1 /* biossums.c --- written by Eike W. for the Bochs BIOS */
2 /* adapted for the LGPL'd VGABIOS by vruppert */
7 typedef unsigned char byte
;
9 void check( int value
, char* message
);
11 #define LEN_BIOS_DATA 0x8000
12 #define MAX_OFFSET (LEN_BIOS_DATA - 1)
15 #define BIOS_OFFSET 0x7FFF
17 long chksum_bios_get_offset( byte
* data
, long offset
);
18 byte
chksum_bios_calc_value( byte
* data
, long offset
);
19 byte
chksum_bios_get_value( byte
* data
, long offset
);
20 void chksum_bios_set_value( byte
* data
, long offset
, byte value
);
24 #define PMID_CHKSUM 19
26 long chksum_pmid_get_offset( byte
* data
, long offset
);
27 byte
chksum_pmid_calc_value( byte
* data
, long offset
);
28 byte
chksum_pmid_get_value( byte
* data
, long offset
);
29 void chksum_pmid_set_value( byte
* data
, long offset
, byte value
);
32 byte bios_data
[LEN_BIOS_DATA
];
35 int main( int argc
, char* argv
[] ) {
38 long offset
, tmp_offset
;
39 byte cur_val
= 0, new_val
= 0;
44 printf( "Error. Need a file-name as an argument.\n" );
48 if(( stream
= fopen( argv
[1], "rb" )) == NULL
) {
49 printf( "Error opening %s for reading.\n", argv
[1] );
52 if( fread( bios_data
, 1, LEN_BIOS_DATA
, stream
) >= LEN_BIOS_DATA
) {
53 printf( "Error reading max. 32767 Bytes from %s.\n", argv
[1] );
61 while( (tmp_offset
= chksum_pmid_get_offset( bios_data
, offset
)) != -1L ) {
63 cur_val
= chksum_pmid_get_value( bios_data
, offset
);
64 new_val
= chksum_pmid_calc_value( bios_data
, offset
);
65 printf( "\nPMID entry at: 0x%4lX\n", offset
);
66 printf( "Current checksum: 0x%02X\n", cur_val
);
67 printf( "Calculated checksum: 0x%02X ", new_val
);
70 if( hits
== 1 && cur_val
!= new_val
) {
71 printf( "Setting checksum." );
72 chksum_pmid_set_value( bios_data
, offset
, new_val
);
75 printf( "Multiple PMID entries! No checksum set." );
83 offset
= chksum_bios_get_offset( bios_data
, offset
);
84 cur_val
= chksum_bios_get_value( bios_data
, offset
);
85 new_val
= chksum_bios_calc_value( bios_data
, offset
);
86 printf( "\nBios checksum at: 0x%4lX\n", offset
);
87 printf( "Current checksum: 0x%02X\n", cur_val
);
88 printf( "Calculated checksum: 0x%02X ", new_val
);
89 if( cur_val
!= new_val
) {
90 printf( "Setting checksum." );
91 chksum_bios_set_value( bios_data
, offset
, new_val
);
96 if(( stream
= fopen( argv
[1], "wb" )) == NULL
) {
97 printf( "Error opening %s for writing.\n", argv
[1] );
100 if( fwrite( bios_data
, 1, LEN_BIOS_DATA
, stream
) < LEN_BIOS_DATA
) {
101 printf( "Error writing 32KBytes to %s.\n", argv
[1] );
103 exit( EXIT_FAILURE
);
107 return( EXIT_SUCCESS
);
111 void check( int okay
, char* message
) {
114 printf( "\n\nError. %s.\n", message
);
115 exit( EXIT_FAILURE
);
120 long chksum_bios_get_offset( byte
* data
, long offset
) {
122 return( BIOS_OFFSET
);
126 byte
chksum_bios_calc_value( byte
* data
, long offset
) {
132 for( i
= 0; i
< MAX_OFFSET
; i
++ ) {
133 sum
= sum
+ *( data
+ i
);
135 sum
= -sum
; /* iso ensures -s + s == 0 on unsigned types */
140 byte
chksum_bios_get_value( byte
* data
, long offset
) {
142 return( *( data
+ BIOS_OFFSET
) );
146 void chksum_bios_set_value( byte
* data
, long offset
, byte value
) {
148 *( data
+ BIOS_OFFSET
) = value
;
152 byte
chksum_pmid_calc_value( byte
* data
, long offset
) {
159 check( offset
+ len
<= MAX_OFFSET
, "PMID entry length out of bounds" );
161 for( i
= 0; i
< len
; i
++ ) {
162 if( i
!= PMID_CHKSUM
) {
163 sum
= sum
+ *( data
+ offset
+ i
);
171 long chksum_pmid_get_offset( byte
* data
, long offset
) {
175 while( offset
+ PMID_LEN
< MAX_OFFSET
) {
177 if( *( data
+ offset
+ 0 ) == 'P' && \
178 *( data
+ offset
+ 1 ) == 'M' && \
179 *( data
+ offset
+ 2 ) == 'I' && \
180 *( data
+ offset
+ 3 ) == 'D' ) {
189 byte
chksum_pmid_get_value( byte
* data
, long offset
) {
191 check( offset
+ PMID_CHKSUM
<= MAX_OFFSET
, "PMID checksum out of bounds" );
192 return( *( data
+ offset
+ PMID_CHKSUM
) );
196 void chksum_pmid_set_value( byte
* data
, long offset
, byte value
) {
198 check( offset
+ PMID_CHKSUM
<= MAX_OFFSET
, "PMID checksum out of bounds" );
199 *( data
+ offset
+ PMID_CHKSUM
) = value
;