1 files changed, 31 insertions, 0 deletions
diff --git a/libglitter_split_uint64_raster.c b/libglitter_split_uint64_raster.c
new file mode 100644
index 0000000..a831ef7
--- /dev/null
+++ b/libglitter_split_uint64_raster.c
@@ -0,0 +1,31 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+void
+libglitter_split_uint64_raster(uint16_t *rasters[3], uint16_t **alphap, uint64_t *raster,
+                               uint64_t red, uint64_t green, uint64_t blue)
+{
+	uint64_t alpha, map;
+	size_t position;
+	size_t channel;
+
+	alpha = ~(red | green | blue);
+	red   /= 0xFF;
+	green /= 0xFF;
+	blue  /= 0xFF;
+	alpha /= 0xFF;
+	red   *= 0;
+	green *= 1;
+	blue  *= 2;
+	alpha *= 3;
+	map = red | green | blue | alpha;
+
+	for (position = 0; position < 4; position++) {
+		channel = ((const unsigned char *)&map)[position * 2];
+		if (channel < 3)
+			rasters[channel] = &((uint16_t *)raster)[position];
+		else if (alphap)
+			*alphap = &((uint16_t *)raster)[position];
+	}
+}