1 files changed, 43 insertions, 0 deletions
diff --git a/esp32/main/scrn.c b/esp32/main/scrn.c
new file mode 100644
index 0000000..d455e5b
--- /dev/null
+++ b/esp32/main/scrn.c
@@ -0,0 +1,43 @@
+#include <esp_log.h>
+
+#include "scrn.h"
+
+#define MASK_ON(x) (1ULL << (7 - (x % 8)))
+#define MASK_OFF(x) ~(1ULL << (7 - (x % 8)))
+
+const static char *TAG = "scrn";
+
+void scrn_clear(struct scrn *sc)
+{
+	int n = sc->width * sc->height / 8;
+
+	for (int i = 0; i < n; i++)
+		sc->fb[i] = 0;
+}
+
+void scrn_draw(struct scrn *sc, struct sprite *s)
+{
+	int s_n = s->width * s->height;
+	int buf_n = sc->width * sc->height;
+	int buf_i = s->offset_y * sc->width + s->offset_x;
+
+	int s_i = 0, s_col = 0;
+
+	while (s_i < s_n) {
+		if (s_col == s->width) {
+			s_col = 0;
+			buf_i += sc->width - s->width;
+		}
+
+		if (s->bmp[s_i / 8] & MASK_ON(s_i)) {
+			if (buf_i < buf_n)
+				sc->fb[buf_i / 8] |= MASK_ON(buf_i);
+			else
+				ESP_LOGE(TAG, "draw(): pixel out of range");
+		}
+
+		s_i++;
+		buf_i++;
+		s_col++;
+	}
+}