[BOOT] Print functions for debugging

kernel/drivers/serial.c

@@ -0,0 +1,23 @@
+#include <serial.h>
+#include <ports.h>
+
+
+void serial_init(uint16_t port)
+{
+  // Serial port initialization according to
+  // http://wiki.osdev.org/Serial_Ports
+  outb(port + 1, 0x00);
+  outb(port+ 3, 0x80);
+  outb(port+ 0, 0x03);
+  outb(port+ 1, 0x00);
+  outb(port+ 3, 0x03);
+  outb(port+ 2, 0xC7);
+  outb(port+ 4, 0x0B);
+}
+
+void serial_write(uint16_t port, uint8_t c)
+{
+  while(!(inb(port+ 5)&0x20));
+
+  outb(port, c);
+}

kernel/drivers/vga.c

@@ -0,0 +1,77 @@
+#include <vga.h>
+#include <stdint.h>
+#include <stdarg.h>
+#include <string.h>
+#include <mem.h>
+#include <ports.h>
+
+
+void *vidmem = P2V(0xb8000);
+uint16_t buffer[VGA_SIZE];
+
+struct {
+  uint32_t x;
+  uint32_t y;
+  uint8_t style;
+} cursor;
+
+void sync()
+{
+  // Copy the buffer to video memory
+  memcpy(vidmem, buffer, sizeof(buffer));
+}
+
+void setcursor()
+{
+  // Move hardware cursor to correspond to the software one
+  uint16_t position = cursor.y*VGA_WIDTH + cursor.x;
+  outb(0x3D4, 0x0F);
+  outb(0x3D5, (uint8_t)(position & 0xFF));
+  outb(0x3D4, 0x0E);
+  outb(0x3D5, (uint8_t)((position >> 8) & 0xF));
+}
+
+void scroll()
+{
+  // Scroll all lines up and clear the bottom one
+  while(cursor.y >= VGA_LINES)
+  {
+    memmove(buffer, &buffer[VGA_WIDTH], sizeof(buffer)-2*VGA_WIDTH);
+    memset(&buffer[VGA_SIZE-VGA_WIDTH], 0, 2*VGA_WIDTH);
+    cursor.y--;
+  }
+}
+
+void vga_printch(char c)
+{
+  // Print a character to VGA memory
+  if(c == '\n')
+  {
+    // Linebreak
+    cursor.x = 0;
+    cursor.y++;
+  } else {
+    buffer[cursor.y*VGA_WIDTH + cursor.x] = c | (cursor.style << 8);
+    cursor.x++;
+  }
+
+  if(cursor.x >= VGA_WIDTH)
+  {
+  // Wrap line
+    cursor.x = 0;
+    cursor.y++;
+  }
+  scroll();
+  sync();
+  setcursor();
+}
+
+void vga_init()
+{
+  // Set cursor at top left
+  cursor.x = cursor.y = 0;
+  cursor.style = 0x07;
+  // Clear video memory
+  memset(buffer, 0, sizeof(buffer));
+  sync();
+}