_snap_set_machine( snap, LIBSPECTRUM_MACHINE_48 );
break;
case PLUSD_HEADER_LENGTH + 1 + 0x20000:
libspectrum_snap_set_machine( snap, LIBSPECTRUM_MACHINE_128 );
break;
default:
libspectrum_print_error( LIBSPECTRUM_ERROR_CORRUPT,
"plusd identify_machine: unknown length" );
return LIBSPECTRUM_ERROR_CORRUPT;
}
return LIBSPECTRUM_ERROR_NONE;
}
static libspectrum_error
libspectrum_plusd_read_header( const libspectrum_byte *buffer,
size_t buffer_length, libspectrum_snap *snap )
{
libspectrum_byte i;
libspectrum_snap_set_iy ( snap, buffer[ 0] + buffer[ 1] * 0x100 );
libspectrum_snap_set_ix ( snap, buffer[ 2] + buffer[ 3] * 0x100 );
libspectrum_snap_set_de_( snap, buffer[ 4] + buffer[ 5] * 0x100 );
libspectrum_snap_set_bc_( snap, buffer[ 6] + buffer[ 7] * 0x100 );
libspectrum_snap_set_hl_( snap, buffer[ 8] + buffer[ 9] * 0x100 );
libspectrum_snap_set_f_ ( snap, buffer[10] );
libspectrum_snap_set_a_ ( snap, buffer[11] );
libspectrum_snap_set_de ( snap, buffer[12] + buffer[13] * 0x100 );
libspectrum_snap_set_bc ( snap, buffer[14] + buffer[15] * 0x100 );
libspectrum_snap_set_hl ( snap, buffer[16] + buffer[17] * 0x100 );
/* Header offset 18 is 'rubbish' */
i = buffer[19]; libspectrum_snap_set_i( snap, i );
libspectrum_snap_set_sp ( snap, buffer[20] + buffer[21] * 0x100 );
/* Make a guess at the interrupt mode depending on what I was set to */
libspectrum_snap_set_im( snap, ( i == 0 || i == 63 ) ? 1 : 2 );
return LIBSPECTRUM_ERROR_NONE;
}
static libspectrum_error
libspectrum_plusd_read_data( const libspectrum_byte *buffer,
libspectrum_snap *snap )
{
libspectrum_byte iff;
libspectrum_word sp;
int error;
sp = libspectrum_snap_sp( snap );
/* We must have 0x4000 <= SP <= 0xfffa so we can rescue the stacked
registers */
if( sp < 0x4000 || sp > 0xfffa ) {
libspectrum_print_error(
LIBSPECTRUM_ERROR_CORRUPT,
"libspectrum_plusd_read_data: SP invalid (0x%04x)", sp
);
return LIBSPECTRUM_ERROR_CORRUPT;
}
switch( libspectrum_snap_machine( snap ) ) {
case LIBSPECTRUM_MACHINE_48:
/* Split the RAM into separate pages */
error = libspectrum_split_to_48k_pages( snap, buffer );
if( error != LIBSPECTRUM_ERROR_NONE ) return error;
break;
case LIBSPECTRUM_MACHINE_128:
libspectrum_snap_set_out_128_memoryport( snap, buffer[0] );
buffer++;
libspectrum_plusd_read_128_data( snap, buffer );
break;
default:
libspectrum_print_error( LIBSPECTRUM_ERROR_LOGIC,
"libspectrum_plusd_read_data: unknown machine" );
return LIBSPECTRUM_ERROR_LOGIC;
}
/* R, IFF, AF and PC are stored on the stack */
iff = readbyte( snap, sp ) & 0x04;
libspectrum_snap_set_r ( snap, readbyte( snap, sp + 1 ) );
libspectrum_snap_set_iff1( snap, iff );
libspectrum_snap_set_iff2( snap, iff );
libspectrum_snap_set_f ( snap, readbyte( snap, sp + 2 ) );
libspectrum_snap_set_a ( snap, readbyte( snap, sp + 3 ) );
libspectrum_snap_set_pc ( snap, readbyte( snap, sp + 4 ) +
readbyte( snap, sp + 5 ) * 0x100 );
/* Store SP + 6 to account for those unstacked values */
libspectrum_snap_set_sp( snap, sp + 6 );
return LIBSPECTRUM_ERROR_NONE;
}
static libspectrum_byte
readbyte( libspectrum_snap *snap, libspectrum_word address )
{
int page;
switch( address >> 14 ) {
case 1:
page = 5;
break;
case 2:
page = 2;
break;
case 3:
page = libspectrum_snap_out_128_memoryport( snap ) & 0x07;
break;
default:
return 0;
}
return libspectrum_snap_pages( snap, page )[ address & 0x3fff ];
}
static void
libspectrum_plusd_read_128_data( libspectrum_snap *snap,
const libspectrum_byte *buffer )
{
int i;
for( i=0; i<8; i++ ) {
libspectrum_byte *ram;
ram = libspectrum_new( libspectrum_byte, 0x4000 );
libspectrum_snap_set_pages( snap, i, ram );
memcpy( ram, buffer, 0x4000 );
buffer += 0x4000;
}
}
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