--- edid-decode.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/edid-decode.c b/edid-decode.c
index 15660dc..95e9c96 100644
--- a/edid-decode.c
+++ b/edid-decode.c
@@ -50,6 +50,8 @@ static int name_descriptor_terminated = 0;
static int has_range_descriptor = 0;
static int has_preferred_timing = 0;
static int has_valid_checksum = 1;
+static int has_valid_cea_checksum = 1;
+static int has_valid_displayid_checksum = 1;
static int has_valid_cvt = 1;
static int has_valid_dummy_block = 1;
static int has_valid_week = 0;
@@ -1289,7 +1291,7 @@ parse_cea(unsigned char *x)
detailed_block(detailed, 1);
} while (0);
- do_checksum(x, EDID_PAGE_SIZE);
+ has_valid_cea_checksum = do_checksum(x, EDID_PAGE_SIZE);
return ret;
}
@@ -1380,7 +1382,11 @@ parse_displayid(unsigned char *x)
int i;
printf("Length %d, version %d, extension count %d\n", length, version,
ext_count);
- do_checksum(x+1, length + 5);
+ /* DisplayID length field is number of following bytes
+ * but checksum is calculated over the entire structure
+ * (excluding DisplayID-in-EDID magic byte)
+ */
+ has_valid_displayid_checksum = do_checksum(x+1, length + 5);
int offset = 5;
while (length > 0) {
@@ -2048,7 +2054,7 @@ int main(int argc, char **argv)
has_valid_extension_count = 1;
}
- do_checksum(edid, EDID_PAGE_SIZE);
+ has_valid_checksum = do_checksum(edid, EDID_PAGE_SIZE);
x = edid;
for (edid_lines /= 8; edid_lines > 1; edid_lines--) {
@@ -2142,6 +2148,15 @@ int main(int argc, char **argv)
printf("\tEDID 1.4 block does not set max dotclock\n");
}
+ if (!has_valid_cea_checksum) {
+ printf("CEA extension block does not conform\n");
+ printf("\tBlock has broken checksum\n");
+ }
+ if (!has_valid_displayid_checksum) {
+ printf("DisplayID extension block does not conform\n");
+ printf("\tBlock has broken checksum\n");
+ }
+
if (warning_excessive_dotclock_correction)
printf("Warning: CVT block corrects dotclock by more than 9.75MHz\n");
if (warning_zero_preferred_refresh)
--
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+44 7855 790184
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