parse edid

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 79 insertions, 0 deletions

diff --git a/src/edid.c b/src/edid.c
new file mode 100644
index 0000000..09b3ef5
--- /dev/null
+++ b/src/edid.c
@@ -0,0 +1,79 @@
+/**
+ * libgamma — Display server abstraction layer for gamma ramp adjustments
+ * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 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 General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "edid.h"
+
+#include "libgamma-method.h"
+#include "libgamma-error.h"
+
+#include <stdint.h>
+
+
+/**
+ * Parse the EDID of a monitor
+ * 
+ * @param   this    Instance of a data structure to fill with the information about the EDID.
+ *                  It must contain the EDID and its length.
+ * @param   feilds  OR:ed identifiers for the information about the EDID that should be parsed.
+ *                  Fields that do not have to do with EDID are ignored.
+ * @return          Non-zero on error
+ */
+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))
+  
+  int error = 0;
+  int checksum = 0;
+  size_t i;
+  
+  if (this->edid_length != 128)
+    error = LIBGAMMA_EDID_LENGTH_UNSUPPORTED;
+  else if ((this->edid[0] != 0x00) || (this->edid[1] != 0xFF) || (this->edid[2] != 0xFF) || (this->edid[3] != 0xFF) ||
+	   (this->edid[4] != 0xFF) || (this->edid[5] != 0xFF) || (this->edid[6] != 0xFF) || (this->edid[7] != 0x00))
+    error = LIBGAMMA_EDID_WRONG_MAGIC_NUMBER;
+  else if (__test_version(this->edid, 1, 3) == 0)
+    error = LIBGAMMA_EDID_REVISION_UNSUPPORTED;
+  
+  this->width_mm_edid_error = this->height_mm_edid_error = this->gamma_error = error;
+  
+  this->width_mm_edid = (size_t)(this->edid[21]) * 10;
+  this->height_mm_edid = (size_t)(this->edid[22]) * 10;
+  
+  if ((fields & CRTC_INFO_GAMMA) && (error == 0))
+    {
+      if (this->edid[23] == 0xFF)
+	this->gamma_error = LIBGAMMA_GAMMA_NOT_SPECIFIED;
+      else
+	this->gamma_red = this->gamma_green = this->gamma_blue = (float)((int)(this->edid[23]) + 100) / 100.f;
+    }
+  
+  if (error == 0)
+    for (i = 0; i < this->edid_length; i++)
+      checksum += (int)(this->edid[i]);
+  if ((checksum & 255))
+    {
+      error = LIBGAMMA_EDID_CHECKSUM_ERROR;
+      this->edid_error = this->width_mm_edid_error = this->height_mm_edid_error = error;
+      this->gamma_error = this->gamma_error == LIBGAMMA_GAMMA_NOT_SPECIFIED
+	? LIBGAMMA_GAMMA_NOT_SPECIFIED_AND_EDID_CHECKSUM_ERROR : 0;
+    }
+  
+  return error | this->gamma_error;
+  
+#undef __test_version
+}
+