/* biossums.c --- written by Eike W. for the Bochs BIOS */
/* adapted for the LGPL'd VGABIOS by vruppert */
/* 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 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
typedef unsigned char byte;
void check( int value, char* message );
#define MAX_BIOS_DATA 0x10000
long chksum_bios_get_offset( byte* data, long offset );
byte chksum_bios_calc_value( byte* data, long offset );
byte chksum_bios_get_value( byte* data, long offset );
void chksum_bios_set_value( byte* data, long offset, byte value );
#define PMID_LEN 20
#define PMID_CHKSUM 19
long chksum_pmid_get_offset( byte* data, long offset );
byte chksum_pmid_calc_value( byte* data, long offset );
byte chksum_pmid_get_value( byte* data, long offset );
void chksum_pmid_set_value( byte* data, long offset, byte value );
#define PCIR_LEN 24
long chksum_pcir_get_offset( byte* data, long offset );
byte bios_data[MAX_BIOS_DATA];
long bios_len;
int main(int argc, char* argv[])
{
FILE* stream;
long offset, tmp_offset, pcir_offset;
byte bios_len_byte, cur_val = 0, new_val = 0;
int hits, modified;
if (argc != 2) {
printf( "Error. Need a file-name as an argument.\n" );
exit( EXIT_FAILURE );
}
if ((stream = fopen(argv[1], "rb")) == NULL) {
printf("Error opening %s for reading.\n", argv[1]);
exit(EXIT_FAILURE);
}
memset(bios_data, 0, MAX_BIOS_DATA);
bios_len = fread(bios_data, 1, MAX_BIOS_DATA, stream);
if (bios_len > MAX_BIOS_DATA) {
printf("Error reading max. 65536 Bytes from %s.\n", argv[1]);
fclose(stream);
exit(EXIT_FAILURE);
}
fclose(stream);
modified = 0;
if (bios_len < 0x8000) {
bios_len = 0x8000;
modified = 1;
} else if ((bios_len & 0x1FF) != 0) {
bios_len = (bios_len + 0x200) & ~0x1FF;
modified = 1;
}
bios_len_byte = (byte)(bios_len / 512);
if (bios_len_byte != bios_data[2]) {
if (modified == 0) {
bios_len += 0x200;
}
bios_data[2] = (byte)(bios_len / 512);
modified = 1;
}
hits = 0;
offset = 0L;
while( (tmp_offset = chksum_pmid_get_offset( bios_data, offset )) != -1L ) {
offset = tmp_offset;
cur_val = chksum_pmid_get_value( bios_data, offset );
new_val = chksum_pmid_calc_value( bios_data, offset );
printf( "\nPMID entry at: 0x%4lX\n", offset );
printf( "Current checksum: 0x%02X\n", cur_val );
printf( "Calculated checksum: 0x%02X ", new_val );
hits++;
}
if ((hits == 1) && (cur_val != new_val)) {
printf("Setting checksum.");
chksum_pmid_set_value( bios_data, offset, new_val );
if (modified == 0) {
bios_len += 0x200;
bios_data[2]++;
}
modified = 1;
}
if (hits >= 2) {
printf( "Multiple PMID entries! No checksum set." );
}
if (hits) {
printf("\n");
}
offset = 0L;
pcir_offset = chksum_pcir_get_offset( bios_data, offset );
if (pcir_offset != -1L) {
if (bios_data[pcir_offset + 16] != bios_data[2]) {
bios_data[pcir_offset + 16] = bios_data[2];
if (modified == 0) {
bios_len += 0x200;
bios_data[2]++;
bios_data[pcir_offset + 16]++;
}
modified = 1;
}
}
offset = 0L;
do {
offset = chksum_bios_get_offset(bios_data, offset);
cur_val = chksum_bios_get_value(bios_data, offset);
new_val = chksum_bios_calc_value(bios_data, offset);
if ((cur_val != new_val) && (modified == 0)) {
bios_len += 0x200;
bios_data[2]++;
if (pcir_offset != -1L) {
bios_data[pcir_offset + 16]++;
}
modified = 1;
} else {
printf("\nBios checksum at: 0x%4lX\n", offset);
printf("Current checksum: 0x%02X\n", cur_val);
printf("Calculated checksum: 0x%02X ", new_val);
if (cur_val != new_val) {
printf("Setting checksum.");
chksum_bios_set_value(bios_data, offset, new_val);
cur_val = new_val;
modified = 1;
}
printf( "\n" );
}
} while (cur_val != new_val);
if (modified == 1) {
if ((stream = fopen( argv[1], "wb")) == NULL) {
printf("Error opening %s for writing.\n", argv[1]);
exit(EXIT_FAILURE);
}
if (fwrite(bios_data, 1, bios_len, stream) < bios_len) {
printf("Error writing %d KBytes to %s.\n", bios_len / 1024, argv[1]);
fclose(stream);
exit(EXIT_FAILURE);
}
fclose(stream);
}
return (EXIT_SUCCESS);
}
void check( int okay, char* message ) {
if( !okay ) {
printf( "\n\nError. %s.\n", message );
exit( EXIT_FAILURE );
}
}
long chksum_bios_get_offset( byte* data, long offset ) {
return (bios_len - 1);
}
byte chksum_bios_calc_value( byte* data, long offset ) {
int i;
byte sum;
sum = 0;
for( i = 0; i < offset; i++ ) {
sum = sum + *( data + i );
}
sum = -sum; /* iso ensures -s + s == 0 on unsigned types */
return( sum );
}
byte chksum_bios_get_value( byte* data, long offset ) {
return( *( data + offset ) );
}
void chksum_bios_set_value( byte* data, long offset, byte value ) {
*( data + offset ) = value;
}
byte chksum_pmid_calc_value( byte* data, long offset ) {
int i;
int len;
byte sum;
len = PMID_LEN;
check((offset + len) <= (bios_len - 1), "PMID entry length out of bounds" );
sum = 0;
for( i = 0; i < len; i++ ) {
if( i != PMID_CHKSUM ) {
sum = sum + *( data + offset + i );
}
}
sum = -sum;
return( sum );
}
long chksum_pmid_get_offset( byte* data, long offset ) {
long result = -1L;
while ((offset + PMID_LEN) < (bios_len - 1)) {
offset = offset + 1;
if( *( data + offset + 0 ) == 'P' && \
*( data + offset + 1 ) == 'M' && \
*( data + offset + 2 ) == 'I' && \
*( data + offset + 3 ) == 'D' ) {
result = offset;
break;
}
}
return( result );
}
byte chksum_pmid_get_value( byte* data, long offset ) {
check((offset + PMID_CHKSUM) <= (bios_len - 1), "PMID checksum out of bounds" );
return( *( data + offset + PMID_CHKSUM ) );
}
void chksum_pmid_set_value( byte* data, long offset, byte value ) {
check((offset + PMID_CHKSUM) <= (bios_len - 1), "PMID checksum out of bounds" );
*( data + offset + PMID_CHKSUM ) = value;
}
long chksum_pcir_get_offset( byte* data, long offset ) {
long result = -1L;
while ((offset + PCIR_LEN) < (bios_len - 1)) {
offset = offset + 1;
if( *( data + offset + 0 ) == 'P' && \
*( data + offset + 1 ) == 'C' && \
*( data + offset + 2 ) == 'I' && \
*( data + offset + 3 ) == 'R' ) {
result = offset;
break;
}
}
return( result );
}