1 files changed, 59 insertions, 0 deletions
diff --git a/libgamma_quartz_cg_partition_initialise.c b/libgamma_quartz_cg_partition_initialise.c
new file mode 100644
index 0000000..694ecbc
--- /dev/null
+++ b/libgamma_quartz_cg_partition_initialise.c
@@ -0,0 +1,59 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+/**
+ * Initialise an allocated partition state
+ * 
+ * @param   this       The partition state to initialise
+ * @param   site       The site state for the site that the partition belongs to
+ * @param   partition  The the index of the partition within the site
+ * @return             Zero on success, otherwise (negative) the value of an
+ *                     error identifier provided by this library
+ */
+int
+libgamma_quartz_cg_partition_initialise(libgamma_partition_state_t *restrict this,
+                                       libgamma_site_state_t *restrict site, size_t partition)
+{
+	CGDirectDisplayID *crtcs, *crtcs_old;
+	uint32_t cap = 4, n;
+
+	(void) site;
+
+	this->data = NULL;
+
+	if (partition)
+		return LIBGAMMA_NO_SUCH_PARTITION;
+
+	/* Allocate array of CRTC ID:s */
+	crtcs = malloc((size_t)cap * sizeof(CGDirectDisplayID));
+	if (!crtcs)
+		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 (;;) {
+		/* 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;
+		/* Increase the number CRTC ID:s to ask for */
+		if (cap > SIZE_MAX / 2) /* We could also test ~0, but it is still too many */
+			return free(crtcs), LIBGAMMA_IMPOSSIBLE_AMOUNT;
+		cap <<= 1;
+		/* Grow the array of CRTC ID:s so that it can fit all we are asking for */
+		crtcs = realloc(crtcs_old = crtcs, (size_t)cap * sizeof(CGDirectDisplayID));
+		if (!crtcs) {
+			free(crtcs_old);
+			return LIBGAMMA_ERRNO_SET;
+		}
+	}
+
+	/* Store CRTC ID:s and CRTC count */
+	this->data = crtcs;
+	this->crtcs_available = (size_t)n;
+	return 0;
+}