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/*
dsspec - Nintendo DS Sinclair Spectrum 48K emulator.
Copyright (C) 2006 Ian Cowburn
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.
$Id$
*/
#include "snap.h"
/* ---------------------------------------- MACROS
*/
#ifndef TRUE
#define TRUE 1
#endif
#ifndef FALSE
#define FALSE 0
#endif
#define ROMLEN 0x4000
/* ---------------------------------------- PRIVATE DATA
*/
static Z80Byte *tap_file;
static int tap_len;
static int tap_ptr;
/* ---------------------------------------- PRIVATE FUNCTIONS
*/
static Z80Byte GetByte(void)
{
Z80Byte ret=0;
if (tap_len)
{
ret=tap_file[tap_ptr];
tap_ptr=(tap_ptr+1)%tap_len;
}
return ret;
}
static Z80Word GetLSBWord(void)
{
int c1,c2;
c1=GetByte();
c2=GetByte();
return c1+(c2<<8);
}
/* ---------------------------------------- INTERFACES
*/
void TAPSetTape(Z80Byte *tape, int len)
{
tap_file = tape;
tap_len = len;
tap_ptr = 0;
}
int TAPLoad(Z80Byte id, Z80Word *addr, Z80Word *len, SNAP_Poke poke)
{
Z80Word blen;
Z80Byte type,b,csum,tape_csum;
if (!tap_file)
{
return FALSE;
}
b=0;
blen=GetLSBWord();
type=GetByte();
csum=id;
/* Have we found the requested block?
*/
if (id==type)
{
/* Knock of block type
*/
blen--;
while(blen && *len)
{
b=GetByte();
csum^=b;
poke(*addr,b);
(*addr)++;
(*len)--;
blen--;
}
/* Get the checksum
*/
if (blen)
{
tape_csum=GetByte();
blen--;
}
else
tape_csum=b;
/* In case we've been request less bytes than the block size
*/
while(blen--)
GetByte();
/* Check the checksum
*/
return csum==tape_csum;
}
else
{
/* If it's the wrong type, skip it
*/
while(blen--)
GetByte();
return FALSE;
}
}
/* END OF FILE */
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