/*
* libtilemcore - Graphing calculator emulation library
*
* Copyright (C) 2009-2011 Benjamin Moody
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see
* .
*/
#ifdef HAVE_CONFIG_H
# include
#endif
#include
#include
#include "tilem.h"
static int certificate_valid(byte* cert)
{
int i, n;
if (cert[0] != 0)
return 0;
i = 1;
/* check that the actual certificate area consists of valid
certificate fields */
while (cert[i] <= 0x0F) {
switch (cert[i + 1] & 0x0F) {
case 0x0D:
n = cert[i + 2] + 3;
break;
case 0x0E:
n = (cert[i + 2] << 8) + cert[i + 3] + 4;
break;
case 0x0F:
n = 6;
break;
default:
n = (cert[i + 1] & 0xf) + 2;
}
i += n;
if (i >= 0x2000)
return 0;
}
/* check that the fields end with FF */
if (cert[i] != 0xFF)
return 0;
/* if there are fields present, assume the certificate is OK */
if (i > 1)
return 1;
/* no fields present -> this could be an incompletely-patched
certificate from an older version of TilEm; verify that the
next 4k bytes are truly empty */
while (i < 0x1000) {
if (cert[i] != 0xFF)
return 0;
i++;
}
return 1;
}
void tilem_calc_fix_certificate(TilemCalc* calc, byte* cert,
int app_start, int app_end,
unsigned exptab_offset)
{
int i, base, max_apps, page;
unsigned insttab_offset = 0x1fe0;
/* If the ROM was dumped from an unpatched OS, the certificate
needs to be patched for some calculator functions to
work. */
/* First, check if the certificate is already valid */
if (cert[0x2000] == 0)
base = 0x2000;
else
base = 0;
if (certificate_valid(cert + base)) {
return;
}
tilem_message(calc, "Repairing certificate area...");
memset(cert, 0xff, 16384);
cert[0] = 0;
cert[insttab_offset] = 0xfe;
if (app_start < app_end)
max_apps = app_end - app_start + 1;
else
max_apps = app_start - app_end + 1;
for (i = 0; i < max_apps; i++) {
if (app_start < app_end)
page = app_start + i;
else
page = app_start - i;
/* Clear installed bit / set expiration count for
existing apps. (If this incorrectly detects pages
that aren't really apps, don't worry about it;
better to err on the side of caution.) */
if (calc->mem[page << 14] != 0x80
|| calc->mem[(page << 14) + 1] != 0x0f)
continue;
tilem_message(calc, "Found application at page %02x (index %d)",
page, i);
cert[insttab_offset + ((i + 1) / 8)] &= ~(1 << ((i + 1) % 8));
cert[exptab_offset + 2 * i] = 0x80;
cert[exptab_offset + 2 * i + 1] = 0x00;
}
}