1 files changed, 78 insertions, 0 deletions
diff --git a/video.c b/video.c
new file mode 100644
index 0000000..ee53ea4
--- /dev/null
+++ b/video.c
@@ -0,0 +1,78 @@
+/* LCD controller driver for 680 project.
+ *
+ * Copyright 2010, Duncan Smith
+ * GPL
+ */
+
+#include <graph.h>
+#include <nostub.h>
+
+#define VIDEO_ROWMODE 0x01
+#define VIDEO_COLMODE 0x00
+char video_row;
+
+#define VIDEO_AUTOINC 0x02
+#define VIDEO_AUTODEC 0x00
+char video_increment;
+
+#define VIDEO_ENABLED 0x00
+#define VIDEO_DISABLED 0x20
+char video_enabled;
+
+#define VIDEO_6BIT 0x00
+#define VIDEO_8BIT 0x40
+char video_6bit;
+
+char video_busy;        // Always 0
+
+char video_cur_row;
+char video_cur_col;
+
+void video_write(char);
+char video_read(void);
+void *video_compute_address(void);
+int video_compute_shift(void);
+
+void video_write(char data)
+{
+	int shift = video_compute_shift();
+	short int data_mask = ~(0xff00 >> shift);
+	short int data_dat = data >> (shift-8);
+	void *addr = video_compute_address();
+	*((short int *)addr) &= data_mask;
+	*((short int *)addr) |= data_dat;
+	return;
+}
+
+char video_read(void)
+{
+	int shift = video_compute_shift();
+	void *addr = video_compute_address();
+	short int data = *((short int *)addr);
+	data <<= (shift-8);
+	data &= 0xff;
+	return;
+}
+
+void *video_compute_address()
+{
+	void *addr;
+	int off;
+
+	addr = LCD_MEM;
+	addr += (video_cur_row) * (240 / 8);
+
+	if (video_6bit == VIDEO_6BIT)
+		off = video_cur_col * 6 / 8;
+	else
+		off = video_cur_col;
+	return addr + off;
+}
+
+int video_compute_shift()
+{
+	if (video_6bit == VIDEO_8BIT)
+		return 0;
+
+	return (video_cur_col * 6) % 8;
+}