parse edid

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

5 files changed, 163 insertions, 8 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
+}
+
diff --git a/src/edid.h b/src/edid.h
new file mode 100644
index 0000000..321a7df
--- /dev/null
+++ b/src/edid.h
@@ -0,0 +1,39 @@
+/**
+ * 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/>.
+ */
+#ifndef LIBGAMMA_EDID_H
+#define LIBGAMMA_EDID_H
+
+#include "libgamma-method.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 out, int32_t fields);
+
+
+#endif
+
diff --git a/src/gamma-linux-drm.c b/src/gamma-linux-drm.c
index 9539700..4ac0022 100644
--- a/src/gamma-linux-drm.c
+++ b/src/gamma-linux-drm.c
@@ -24,6 +24,7 @@
 #include "gamma-linux-drm.h"
 
 #include "libgamma-error.h"
+#include "edid.h"
 
 #include <limits.h>
 #include <stdlib.h>
@@ -660,10 +661,10 @@ int libgamma_linux_drm_get_crtc_information(libgamma_crtc_information_t* restric
   if ((connector = find_connector(crtc, &error)) == NULL)
     {
       e |= this->width_mm_error      = this->height_mm_error
-	= this->connector_type      = this->subpixel_order_error
-	= this->active_error        = this->connector_name_error
-	= this->edid_error          = this->gamma_error
-	= this->width_mm_edid_error = this->height_mm_edid_error = error;
+	 = this->connector_type      = this->subpixel_order_error
+	 = this->active_error        = this->connector_name_error
+	 = this->edid_error          = this->gamma_error
+	 = this->width_mm_edid_error = this->height_mm_edid_error = error;
       goto cont;
     }
   if ((fields & (CRTC_INFO_WIDTH_MM | CRTC_INFO_HEIGHT_MM | CRTC_INFO_SUBPIXEL_ORDER | CRTC_INFO_CONNECTOR_TYPE)))
@@ -672,10 +673,12 @@ int libgamma_linux_drm_get_crtc_information(libgamma_crtc_information_t* restric
     goto cont;
   e |= get_edid(crtc, this, connector);
   if (this->edid == NULL)
-    goto cont;
-  e |= this->width_mm_edid_error = _E(CRTC_INFO_WIDTH_MM_EDID); /* TODO */
-  e |= this->height_mm_edid_error = _E(CRTC_INFO_HEIGHT_MM_EDID); /* TODO */
-  e |= this->gamma_error = _E(CRTC_INFO_GAMMA); /* TODO */
+    {
+      this->gamma_error = this->width_mm_edid_error = this->height_mm_edid_error = this->edid_error;
+      goto cont;
+    }
+  if ((fields & (CRTC_INFO_WIDTH_MM_EDID | CRTC_INFO_HEIGHT_MM_EDID | CRTC_INFO_GAMMA)))
+    e |= libgamma_parse_edid(this, fields);
  cont:
   e |= (fields & CRTC_INFO_GAMMA_SIZE) ? get_gamma_ramp_size(this, crtc) : 0;
   this->gamma_depth = 16;
diff --git a/src/gamma-x-randr.c b/src/gamma-x-randr.c
index 99a5a21..1d7b4bd 100644
--- a/src/gamma-x-randr.c
+++ b/src/gamma-x-randr.c
@@ -22,6 +22,7 @@
 #include "gamma-x-randr.h"
 
 #include "libgamma-error.h"
+#include "edid.h"
 
 #include <stdlib.h>
 #include <errno.h>
diff --git a/src/libgamma-error.h b/src/libgamma-error.h
index ba8ec86..c4da13c 100644
--- a/src/libgamma-error.h
+++ b/src/libgamma-error.h
@@ -179,6 +179,39 @@ extern const char* libgamma_group_name;
  */
 #define LIBGAMMA_SUBPIXEL_ORDER_NOT_RECOGNISED  (-27)
 
+/**
+ * The length of the EDID does not match that of any supported EDID structure revision
+ */
+#define LIBGAMMA_EDID_LENGTH_UNSUPPORTED  (-28)
+
+/**
+ * The magic number in the EDID does not match that of any supported EDID structure revision
+ */
+#define LIBGAMMA_EDID_WRONG_MAGIC_NUMBER  (-29)
+
+/**
+ * The EDID structure revision used by the monitor is not supported
+ */
+#define LIBGAMMA_EDID_REVISION_UNSUPPORTED  (-30)
+
+/**
+ * The gamma characteristics field in the EDID is left unspecified
+ * (This could be considered a non-error)
+ */
+#define LIBGAMMA_GAMMA_NOT_SPECIFIED  (-31)
+
+/**
+ * The checksum in the EDID is incorrect, all request information has been provided
+ * by you cannot count on it.
+ */
+#define LIBGAMMA_EDID_CHECKSUM_ERROR  (-32)
+
+/**
+ * Both of the errors `LIBGAMMA_GAMMA_NOT_SPECIFIED` and
+ * `LIBGAMMA_EDID_CHECKSUM_ERROR` have occurred
+ */
+#define LIBGAMMA_GAMMA_NOT_SPECIFIED_AND_EDID_CHECKSUM_ERROR  (-33)
+
 
 
 #endif