Added the f_inode element to struct file as a pointer to the file's

inode in memory.

Added a jump instruction in front of the multiboot header so that the
kernel may be run as a binary image. The jump instruction will skip over
the multiboot header to the beginning of the kernel's startup procedure
in kboot.

Moved the call to initialize the timer to earlier in the boot sequence.
This is to allow for some drivers that may require it's functionality
during the startup to function properly.

Added functionality for the 'fast-gate' to the enable_a20 subroutine.
Now, if the keyboard controller method fails when enabling the gate, an
attempt is made to enable the A20 gate using the PS/2's fast-gate
interface. If this also fails, the kernel will panic.

Implemented TTY output for the console. The console is now TTY device 0
(the default for new userspace programs).

5 files changed, 58 insertions, 5 deletions

diff --git a/kernel/boot.s b/kernel/boot.s
index 8d07354..5050705 100644
--- a/kernel/boot.s
+++ b/kernel/boot.s
@@ -18,6 +18,7 @@ extern tty_init
 
 ; Multiboot header
 section .mboothdr
+jmp kboot
 mboot_hdr:
   align 4
   dd 0x1BADB002
@@ -44,10 +45,10 @@ kboot:
   call printk
   add esp, 4
   ; initialize secondary subsystems
+  call timer_init
   call fs_init
   call tty_init
   ; last minute setup, then transfer to kmain
-  call timer_init
   call kmain
   ; if kmain decides to return (which it shouldn't),
   ; disable interrupts and halt the system.
@@ -243,6 +244,14 @@ enable_a20:
   xchg ax, cx
   or al, 0x02
   out 0x60, al
+  ; check if the gate is now enabled
+  call .testgate
+  jne .end
+  ; if the gate is still not working, try the fast-gate method
+  in al, 0x92
+  and al, 0xFE
+  or al, 0x02
+  out 0x92, al
   ; make sure the gate is working (panic if not)
   call .testgate
   jne .end
@@ -272,7 +281,7 @@ enable_a20:
   pop ebp
   ret
 .tmp: dw 0xDEAD
-.msg: db "Failed to enable A20 gate!", 10, 0
+.msg: db "Failed to enable the A20 gate!", 10, 0
 
 pic_init:
   push ebp
diff --git a/kernel/con.c b/kernel/con.c
index 2000fbc..5a9d2e9 100644
--- a/kernel/con.c
+++ b/kernel/con.c
@@ -5,6 +5,7 @@
  */
 
 #include <asm/io.h>
+#include <kernel/tty.h>
 #include <stdarg.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -12,6 +13,14 @@
 #define COLS 80
 #define ROWS 25
 
+/* internal function prototypes */
+static void con_write(void);
+
+struct tty_struct tty_con = {
+  .init = NULL,
+  .write = &con_write
+};
+
 static uint8_t *vram = (uint8_t*) 0xB8000;
 static int pos;
 
@@ -91,6 +100,40 @@ static int con_puts(char *s) {
   return 0;
 }
 
+/* same as con_puts() but deals with bytes rather than strings */
+static void con_write(void) {
+  char c;
+  int copied = 0;
+  uint8_t *p = &vram[pos];
+  struct tty_queue *q = &tty_con.wqueue;
+
+  while(q->pread != q->pwrite) {
+    c = q->buf[q->pread];
+    if(c == '\n') {
+      pos = (int) (p - vram);
+      pos = ((pos / (COLS << 1)) + 1) * (COLS << 1);
+      p = &vram[pos];
+    } else {
+      *p = c;
+      p += 2;
+    }
+
+    q->pread = (q->pread + 1) % TTY_BUF_SIZE;
+    copied = 1;
+
+    pos = (int) (p - vram);
+
+    if(pos >= (COLS * ROWS) << 1)
+      scroll_up();
+  }
+
+  /* update the cursor position */
+  cursorpos(pos);
+
+  if(copied)
+    wake_up(&q->waiting);
+}
+
 int printk(char *fmt, ...) {
   int ret;
   char buf[1024];
diff --git a/kernel/hd.c b/kernel/hd.c
index eab82dc..3b2aa3c 100644
--- a/kernel/hd.c
+++ b/kernel/hd.c
@@ -183,5 +183,5 @@ void hd_init(void) {
     return;
   }
 
-  printk("[hd] Primary bus master drive initialized! (status: 0x%02x, nblocks: 0x%01x)\n", s, nblocks);
+  printk("[hd] Primary bus master drive initialized! (status: 0x%02x, nsects: 0x%01x)\n", s, nblocks);
 }
diff --git a/kernel/sched.c b/kernel/sched.c
index a17b58c..da55fa3 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -209,7 +209,7 @@ void sched_init(void) {
   ctask = NULL;
 
   create_proc(&_usrbin_start, (size_t) &_usrbin_size);
-  /* create_proc(&_usrbin_start, (size_t) &_usrbin_size); */
+  create_proc(&_usrbin_start, (size_t) &_usrbin_size);
 
   switch_to(0, &tasks[0]);
 }
diff --git a/kernel/tty.c b/kernel/tty.c
index bfbf775..529d955 100644
--- a/kernel/tty.c
+++ b/kernel/tty.c
@@ -1,5 +1,6 @@
 #include <asm/interrupt.h>
 #include <errno.h>
+#include <kernel/con.h>
 #include <kernel/sched.h>
 #include <kernel/serial.h>
 #include <kernel/tty.h>
@@ -12,7 +13,7 @@
   (sizeof(ttys) / sizeof(struct tty_struct*))
 
 static struct tty_struct *ttys[] = {
-  NULL,
+  &tty_con,
   &tty_rs
 };