1 files changed, 90 insertions, 0 deletions
diff --git a/src/stem/monitor.c b/src/stem/monitor.c
new file mode 100644
index 0000000..8c4744a
--- /dev/null
+++ b/src/stem/monitor.c
@@ -0,0 +1,90 @@
+#include "monitor.h"
+#include "sys.h"
+
+static int cursor_x = 0, cursor_y = 0;
+static uint16_t *video_memory = (uint16_t*)0xE00B8000;
+
+static void move_cursor() {
+	uint16_t cursor_location = cursor_y * 80 + cursor_x;
+	outb(0x3D4, 14);	//Sending high cursor byte
+	outb(0x3D5, cursor_location >> 8);
+	outb(0x3D4, 15);	//Sending high cursor byte
+	outb(0x3D5, cursor_location);
+}
+
+static void scroll() {
+	uint8_t attribute_byte = (0 /* black */ << 4) | (7/* white */ & 0x0F);
+	uint16_t blank = (attribute_byte << 8) | 0x20;
+
+	if (cursor_y >= 25) {
+		int i;
+		for (i = 0; i < 80*24; i++) {
+			video_memory[i] = video_memory[i+80];
+		}
+		for (i = 80*24; i < 80*25; i++) {
+			video_memory[i] = blank;
+		}
+		cursor_y = 24;
+	}
+}
+
+void monitor_put(char c) {
+	uint8_t fg = 7;	//White
+	uint8_t bg = 0; //Black
+
+	uint16_t attribute = (fg & 0x0F) | (bg << 4);
+	attribute = attribute << 8;
+
+	if (c == 0x08 && cursor_x) {	//Backspace
+		cursor_x--;
+	} else if (c == 0x09) {	//Tab
+		cursor_x = (cursor_x + 8) & ~(8 - 1);
+	} else if (c == '\r') {	//Carriage return
+		cursor_x = 0;
+	} else if (c == '\n') {	//New line
+		cursor_x = 0;
+		cursor_y++;
+	} else if (c >= ' ') {	//Any printable character
+		video_memory[cursor_y * 80 + cursor_x] = c | attribute;
+		cursor_x++;
+	}
+	if (cursor_x >= 80) {
+		cursor_x = 0;
+		cursor_y++;
+	}
+
+	scroll();
+	move_cursor();
+}
+
+void monitor_clear() {
+	uint8_t attribute_byte = (0 /* black */ << 4) | (15 /* white */ & 0x0F);
+	uint16_t blank = (attribute_byte << 8) | 0x20;
+
+	int i;
+
+	for (i = 0; i < 80*25; i++) {
+		video_memory[i] = blank;
+	}
+
+	cursor_x = 0; cursor_y = 0;
+	move_cursor();
+}
+
+void monitor_write(char *s) {
+	while (*s) {
+		monitor_put(*(s++));
+	}
+}
+
+void monitor_writeHex(uint32_t v) {
+	int i;
+
+	monitor_put('0'); monitor_put('x');
+	char hexdigits[] = "0123456789abcdef";
+
+	for (i = 0; i < 8; i++) {
+		monitor_put(hexdigits[v >> 28]);
+		v = v << 4;
+	}
+}