m + m fixes + doc

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

4 files changed, 123 insertions, 60 deletions

diff --git a/src/lib/gamma-helper.c b/src/lib/gamma-helper.c
index 11dfa13..e5f5a25 100644
--- a/src/lib/gamma-helper.c
+++ b/src/lib/gamma-helper.c
@@ -106,8 +106,8 @@ static void translate_from_64(signed depth, size_t n, libgamma_gamma_ramps_any_t
 static int allocated_any_ramp(libgamma_gamma_ramps_any_t* restrict ramps_sys,
 			      libgamma_gamma_ramps_any_t ramps, signed depth, size_t* restrict elements)
 {
+  /* Calculate the size of the allocation to do. */
   size_t d, n = ramps.ANY.red_size + ramps.ANY.green_size + ramps.ANY.blue_size;
-  
   switch (depth)
     {
     case 16:  d = sizeof(uint16_t);  break;
@@ -119,12 +119,16 @@ static int allocated_any_ramp(libgamma_gamma_ramps_any_t* restrict ramps_sys,
       return errno = EINVAL, LIBGAMMA_ERRNO_SET;
     }
   
+  /* Copy the gamma ramp sizes. */
   ramps_sys->ANY = ramps.ANY;
+  /* Allocate the new ramps. */
   ramps_sys->ANY.red   = malloc(n * d);
   ramps_sys->ANY.green = (void*)(((char*)(ramps_sys->ANY.  red)) + ramps.ANY.  red_size * d / sizeof(char));
   ramps_sys->ANY.blue  = (void*)(((char*)(ramps_sys->ANY.green)) + ramps.ANY.green_size * d / sizeof(char));
   
+  /* Report the total gamma ramp size. */
   *elements = n;
+  /* Report successfulness. */
   return ramps_sys->ANY.red == NULL ? LIBGAMMA_ERRNO_SET : 0;
 }
 
@@ -154,18 +158,23 @@ int libgamma_translated_ramp_get_(libgamma_crtc_state_t* restrict this,
   libgamma_gamma_ramps_any_t ramps_sys;
   uint64_t* restrict ramps_full;
   
+  /* Allocate ramps with proper data type. */
   if ((r = allocated_any_ramp(&ramps_sys, *ramps, depth_system, &n)))
     return r;
   
+  /* Fill the ramps. */
   if ((r = fun(this, &ramps_sys)))
     return free(ramps_sys.ANY.red), r;
   
+  /* Allocate intermediary ramps. */
   if ((ramps_full = malloc(n * sizeof(uint64_t))) == NULL)
     return free(ramps_sys.ANY.red), LIBGAMMA_ERRNO_SET;
   
+  /* Translate ramps to 64-bit integers. */
   translate_to_64(depth_system, n, ramps_full, ramps_sys);
   free(ramps_sys.ANY.red);
   
+  /* Translate ramps to the user's format. */
   translate_from_64(depth_user, n, *ramps, ramps_full);
   free(ramps_full);
   return 0;
@@ -197,16 +206,21 @@ int libgamma_translated_ramp_set_(libgamma_crtc_state_t* restrict this,
   libgamma_gamma_ramps_any_t ramps_sys;
   uint64_t* restrict ramps_full;
   
+  /* Allocate ramps with proper data type. */
   if ((r = allocated_any_ramp(&ramps_sys, ramps, depth_system, &n)))
     return r;
   
+  /* Allocate intermediary ramps. */
   if ((ramps_full = malloc(n * sizeof(uint64_t))) == NULL)
     return free(ramps_sys.ANY.red), LIBGAMMA_ERRNO_SET;
   
+  /* Translate ramps to 64-bit integers. */
   translate_to_64(depth_user, n, ramps_full, ramps);
+  /* Translate ramps to the proper format. */
   translate_from_64(depth_system, n, ramps_sys, ramps_full);
   free(ramps_full);
   
+  /* Apply the ramps */
   r = fun(this, ramps_sys);
   
   free(ramps_sys.ANY.red);
diff --git a/src/lib/gamma-quartz-cg.c b/src/lib/gamma-quartz-cg.c
index 3832ca5..b623303 100644
--- a/src/lib/gamma-quartz-cg.c
+++ b/src/lib/gamma-quartz-cg.c
@@ -41,20 +41,30 @@
  */
 void libgamma_quartz_cg_method_capabilities(libgamma_method_capabilities_t* restrict this)
 {
+  /* Gamma ramps size and depth can be queried. */
   this->crtc_information = LIBGAMMA_CRTC_INFO_GAMMA_SIZE
 			 | LIBGAMMA_CRTC_INFO_GAMMA_DEPTH;
+  /* Quartz/CoreGraphics does not support sites or partitions. */
   this->default_site_known = 1;
   this->multiple_sites = 0;
   this->multiple_partitions = 0;
+  /* Quartz/CoreGraphics does support CRTC:s. */
   this->multiple_crtcs = 1;
+  /* Partitions are not support... */
   this->partitions_are_graphics_cards = 0;
+  /* CoreGraphics have support for system restore. */
   this->site_restore = 1;
   this->partition_restore = 1;
+  /* But not for individual CRTC:s. */
   this->crtc_restore = 0;
+  /* Gamma ramp sizes are identifical but not fixed. */
   this->identical_gamma_sizes = 1;
   this->fixed_gamma_size = 0;
+  /* Gamma ramp depths are fixed. */
   this->fixed_gamma_depth = 1;
+  /* Quartz/CoreGraphics is a real adjustment method that can be faked. */
 #ifdef FAKE_LIBGAMMA_METHOD_QUARTZ_CORE_GRAPHICS
+  /* It is considered real but fake if it is translated to X RandR. */
   this->fake = 1;
 # ifdef HAVE_LIBGAMMA_METHOD_X_RANDR
   this->real = 1;
@@ -62,6 +72,7 @@ void libgamma_quartz_cg_method_capabilities(libgamma_method_capabilities_t* rest
   this->real = 0;
 # endif
 #else
+  /* It is real and not fake if we are running on Mac OS X. */
   this->fake = 0;
   this->real = 1;
 #endif
@@ -84,11 +95,8 @@ void libgamma_quartz_cg_method_capabilities(libgamma_method_capabilities_t* rest
 int libgamma_quartz_cg_site_initialise(libgamma_site_state_t* restrict this,
 				       char* restrict site)
 {
-  if (site != NULL)
-    return LIBGAMMA_NO_SUCH_SITE;
-  
   this->partitions_available = 1;
-  return 0;
+  return site != NULL ? LIBGAMMA_NO_SUCH_SITE : 0;
 }
 
 
@@ -135,7 +143,6 @@ int libgamma_quartz_cg_partition_initialise(libgamma_partition_state_t* restrict
   uint32_t cap = 4, n;
   CGDirectDisplayID* crtcs;
   CGDirectDisplayID* crtcs_old;
-  CGError r;
   
   (void) site;
   
@@ -144,34 +151,31 @@ int libgamma_quartz_cg_partition_initialise(libgamma_partition_state_t* restrict
   if (partition != 0)
     return LIBGAMMA_NO_SUCH_PARTITION;
   
-  crtcs = malloc((size_t)cap * sizeof(CGDirectDisplayID));
-  if (crtcs == NULL)
+  /* Allocate array of CRTC ID:s. */
+  if ((crtcs = malloc((size_t)cap * sizeof(CGDirectDisplayID))) == NULL)
     return LIBGAMMA_ERRNO_SET;
   
+  /* It is not possible to ask CoreGraphics how many CRTC:s
+     are available. We have to ask it to give us a ID:s of
+     a number of CRTC:s and ask for more if we got as many
+     as we asked for. */
   for (;;)
     {
-      r = CGGetOnlineDisplayList(cap, crtcs, &n);
-      if (r != kCGErrorSuccess)
-	{
-	  free(crtcs);
-	  return LIBGAMMA_LIST_CRTCS_FAILED;
-	}
+      /* Ask for CRTC ID:s */
+      if (CGGetOnlineDisplayList(cap, crtcs, &n) != kCGErrorSuccess)
+	return free(crtcs), LIBGAMMA_LIST_CRTCS_FAILED;
+      /* If we did not get as many as we asked for then we have all. */
       if (n < cap)
 	break;
-      if (cap == 0) /* We could also test ~0, but it is still too many. */
-	{
-	  free(crtcs);
-	  return LIBGAMMA_IMPOSSIBLE_AMOUNT;
-	}
-      crtcs_old = crtcs;
-      crtcs = realloc(crtcs, (size_t)cap * sizeof(CGDirectDisplayID));
-      if (crtcs)
-	{
-	  free(crtcs_old);
-	  return LIBGAMMA_ERRNO_SET;
-	}
+      /* Increase the number CRTC ID:s to ask for. */
+      if ((cap <<= 1) == 0) /* We could also test ~0, but it is still too many. */
+	return free(crtcs), LIBGAMMA_IMPOSSIBLE_AMOUNT;
+      /* Grow the array of CRTC ID:s so that it can fit all we are asking for. */
+      if ((crtcs = realloc(crtcs_old = crtcs, (size_t)cap * sizeof(CGDirectDisplayID))) == NULL)
+	return free(crtcs_old), LIBGAMMA_ERRNO_SET;
     }
   
+  /* Store CRTC ID:s and CRTC count. */
   this->data = crtcs;
   this->crtcs_available = (size_t)n;
   return 0;
@@ -216,9 +220,7 @@ int libgamma_quartz_cg_crtc_initialise(libgamma_crtc_state_t* restrict this,
 				       libgamma_partition_state_t* restrict partition, size_t crtc)
 {
   (void) this;
-  if (crtc >= partition->crtcs_available)
-    return LIBGAMMA_NO_SUCH_CRTC;
-  return 0;
+  return crtc >= partition->crtcs_available ? LIBGAMMA_NO_SUCH_CRTC : 0;
 }
 
 
@@ -260,39 +262,40 @@ int libgamma_quartz_cg_get_crtc_information(libgamma_crtc_information_t* restric
 					    libgamma_crtc_state_t* restrict crtc, int32_t fields)
 {
 #define SUPPORTED_FIELDS  (LIBGAMMA_CRTC_INFO_GAMMA_SIZE | LIBGAMMA_CRTC_INFO_GAMMA_DEPTH)
-   
 #define _E(FIELD)  ((fields & FIELD) ? LIBGAMMA_CRTC_INFO_NOT_SUPPORTED : 0)
   
+  /* Quartz/CoreGraphics does not support EDID or monitor dimensions. */
   this->edid_error = _E(LIBGAMMA_CRTC_INFO_EDID);
   this->width_mm_error = _E(LIBGAMMA_CRTC_INFO_WIDTH_MM);
   this->height_mm_error = _E(LIBGAMMA_CRTC_INFO_HEIGHT_MM);
   this->width_mm_edid_error = _E(LIBGAMMA_CRTC_INFO_WIDTH_MM_EDID);
   this->height_mm_edid_error = _E(LIBGAMMA_CRTC_INFO_HEIGHT_MM_EDID);
+  /* Quartz/CoreGraphics does support gamma ramp size query.
+     The gamma ramps are identical but not fixed, and the query can fail. */
+  this->gamma_size_error = 0;
   if ((fields & LIBGAMMA_CRTC_INFO_GAMMA_SIZE))
     {
-      CGDirectDisplayID* crtcs = crtc->partition->data;
-      CGDirectDisplayID crtc_id = crtcs[crtc->crtc];
-      size_t gamma_size = CGDisplayGammaTableCapacity(crtc_id);;
-      this->red_gamma_size = (size_t)gamma_size;
-      this->green_gamma_size = this->red_gamma_size;
-      this->blue_gamma_size = this->red_gamma_size;
+      CGDirectDisplayID* restrict crtcs = crtc->partition->data;
+      size_t gamma_size = CGDisplayGammaTableCapacity(crtcs[crtc->crtc]);
+      this->red_gamma_size = this->green_gamma_size = this->blue_gamma_size = (size_t)gamma_size;
       this->gamma_size_error = gamma_size < 2 ? LIBGAMMA_SINGLETON_GAMMA_RAMP : 0;
     }
-  else
-    this->gamma_size_error = 0;
+  /* Quartz/CoreGraphics uses `float` ramps. */
   this->gamma_depth = -1;
   this->gamma_depth_error = 0;
+  /* Quartz/CoreGraphics does not support gamma ramp support queries. */
   this->gamma_support_error = _E(LIBGAMMA_CRTC_INFO_GAMMA_SUPPORT);
+  /* Quartz/CoreGraphics does not support EDID or connector information. */
   this->subpixel_order_error = _E(LIBGAMMA_CRTC_INFO_SUBPIXEL_ORDER);
   this->active_error = _E(LIBGAMMA_CRTC_INFO_ACTIVE);
   this->connector_name_error = _E(LIBGAMMA_CRTC_INFO_CONNECTOR_NAME);
   this->connector_type_error = _E(LIBGAMMA_CRTC_INFO_CONNECTOR_TYPE);
   this->gamma_error = _E(LIBGAMMA_CRTC_INFO_GAMMA);
   
-#undef _E
-  
-  return this->gamma_size_error ? -1 : (fields & ~SUPPORTED_FIELDS) ? -1 : 0;
+  /* We failed if gamma ramp size query failed or if an unsupport field was queried. */
+  return this->gamma_size_error || (fields & ~SUPPORTED_FIELDS) ? -1 : 0;
   
+#undef _E
 #undef SUPPORTED_FIELDS
 }
 
@@ -313,14 +316,19 @@ int libgamma_quartz_cg_crtc_get_gamma_rampsf(libgamma_crtc_state_t* restrict thi
   uint32_t gamma_size_out;
   CGError r;
 #ifdef DEBUG
+  /* Gamma ramps sizes are identical but not fixed. */
   if ((ramps->red_size != ramps->green_size) ||
       (ramps->red_size != ramps->blue_size))
     return LIBGAMMA_MIXED_GAMMA_RAMP_SIZE;
 #endif
+  /* Read current gamma ramps. */
   r = CGGetDisplayTransferByTable(crtc_id, (uint32_t)(ramps->red_size),
 				  ramps->red, ramps->green, ramps->blue, &gamma_size_out);
   if (r != kCGErrorSuccess)
     return LIBGAMMA_GAMMA_RAMP_READ_FAILED;
+  /* I hope that it will not actually ever change,
+     but it does return the the gamma ramp size despite
+     that it can be queried without querying for more. */
   if (gamma_size_out != ramps->red_size)
     return LIBGAMMA_GAMMA_RAMP_SIZE_CHANGED;
   return 0;
@@ -342,10 +350,12 @@ int libgamma_quartz_cg_crtc_set_gamma_rampsf(libgamma_crtc_state_t* restrict thi
   CGDirectDisplayID crtc_id = crtcs[this->crtc];
   CGError r;
 #ifdef DEBUG
+  /* Gamma ramps sizes are identical but not fixed. */
   if ((ramps.red_size != ramps.green_size) ||
       (ramps.red_size != ramps.blue_size))
     return LIBGAMMA_MIXED_GAMMA_RAMP_SIZE;
 #endif
+  /* Apply gamma ramps. */
   r = CGSetDisplayTransferByTable(crtc_id, (uint32_t)(ramps.red_size),
 				  ramps.red, ramps.green, ramps.blue);
   return r == kCGErrorSuccess ? 0 : LIBGAMMA_GAMMA_RAMP_WRITE_FAILED;
diff --git a/src/lib/gamma-w32-gdi.c b/src/lib/gamma-w32-gdi.c
index f8c00ee..0cc6b07 100644
--- a/src/lib/gamma-w32-gdi.c
+++ b/src/lib/gamma-w32-gdi.c
@@ -35,6 +35,11 @@
 
 #include <errno.h>
 
+
+/**
+ * The gamma ramp size that devices will
+ * always have in Windows GDI.
+ */
 #define GAMMA_RAMP_SIZE  256
 
 
@@ -45,21 +50,29 @@
  */
 void libgamma_w32_gdi_method_capabilities(libgamma_method_capabilities_t* restrict this)
 {
+  /* Gamma ramps size, depth and support can be queried. */
   this->crtc_information = LIBGAMMA_CRTC_INFO_GAMMA_SIZE
 			 | LIBGAMMA_CRTC_INFO_GAMMA_DEPTH
 			 | LIBGAMMA_CRTC_INFO_GAMMA_SUPPORT;
+  /* Windows GDI does not support sites or partitions. */
   this->default_site_known = 1;
   this->multiple_sites = 0;
   this->multiple_partitions = 0;
+  /* Windows GDI does support CRTC:s. */
   this->multiple_crtcs = 1;
+  /* Partitions are not support... */
   this->partitions_are_graphics_cards = 0;
+  /* Windows GDI does not have system restore capabilities. */
   this->site_restore = 0;
   this->partition_restore = 0;
   this->crtc_restore = 0;
+  /* Ramps sizes are fixed and identical and ramp depth is too. */
   this->identical_gamma_sizes = 1;
   this->fixed_gamma_size = 1;
   this->fixed_gamma_depth = 1;
+  /* Windows GDI is a real adjustment method that can be faked. */
 #ifdef FAKE_LIBGAMMA_METHOD_W32_GDI
+  /* It is considered real but fake if it is translated to X RandR. */
   this->fake = 1;
 # ifdef HAVE_LIBGAMMA_METHOD_X_RANDR
   this->real = 1;
@@ -67,6 +80,7 @@ void libgamma_w32_gdi_method_capabilities(libgamma_method_capabilities_t* restri
   this->real = 0;
 # endif
 #else
+  /* It is real and not fake if we are running on Windows. */
   this->fake = 0;
   this->real = 1;
 #endif
@@ -89,11 +103,8 @@ void libgamma_w32_gdi_method_capabilities(libgamma_method_capabilities_t* restri
 int libgamma_w32_gdi_site_initialise(libgamma_site_state_t* restrict this,
 				     char* restrict site)
 {
-  if (site != NULL)
-    return LIBGAMMA_NO_SUCH_SITE;
-  
   this->partitions_available = 1;
-  return 0;
+  return site != NULL ? LIBGAMMA_NO_SUCH_SITE : 0;
 }
 
 
@@ -199,7 +210,8 @@ int libgamma_w32_gdi_crtc_initialise(libgamma_crtc_state_t* restrict this,
   
   this->data = NULL;
   
-  display.cb = sizeof(DISPLAY_DEVICE); /* Windows's API mandates this... */
+  /* Windows's API mandates this... */
+  display.cb = sizeof(DISPLAY_DEVICE);
   /* Get identifier for selected CRTC. */
   if (!EnumDisplayDevices(NULL, (DWORD)crtc, &display, 0))
     return LIBGAMMA_NO_SUCH_CRTC;
@@ -255,33 +267,38 @@ int libgamma_w32_gdi_get_crtc_information(libgamma_crtc_information_t* restrict
 					  libgamma_crtc_state_t* restrict crtc, int32_t fields)
 {
 #define KNOWN_FIELDS  (LIBGAMMA_CRTC_INFO_GAMMA_SIZE | LIBGAMMA_CRTC_INFO_GAMMA_DEPTH | LIBGAMMA_CRTC_INFO_GAMMA_SUPPORT)
-   
 #define _E(FIELD)  ((fields & FIELD) ? LIBGAMMA_CRTC_INFO_NOT_SUPPORTED : 0)
   
+  /* Windows GDI does not support EDID or monitor dimensions. */
   this->edid_error = _E(LIBGAMMA_CRTC_INFO_EDID);
   this->width_mm_error = _E(LIBGAMMA_CRTC_INFO_WIDTH_MM);
   this->height_mm_error = _E(LIBGAMMA_CRTC_INFO_HEIGHT_MM);
   this->width_mm_edid_error = _E(LIBGAMMA_CRTC_INFO_WIDTH_MM_EDID);
   this->height_mm_edid_error = _E(LIBGAMMA_CRTC_INFO_HEIGHT_MM_EDID);
+  /* Windows GDI have fixed gamma ramp sizes. */
   this->red_gamma_size = GAMMA_RAMP_SIZE;
   this->green_gamma_size = GAMMA_RAMP_SIZE;
   this->blue_gamma_size = GAMMA_RAMP_SIZE;
   this->gamma_size_error = 0;
+  /* Windows GDI have fixed gamma ramp depth. */
   this->gamma_depth = 16;
   this->gamma_depth_error = 0;
+  /* It is possible to query Windows GDI whether the device
+     have gamma ramp support. It cannot fail. */
   if ((fields & LIBGAMMA_CRTC_INFO_GAMMA_SUPPORT))
     this->gamma_support = GetDeviceCaps(crtc->data, COLORMGMTCAPS) == CM_GAMMA_RAMP;
   this->gamma_support_error = 0;
+  /* Windows GDI does not support EDID or connector information. */
   this->subpixel_order_error = _E(LIBGAMMA_CRTC_INFO_SUBPIXEL_ORDER);
   this->active_error = _E(LIBGAMMA_CRTC_INFO_ACTIVE);
   this->connector_name_error = _E(LIBGAMMA_CRTC_INFO_CONNECTOR_NAME);
   this->connector_type_error = _E(LIBGAMMA_CRTC_INFO_CONNECTOR_TYPE);
   this->gamma_error = _E(LIBGAMMA_CRTC_INFO_GAMMA);
   
-#undef _E
-  
+  /* There was a failure if and only if unsupport field was requested. */
   return (fields & ~KNOWN_FIELDS) ? -1 : 0;
   
+#undef _E
 #undef  KNOWN_FIELDS
 }
 
@@ -298,11 +315,13 @@ int libgamma_w32_gdi_crtc_get_gamma_ramps(libgamma_crtc_state_t* restrict this,
 					  libgamma_gamma_ramps_t* restrict ramps)
 {
 #ifdef DEBUG
+  /* Windows GDI have fixed gamma ramp sizes. */
   if ((ramps->  red_size != GAMMA_RAMP_SIZE) ||
       (ramps->green_size != GAMMA_RAMP_SIZE) ||
       (ramps-> blue_size != GAMMA_RAMP_SIZE))
     return LIBGAMMA_WRONG_GAMMA_RAMP_SIZE;
 #endif
+  /* Read current gamma ramps. */
   if (!GetDeviceGammaRamp(this->data, ramps->red))
     return LIBGAMMA_GAMMA_RAMP_READ_FAILED;
   return 0;
@@ -321,11 +340,13 @@ int libgamma_w32_gdi_crtc_set_gamma_ramps(libgamma_crtc_state_t* restrict this,
 					  libgamma_gamma_ramps_t ramps)
 {
 #ifdef DEBUG
+  /* Windows GDI have fixed gamma ramp sizes. */
   if ((ramps.  red_size != GAMMA_RAMP_SIZE) ||
       (ramps.green_size != GAMMA_RAMP_SIZE) ||
       (ramps. blue_size != GAMMA_RAMP_SIZE))
     return LIBGAMMA_WRONG_GAMMA_RAMP_SIZE;
 #endif
+  /* Apply gamma ramps. */
   if (!SetDeviceGammaRamp(this->data, ramps.red))
     return LIBGAMMA_GAMMA_RAMP_WRITE_FAILED;
   return 0;
diff --git a/src/lib/gamma-x-vidmode.c b/src/lib/gamma-x-vidmode.c
index a73f36f..170d3b4 100644
--- a/src/lib/gamma-x-vidmode.c
+++ b/src/lib/gamma-x-vidmode.c
@@ -38,19 +38,26 @@
 void libgamma_x_vidmode_method_capabilities(libgamma_method_capabilities_t* restrict this)
 {
   char* restrict display = getenv("DISPLAY");
+  /* Gamma ramps size anddepth can be queried. */
   this->crtc_information = LIBGAMMA_CRTC_INFO_GAMMA_SIZE
 			 | LIBGAMMA_CRTC_INFO_GAMMA_DEPTH;
+  /* X VidMode supports multiple sits and partitions but not CRTC:s. */
   this->default_site_known = (display && *display);
   this->multiple_sites = 1;
   this->multiple_partitions = 1;
-  this->multiple_crtcs = 1;
+  this->multiple_crtcs = 0;
+  /* Partitions are screens and not graphics cards in X. */
   this->partitions_are_graphics_cards = 0;
+  /* X does not have system restore capabilities. */
   this->site_restore = 0;
   this->partition_restore = 0;
   this->crtc_restore = 0;
+  /* Gamma ramp sizes are identical but not fixed. */
   this->identical_gamma_sizes = 1;
   this->fixed_gamma_size = 0;
+  /* Gamma ramp depths are fixed. */
   this->fixed_gamma_depth = 1;
+  /* X VidMode is a real non-faked adjustment method */
   this->real = 1;
   this->fake = 0;
 }
@@ -72,14 +79,17 @@ void libgamma_x_vidmode_method_capabilities(libgamma_method_capabilities_t* rest
 int libgamma_x_vidmode_site_initialise(libgamma_site_state_t* restrict this,
 				       char* restrict site)
 {
+  /* Connect to the display. */
   Display* restrict connection = XOpenDisplay(site);
   int _major, _minor, screens;
   if ((this->data = connection) == NULL)
     return LIBGAMMA_OPEN_SITE_FAILED;
+  /* Query X VidMode extension protocol version. */
   if (!XF86VidModeQueryVersion(connection, &_major, &_minor))
-    return LIBGAMMA_PROTOCOL_VERSION_QUERY_FAILED;
+    return XCloseDisplay(connection), LIBGAMMA_PROTOCOL_VERSION_QUERY_FAILED;
+  /* Query the number of available screens. */
   if ((screens = ScreenCount(connection)) < 0)
-    return LIBGAMMA_NEGATIVE_PARTITION_COUNT;
+    return XCloseDisplay(connection), LIBGAMMA_NEGATIVE_PARTITION_COUNT;
   this->partitions_available = (size_t)screens;
   return 0;
 }
@@ -123,10 +133,8 @@ int libgamma_x_vidmode_site_restore(libgamma_site_state_t* restrict this)
 int libgamma_x_vidmode_partition_initialise(libgamma_partition_state_t* restrict this,
 					    libgamma_site_state_t* restrict site, size_t partition)
 {
-  if (partition >= site->partitions_available)
-    return LIBGAMMA_NO_SUCH_PARTITION;
   this->crtcs_available = 1;
-  return 0;
+  return partition >= site->partitions_available ? LIBGAMMA_NO_SUCH_PARTITION : 0;
 }
 
 
@@ -213,35 +221,41 @@ int libgamma_x_vidmode_get_crtc_information(libgamma_crtc_information_t* restric
 {
 #define _E(FIELD)  ((fields & FIELD) ? LIBGAMMA_CRTC_INFO_NOT_SUPPORTED : 0)
   
+  /* X VidMode does not support EDID or monitor dimensions. */
   this->edid_error = _E(LIBGAMMA_CRTC_INFO_EDID);
   this->width_mm_error = _E(LIBGAMMA_CRTC_INFO_WIDTH_MM);
   this->height_mm_error = _E(LIBGAMMA_CRTC_INFO_HEIGHT_MM);
   this->width_mm_edid_error = _E(LIBGAMMA_CRTC_INFO_WIDTH_MM_EDID);
   this->height_mm_edid_error = _E(LIBGAMMA_CRTC_INFO_HEIGHT_MM_EDID);
   this->gamma_size_error = 0;
+  /* X VidMode does support gamma ramp size query. The gamma
+     ramps are identical but not fixed, and the query can fail. */
   if ((fields & LIBGAMMA_CRTC_INFO_GAMMA_SUPPORT))
     {
       Display* restrict connection = crtc->partition->site->data;
-      int stops;
+      int stops = 0;
       if (!XF86VidModeGetGammaRampSize(connection, (int)(crtc->partition->partition), &stops))
 	this->gamma_size_error = LIBGAMMA_GAMMA_RAMPS_SIZE_QUERY_FAILED;
       else if (stops < 2)
 	this->gamma_size_error = LIBGAMMA_SINGLETON_GAMMA_RAMP;
-      else
-	this->red_gamma_size = this->green_gamma_size = this->blue_gamma_size = (size_t)stops;
+      this->red_gamma_size = this->green_gamma_size = this->blue_gamma_size = (size_t)stops;
     }
+  /* X VidMode uses 16-bit integer ramps. */
   this->gamma_depth = 16;
   this->gamma_depth_error = 0;
+  /* X VidMode does not support gamma ramp support queries. */
   this->gamma_support_error = _E(LIBGAMMA_CRTC_INFO_GAMMA_SUPPORT);
+  /* X VidMode does not support EDID or connector information. */
   this->subpixel_order_error = _E(LIBGAMMA_CRTC_INFO_SUBPIXEL_ORDER);
   this->active_error = _E(LIBGAMMA_CRTC_INFO_ACTIVE);
   this->connector_name_error = _E(LIBGAMMA_CRTC_INFO_CONNECTOR_NAME);
   this->connector_type_error = _E(LIBGAMMA_CRTC_INFO_CONNECTOR_TYPE);
   this->gamma_error = _E(LIBGAMMA_CRTC_INFO_GAMMA);
   
-#undef _E
+  /* We failed if gamma ramp size query failed or if an unsupport field was queried. */
+  return this->gamma_size_error || (fields & ~(LIBGAMMA_CRTC_INFO_GAMMA_DEPTH | LIBGAMMA_CRTC_INFO_GAMMA_SIZE)) ? -1 : 0;
   
-  return (fields & ~(LIBGAMMA_CRTC_INFO_GAMMA_DEPTH | LIBGAMMA_CRTC_INFO_GAMMA_SIZE)) ? -1 : this->gamma_size_error;
+#undef _E
 }
 
 
@@ -257,10 +271,12 @@ int libgamma_x_vidmode_crtc_get_gamma_ramps(libgamma_crtc_state_t* restrict this
 					    libgamma_gamma_ramps_t* restrict ramps)
 {
 #ifdef DEBUG
+  /* Gamma ramp sizes are identical but not fixed. */
   if ((ramps->red_size != ramps->green_size) ||
       (ramps->red_size != ramps->blue_size))
     return LIBGAMMA_MIXED_GAMMA_RAMP_SIZE;
 #endif
+  /* Read current gamma ramps. */
   if (!XF86VidModeGetGammaRamp((Display*)(this->partition->site->data), (int)(this->partition->partition),
 			       (int)(ramps->red_size), ramps->red, ramps->green, ramps->blue))
     return LIBGAMMA_GAMMA_RAMP_READ_FAILED;
@@ -280,10 +296,12 @@ int libgamma_x_vidmode_crtc_set_gamma_ramps(libgamma_crtc_state_t* restrict this
 					    libgamma_gamma_ramps_t ramps)
 {
 #ifdef DEBUG
+  /* Gamma ramp sizes are identical but not fixed. */
   if ((ramps.red_size != ramps.green_size) ||
       (ramps.red_size != ramps.blue_size))
     return LIBGAMMA_MIXED_GAMMA_RAMP_SIZE;
 #endif
+  /* Apply gamma ramps. */
   if (!XF86VidModeSetGammaRamp((Display*)(this->partition->site->data), (int)(this->partition->partition),
 			       (int)(ramps.red_size), ramps.red, ramps.green, ramps.blue))
     return LIBGAMMA_GAMMA_RAMP_WRITE_FAILED;