first real commit

3 files changed, 121 insertions, 0 deletions

diff --git a/drivers/tty.c b/drivers/tty.c
new file mode 100644
index 0000000..e938abd
--- /dev/null
+++ b/drivers/tty.c
@@ -0,0 +1,86 @@
+#include <stdint.h>
+#include "io.h"
+#include "tty.h"
+#include "vga.h"
+
+static int term_x, term_y;
+static uint8_t term_col;
+/* VGA buffer starts at 0xB8000 */
+static uint16_t *term_buf;
+
+void tty_init(void)
+{
+    term_buf = (uint16_t*)0xB8000;
+    term_col = VGA_MAKE_COLOR(VGA_WHITE, VGA_BLACK);
+    tty_clear();
+}
+
+static void move_cursor(uint16_t cursor_idx)
+{
+    outb(0x3D4, 14);
+    outb(0x3D5, cursor_idx >> 8); // high byte
+    outb(0x3D4, 15);
+    outb(0x3D5, cursor_idx); // low byte
+}
+
+static void update_cursor(void)
+{
+    move_cursor(term_y * VGA_WIDTH + term_x);
+}
+
+void tty_clear(void)
+{
+    term_x = 0;
+    term_y = 0;
+    for(int y = 0; y < VGA_HEIGHT; ++y)
+    {
+        for(int x = 0; x < VGA_WIDTH; ++x)
+        {
+            term_buf[y * VGA_WIDTH + x] = VGA_MAKE_ENTRY(' ', term_col);
+        }
+    }
+}
+
+void tty_set_color(uint8_t color)
+{
+    term_col = color;
+}
+
+uint8_t tty_get_color(void)
+{
+    return term_col;
+}
+
+void tty_putchar_at(char ch, uint8_t col, int x, int y)
+{
+    term_buf[y * VGA_WIDTH + x] = VGA_MAKE_ENTRY(ch, col);
+}
+
+void tty_putchar(char ch)
+{
+    if(ch != '\n')
+    {
+        tty_putchar_at(ch, term_col, term_x, term_y);
+        if(++term_x == VGA_WIDTH)
+        {
+            term_x = 0;
+            if(++term_y == VGA_HEIGHT)
+                term_y = 0;
+        }
+    }
+    else
+    {
+        term_x = 0;
+        if(++term_y == VGA_HEIGHT)
+            term_y = 0;
+    }
+    update_cursor();
+}
+
+void tty_puts(const char *str)
+{
+    while(*str)
+    {
+        tty_putchar(*str++);
+    }
+}
diff --git a/drivers/tty.h b/drivers/tty.h
new file mode 100644
index 0000000..0e142c6
--- /dev/null
+++ b/drivers/tty.h
@@ -0,0 +1,9 @@
+#include <stdint.h>
+
+void tty_init(void);
+void tty_clear(void);
+void tty_set_color(uint8_t);
+uint8_t tty_get_color(void);
+void tty_putchar_at(char ch, uint8_t color, int x, int y);
+void tty_putchar(char ch);
+void tty_puts(const char*);
diff --git a/drivers/vga.h b/drivers/vga.h
new file mode 100644
index 0000000..bf13cba
--- /dev/null
+++ b/drivers/vga.h
@@ -0,0 +1,26 @@
+#include <stdint.h>
+
+enum vga_color_t {
+    VGA_BLACK = 0,
+    VGA_BLUE = 1,
+    VGA_GREEN = 2,
+    VGA_CYAN = 3,
+    VGA_RED = 4,
+    VGA_MAGENTA = 5,
+    VGA_BROWN = 6,
+    VGA_LIGHT_GRAY = 7,
+    VGA_DARK_GRAY = 8,
+    VGA_LIGHT_BLUE = 9,
+    VGA_LIGHT_GREEN = 10,
+    VGA_LIGHT_CYAN = 11,
+    VGA_LIGHT_RED = 12,
+    VGA_LIGHT_MAGENTA = 13,
+    VGA_LIGHT_BROWN = 14,
+    VGA_WHITE = 15
+};
+
+#define VGA_WIDTH  80
+#define VGA_HEIGHT 25
+
+#define VGA_MAKE_COLOR(fg, bg) (fg | bg << 4)
+#define VGA_MAKE_ENTRY(ch, col) (((uint16_t)ch)|((uint16_t)col<<8))