Add libglitter_split_uint{64,32}_raster

Signed-off-by: Mattias Andrée <maandree@kth.se>

4 files changed, 72 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index 4731a2f..7db2755 100644
--- a/Makefile
+++ b/Makefile
@@ -29,6 +29,8 @@ OBJ =\
 	libglitter_free_render_context.o\
 	libglitter_get_colour_space_conversion_matrix_double.o\
 	libglitter_get_colour_space_conversion_matrix_float.o\
+	libglitter_split_uint32_raster.o\
+	libglitter_split_uint64_raster.o\
 	libglitter_update_render_context.o
 
 HDR =\
@@ -47,6 +49,7 @@ libglitter_compose_uint32.o: libglitter_compose_uint64.c libglitter_compose_doub
 libglitter_compose_uint64.o: libglitter_compose_double.c
 libglitter_compose_uint8.o: libglitter_compose_uint64.c libglitter_compose_double.c
 libglitter_desaturate_float.o: libglitter_desaturate_double.c
+libglitter_split_uint32_raster.o: libglitter_split_uint64_raster.c
 
 .c.o:
 	$(CC) -c -o $@ $< $(CFLAGS) $(CPPFLAGS)
diff --git a/libglitter.h b/libglitter.h
index 826ca16..dfb9e30 100644
--- a/libglitter.h
+++ b/libglitter.h
@@ -158,6 +158,39 @@ void libglitter_compose_uint8(uint8_t **, const uint8_t *restrict, size_t, size_
 
 
 /**
+ * Splits a `uint64_t` raster into one `uint16_t` raster per channel
+ * 
+ * @param  rasters   Output array for the rasters, they will be in the
+ *                   order (0) red, (1) green, (2) blue
+ * @param  alphap    Output parameter for the alpha mask rasters, or `NULL`
+ * @param  raster    The raster that is being split
+ * @param  red       The value `0xFFFF` shifted such that value
+ *                   expresses pure red (closest primary colour)
+ * @param  green     The value `0xFFFF` shifted such that value
+ *                   expresses pure green (closest primary colour)
+ * @param  blue      The value `0xFFFF` shifted such that value
+ *                   expresses pure blue (closest primary colour)
+ */
+void libglitter_split_uint64_raster(uint16_t *[3], uint16_t **, uint64_t *, uint64_t, uint64_t, uint64_t);
+
+/**
+ * Splits a `uint32_t` raster into one `uint8_t` raster per channel
+ * 
+ * @param  rasters   Output array for the rasters, they will be in the
+ *                   order (0) red, (1) green, (2) blue
+ * @param  alphap    Output parameter for the alpha mask rasters, or `NULL`
+ * @param  raster    The raster that is being split
+ * @param  red       The value `0xFF` shifted such that value
+ *                   expresses pure red (closest primary colour)
+ * @param  green     The value `0xFF` shifted such that value
+ *                   expresses pure green (closest primary colour)
+ * @param  blue      The value `0xFF` shifted such that value
+ *                   expresses pure blue (closest primary colour)
+ */
+void libglitter_split_uint32_raster(uint8_t *[3], uint8_t **, uint32_t *, uint32_t, uint32_t, uint32_t);
+
+
+/**
  * Transform rasters from fully using subpixel rendering to
  * balance between subpixel rendering and greyscale antialiasing
  * 
diff --git a/libglitter_split_uint32_raster.c b/libglitter_split_uint32_raster.c
new file mode 100644
index 0000000..a8b44f5
--- /dev/null
+++ b/libglitter_split_uint32_raster.c
@@ -0,0 +1,5 @@
+#include "common.h"
+#define libglitter_split_uint64_raster libglitter_split_uint32_raster
+#define uint64_t uint32_t
+#define uint16_t uint8_t
+#include "libglitter_split_uint64_raster.c"
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];
+	}
+}