141 lines
3.0 KiB
C
141 lines
3.0 KiB
C
|
|
/* edid.c: retrieve EDID record from raw DDC1 data stream: data
|
|
* is contained in an array of unsigned int each unsigned int
|
|
* contains one bit if bit is 0 unsigned int has to be zero else
|
|
* unsigned int > 0
|
|
*
|
|
* Copyright 1998 by Egbert Eich <Egbert.Eich@Physik.TU-Darmstadt.DE>
|
|
*/
|
|
#ifdef HAVE_XORG_CONFIG_H
|
|
#include <xorg-config.h>
|
|
#endif
|
|
|
|
#include "misc.h"
|
|
#include "xf86.h"
|
|
#include "xf86_OSproc.h"
|
|
#include "xf86DDC.h"
|
|
#include "ddcPriv.h"
|
|
#include <string.h>
|
|
|
|
static int find_start(unsigned int *);
|
|
static unsigned char * find_header(unsigned char *);
|
|
static unsigned char * resort(unsigned char *);
|
|
|
|
unsigned char *
|
|
GetEDID_DDC1(unsigned int *s_ptr)
|
|
{
|
|
unsigned char *d_block, *d_pos;
|
|
unsigned int *s_pos, *s_end;
|
|
int s_start;
|
|
int i,j;
|
|
s_start = find_start(s_ptr);
|
|
if (s_start==-1) return NULL;
|
|
s_end = s_ptr + NUM;
|
|
s_pos = s_ptr + s_start;
|
|
d_block=xalloc(EDID1_LEN);
|
|
if (!d_block) return NULL;
|
|
d_pos = d_block;
|
|
for (i=0;i<EDID1_LEN;i++) {
|
|
for (j=0;j<8;j++) {
|
|
*d_pos <<= 1;
|
|
if (*s_pos) {
|
|
*d_pos |= 0x01;
|
|
}
|
|
s_pos++; if (s_pos == s_end) s_pos=s_ptr;
|
|
};
|
|
s_pos++; if (s_pos == s_end) s_pos=s_ptr;
|
|
d_pos++;
|
|
}
|
|
xfree(s_ptr);
|
|
if (d_block && DDC_checksum(d_block,EDID1_LEN)) return NULL;
|
|
return (resort(d_block));
|
|
}
|
|
|
|
int
|
|
DDC_checksum(unsigned char *block, int len)
|
|
{
|
|
int i, result = 0;
|
|
int not_null = 0;
|
|
|
|
for (i=0;i<len;i++) {
|
|
not_null |= block[i];
|
|
result += block[i];
|
|
}
|
|
|
|
#ifdef DEBUG
|
|
if (result & 0xFF) ErrorF("DDC checksum not correct\n");
|
|
if (!not_null) ErrorF("DDC read all Null\n");
|
|
#endif
|
|
|
|
/* catch the trivial case where all bytes are 0 */
|
|
if (!not_null) return 1;
|
|
|
|
return (result&0xFF);
|
|
}
|
|
|
|
static int
|
|
find_start(unsigned int *ptr)
|
|
{
|
|
unsigned int comp[9], test[9];
|
|
int i,j;
|
|
|
|
for (i=0;i<9;i++){
|
|
comp[i] = *(ptr++);
|
|
test[i] = 1;
|
|
}
|
|
for (i=0;i<127;i++){
|
|
for (j=0;j<9;j++){
|
|
test[j] = test[j] & !(comp[j] ^ *(ptr++));
|
|
}
|
|
}
|
|
for (i=0;i<9;i++)
|
|
if (test[i]) return (i+1);
|
|
return (-1);
|
|
}
|
|
|
|
static unsigned char *
|
|
find_header(unsigned char *block)
|
|
{
|
|
unsigned char *ptr, *head_ptr, *end;
|
|
unsigned char header[]={0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00};
|
|
|
|
ptr = block;
|
|
end = block + EDID1_LEN;
|
|
while (ptr<end) {
|
|
int i;
|
|
head_ptr = ptr;
|
|
for (i=0;i<8;i++){
|
|
if (header[i] != *(head_ptr++)) break;
|
|
if (head_ptr == end) head_ptr = block;
|
|
}
|
|
if (i==8) break;
|
|
ptr++;
|
|
}
|
|
if (ptr == end) return (NULL);
|
|
return (ptr);
|
|
}
|
|
|
|
static unsigned char *
|
|
resort(unsigned char *s_block)
|
|
{
|
|
unsigned char *d_new, *d_ptr, *d_end, *s_ptr, *s_end;
|
|
unsigned char tmp;
|
|
|
|
s_end = s_block + EDID1_LEN;
|
|
d_new = xalloc(EDID1_LEN);
|
|
if (!d_new) return NULL;
|
|
d_end = d_new + EDID1_LEN;
|
|
|
|
s_ptr = find_header(s_block);
|
|
if (!s_ptr) return NULL;
|
|
for (d_ptr=d_new;d_ptr<d_end;d_ptr++){
|
|
tmp = *(s_ptr++);
|
|
*d_ptr = tmp;
|
|
if (s_ptr == s_end) s_ptr = s_block;
|
|
}
|
|
xfree(s_block);
|
|
return (d_new);
|
|
}
|
|
|
|
|