diff options
| -rw-r--r-- | src/lib/edid.c | 28 |
1 files changed, 21 insertions, 7 deletions
diff --git a/src/lib/edid.c b/src/lib/edid.c index 800ebdd..e5452a5 100644 --- a/src/lib/edid.c +++ b/src/lib/edid.c @@ -23,6 +23,15 @@ #include <stdint.h> +/* + * EDID structure revision 1.1: + * http://en.wikipedia.org/w/index.php?title=Extended_display_identification_data&oldid=46295569 + * + * EDID structure revision 1.3: + * http://en.wikipedia.org/wiki/Extended_display_identification_data + */ + + /** * Parse the EDID of a monitor. * @@ -34,25 +43,30 @@ */ int libgamma_parse_edid(libgamma_crtc_information_t* restrict this, int32_t fields) { -#define __test_version(edid, major, minor) (((edid)[18] == major) && ((edid)[19] == minor)) +#define __test_version(edid, major, minor_min, minor_max) \ + (((edid)[18] == major) && (minor_min <= (edid)[19]) && ((edid)[19] <= minor_max)) #define __m(value) (this->edid[index++] != value) int error = 0; int checksum = 0; size_t i, index = 0; - /* If the length of the EDID is not 128 bytes, we know that it is not of - EDID structure revision 1.3, and thus we do not support it. Additionally + /* If the length of the EDID is not 128 bytes, we know that it is not of EDID + structure revision 1.0–1.3, and thus we do not support it. Additionally this make sure we do not do segmentation violation on the next test. */ if (this->edid_length != 128) error = LIBGAMMA_EDID_LENGTH_UNSUPPORTED; /* Check that the magic number of that of the EDID structure. */ else if (__m(0x00) || __m(0xFF) || __m(0xFF) || __m(0xFF) || __m(0xFF) || __m(0xFF) || __m(0xFF) || __m(0x00)) error = LIBGAMMA_EDID_WRONG_MAGIC_NUMBER; - /* Check that EDID structure revision 1.3 is used, it is the only version - we support. It is also by far the most commonly use revision and it is - currently the newest revision. */ - else if (__test_version(this->edid, 1, 3) == 0) + /* Check that EDID structure revision 1.1–1.3 is used, those are the only + version we support. EDID structure revision 1.3 is also by far the most + commonly use revision and it is currently the newest revision. We know + that parsing works for both revision 1.1 and revision 1.3, because of + this we assume it is also correct for revision 1.2. However, we are not + assuming this for revision 1.0 which appeared in August 1994 and was + replaced by revision 1.1 in April 1996. */ + else if (__test_version(this->edid, 1, 1, 3) == 0) error = LIBGAMMA_EDID_REVISION_UNSUPPORTED; /* If we have encountered an error, report it for the fields that require |