2 files changed, 92 insertions, 2 deletions

diff --git a/src/drmgamma.c b/src/drmgamma.c
index 16a3006..e0dcbfb 100644
--- a/src/drmgamma.c
+++ b/src/drmgamma.c
@@ -162,9 +162,14 @@ int drm_crtc_open(size_t index, drm_card_t* restrict card, drm_crtc_t* restrict
 {
   drmModePropertyRes* restrict prop;
   drmModePropertyBlobRes* restrict blob;
+  drmModeCrtc* restrict info;
   size_t i;
+  int old_errno;
   
-  crtc->edid = NULL;
+  crtc->edid  = NULL;
+  crtc->red   = NULL;
+  crtc->green = NULL;
+  crtc->blue  = NULL;
   
   crtc->id = card->res->crtcs[index];
   crtc->card = card;
@@ -179,6 +184,19 @@ int drm_crtc_open(size_t index, drm_card_t* restrict card, drm_crtc_t* restrict
   
   crtc->connected = crtc->connector->connection == DRM_MODE_CONNECTED;
   
+  info = drmModeGetCrtc(card->fd, crtc->id);
+  if (info == NULL)
+    return -1;
+  crtc->gamma_stops = (size_t)(info->gamma_size);
+  drmModeFreeCrtc(info);
+  
+  /* `calloc` is for some reason required when reading the gamma ramps. */
+  crtc->red = calloc(3 * crtc->gamma_stops, sizeof(uint16_t));
+  if (crtc->red == NULL)
+    return -1;
+  crtc->green = crtc->red   + crtc->gamma_stops;
+  crtc->blue  = crtc->green + crtc->gamma_stops;
+  
   for (i = 0; i < crtc->connector->count_props; i++)
     {
       size_t j;
@@ -199,8 +217,11 @@ int drm_crtc_open(size_t index, drm_card_t* restrict card, drm_crtc_t* restrict
       crtc->edid = malloc((blob->length * 2 + 1) * sizeof(char));
       if (crtc->edid == NULL)
 	{
+	  old_errno = errno;
 	  drmModeFreePropertyBlob(blob);
 	  drmModeFreeProperty(prop);
+	  free(crtc->red), crtc->red = NULL;
+	  errno = old_errno;
 	  return -1;
 	}
       for (j = 0; j < blob->length; j++)
@@ -231,5 +252,36 @@ int drm_crtc_open(size_t index, drm_card_t* restrict card, drm_crtc_t* restrict
 void drm_crtc_close(drm_crtc_t* restrict crtc)
 {
   free(crtc->edid), crtc->edid = NULL;
+  free(crtc->red), crtc->red = NULL;
+}
+
+
+/**
+ * Read the gamma ramps for a CRT controller
+ * 
+ * @param   crtc  CRT controller information
+ * @return        Zero on success, -1 on error 
+ */
+int drm_get_gamma(drm_crtc_t* restrict crtc)
+{
+  int r;
+  r = drmModeCrtcGetGamma(crtc->card->fd, crtc->id, crtc->gamma_stops,
+			  crtc->red, crtc->green, crtc->blue);
+  return -!!r;
+}
+
+
+/**
+ * Apply gamma ramps for a CRT controller
+ * 
+ * @param   crtc  CRT controller information
+ * @return        Zero on success, -1 on error
+ */
+int drm_set_gamma(drm_crtc_t* restrict crtc)
+{
+  int r;
+  r = drmModeCrtcSetGamma(crtc->card->fd, crtc->id, crtc->gamma_stops,
+			  crtc->red, crtc->green, crtc->blue);
+  return -!!r;
 }
 
diff --git a/src/drmgamma.h b/src/drmgamma.h
index efc7ec2..e82159d 100644
--- a/src/drmgamma.h
+++ b/src/drmgamma.h
@@ -61,6 +61,7 @@ typedef struct drm_card
   
 } drm_card_t;
 
+
 /**
  * CRT controller information
  */
@@ -94,11 +95,32 @@ typedef struct drm_crtc
   /**
    * The CRT's EDID, hexadecimally encoded
    */
-  char* edid;
+  char* restrict edid;
+  
+  /**
+   * The number of stops on the gamma ramps
+   */
+  size_t gamma_stops;
+  
+  /**
+   * The gamma ramp for the red channel
+   */
+  uint16_t* restrict red;
+  
+  /**
+   * The gamma ramp for the green channel
+   */
+  uint16_t* restrict green;
+  
+  /**
+   * The gamma ramp for the blue channel
+   */
+  uint16_t* restrict blue;
   
 } drm_crtc_t;
 
 
+
 /**
  * Figure out how many graphics cards there are on the system
  * 
@@ -139,6 +161,22 @@ int drm_crtc_open(size_t index, drm_card_t* restrict card, drm_crtc_t* restrict
  */
 void drm_crtc_close(drm_crtc_t* restrict crtc);
 
+/**
+ * Read the gamma ramps for a CRT controller
+ * 
+ * @param   crtc  CRT controller information
+ * @return        Zero on success, -1 on error 
+ */
+int drm_get_gamma(drm_crtc_t* restrict crtc);
+
+/**
+ * Apply gamma ramps for a CRT controller
+ * 
+ * @param   crtc  CRT controller information
+ * @return        Zero on success, -1 on error
+ */
+int drm_set_gamma(drm_crtc_t* restrict crtc);
+
 
 #endif