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/* am29f010.c 1Mbit flash chip emulation
Emulates the AMD 29F010 flash chip
Copyright (c) 2011-2015 Guesser, Philip Kendall
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.
*/
#include <config.h>
#include <string.h>
#include "am29f010.h"
#include "fuse.h"
#include "ui/ui.h"
#define SIZE_OF_FLASH_ROM 0x20000 /* 128kB */
#define SIZE_OF_FLASH_PAGE 0x4000 /* 16kB */
typedef enum am29f010_flash_state {
FLASH_STATE_RESET,
FLASH_STATE_CYCLE2,
FLASH_STATE_CYCLE3,
FLASH_STATE_CYCLE4,
FLASH_STATE_CYCLE5,
FLASH_STATE_CYCLE6,
FLASH_STATE_PROGRAM,
} am29f010_flash_state;
struct flash_am29f010_t {
am29f010_flash_state flash_state;
libspectrum_byte *memory;
};
flash_am29f010_t*
flash_am29f010_alloc( void )
{
return libspectrum_new( flash_am29f010_t, 1 );
}
void
flash_am29f010_free( flash_am29f010_t *self )
{
libspectrum_free( self );
}
void
flash_am29f010_init( flash_am29f010_t *self, libspectrum_byte *memory )
{
self->flash_state = FLASH_STATE_RESET;
self->memory = memory;
}
static void
flash_am29f010_chip_erase( flash_am29f010_t *self )
{
memset( self->memory, 0xff, SIZE_OF_FLASH_ROM );
}
static void
flash_am29f010_sector_erase( flash_am29f010_t *self, libspectrum_byte page )
{
memset( self->memory + ( page * SIZE_OF_FLASH_PAGE ), 0xff, SIZE_OF_FLASH_PAGE );
}
static void
flash_am29f010_program( flash_am29f010_t *self, libspectrum_byte page, libspectrum_word address, libspectrum_byte b )
{
libspectrum_dword flash_offset = page * SIZE_OF_FLASH_PAGE + address;
self->memory[ flash_offset ] = b;
}
void
flash_am29f010_write( flash_am29f010_t *self, libspectrum_byte page, libspectrum_word address, libspectrum_byte b )
{
libspectrum_word flash_address = address & 0xfff;
/* We implement only the reset, program, chip erase and sector erase
commands for now */
switch (self->flash_state) {
case FLASH_STATE_RESET:
if( flash_address == 0x555 && b == 0xaa )
self->flash_state = FLASH_STATE_CYCLE2;
break;
case FLASH_STATE_CYCLE2:
if( flash_address == 0x2aa && b == 0x55 )
self->flash_state = FLASH_STATE_CYCLE3;
break;
case FLASH_STATE_CYCLE3:
if( flash_address == 0x555 ) {
if( b == 0xa0 )
self->flash_state = FLASH_STATE_PROGRAM;
else if( b == 0x80 )
self->flash_state = FLASH_STATE_CYCLE4;
}
break;
case FLASH_STATE_CYCLE4:
if( flash_address == 0x555 && b == 0xaa )
self->flash_state = FLASH_STATE_CYCLE5;
break;
case FLASH_STATE_CYCLE5:
if( flash_address == 0x2aa && b == 0x55 )
self->flash_state = FLASH_STATE_CYCLE6;
break;
case FLASH_STATE_CYCLE6:
if( flash_address == 0x555 && b == 0x10 ) {
flash_am29f010_chip_erase( self );
self->flash_state = FLASH_STATE_RESET;
} else if( b == 0x30 ) {
flash_am29f010_sector_erase( self, page );
self->flash_state = FLASH_STATE_RESET;
}
break;
case FLASH_STATE_PROGRAM:
flash_am29f010_program( self, page, address, b );
self->flash_state = FLASH_STATE_RESET;
break;
}
if( b == 0x0f )
self->flash_state = FLASH_STATE_RESET;
}
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