removed pdclib, strange things were happening..., user shell kinda works now

kernel/kbd.c

@@ -0,0 +1,84 @@
+#include "kbd.h"
+#include "process.h"
+#include "scheduler.h"
+#include "common.h"
+
+#include <lib/tasks.h>
+#include <lib/print.h>
+
+#include <stddef.h>
+
+#define KBD_BUFFER_SIZE 256
+
+static spinlock_t kbd_lock = {0};
+static process_t* kbd_waiting_task = NULL;
+
+static char kbd_buffer[KBD_BUFFER_SIZE];
+static int kbd_head = 0;
+static int kbd_tail = 0;
+
+static void lock_kbd() {
+    disable_interrupts();
+    spin_lock(&kbd_lock);
+}
+
+static void unlock_kbd() {
+    spin_unlock(&kbd_lock);
+    enable_interrupts();
+}
+
+static void kbd_set_waiting(process_t* task) {
+    lock_kbd();
+    if (kbd_head == kbd_tail) {
+        kbd_waiting_task = task;
+    }
+    unlock_kbd();
+}
+
+static char kbd_pop() {
+    char c = 0;
+    lock_kbd();
+    if (kbd_head != kbd_tail) {
+        c = kbd_buffer[kbd_tail];
+        kbd_tail = (kbd_tail + 1) % KBD_BUFFER_SIZE;
+    }
+    unlock_kbd();
+    return c;
+}
+
+void kbd_push(char c) {
+    spin_lock(&kbd_lock);
+    // push to buffer first, very important
+    int next_head = (kbd_head + 1) % KBD_BUFFER_SIZE;
+    if (next_head != kbd_tail) {
+        kbd_buffer[kbd_head] = c;
+        kbd_head = next_head;
+    }
+
+    if (kbd_waiting_task != NULL) {
+        wake(kbd_waiting_task);
+        kbd_waiting_task = NULL;
+    }
+    spin_unlock(&kbd_lock);
+}
+
+int kbd_ready() {
+    int ready = 0;
+    lock_kbd();
+    ready = (kbd_head != kbd_tail);
+    unlock_kbd();
+    return ready;
+}
+
+void kbd_wait() {
+    process_t* task = current_task();
+    while (!kbd_ready()) {
+        task->state = STATE_BLOCKED;
+        kbd_set_waiting(task);
+        yield();
+    }
+}
+
+char kbd_read() {
+    return kbd_pop();
+}