1 files changed, 69 insertions, 0 deletions
diff --git a/src/core/stencil.c b/src/core/stencil.c
new file mode 100644
index 0000000..3127544
--- /dev/null
+++ b/src/core/stencil.c
@@ -0,0 +1,69 @@
+#include "stencil.h"
+#include "mem.h"
+#include "../util/assert.h"
+
+bool stencil_always(byte src, byte ref) {
+	return 1;
+}
+
+bool stencil_never(byte src, byte ref) {
+	return 0;
+}
+
+bool stencil_less(byte src, byte ref) {
+	return src < ref;
+}
+
+bool stencil_equal(byte src, byte ref) {
+	return src == ref;
+}
+
+bool stencil_leuqal(byte src, byte ref) {
+	return src <= ref;
+}
+
+bool stencil_greater(byte src, byte ref) {
+	return src > ref;
+}
+
+bool stencil_notequal(byte src, byte ref) {
+	return src != ref;
+}
+
+bool stencil_gequer(byte src, byte ref) {
+	return src >= ref;
+}
+
+/*stencil op*/
+
+byte stencilop_keep(byte src, byte ref) {
+	return src;
+}
+
+byte stencilop_zero(byte src, byte ref) {
+	return 0;
+}
+
+byte stencilop_replace(byte src, byte ref) {
+	return ref;
+}
+
+byte stencilop_incr(byte src, byte ref) {
+	return src == 0xff ? 0xff : src + 1;
+}
+
+byte stencilop_incrwrap(byte src, byte ref) {
+	return src == 0xff ? 0 : src + 1;
+}
+
+byte stencilop_decr(byte src, byte ref) {
+	return src == 0 ? 0 : src - 1;
+}
+
+byte stencilop_decrwrap(byte src, byte ref) {
+	return src == 0 ? 0xff : src - 1;
+}
+
+byte stencilop_invert(byte src, byte ref) {
+	return (~src) & 0xff;
+}