Add: read keyboard input (getch)

src/kernel/kb.c

@@ -2,6 +2,8 @@
 #include "../libc/stdio.h"
 #include "system.h"
 
+#define KEYBOARD_BUFFER_SIZE 256
+
 unsigned char kbdus[128] =
 {
     0,  27, '1', '2', '3', '4', '5', '6', '7', '8',	/* 9 */
@@ -42,6 +44,10 @@ unsigned char kbdus[128] =
     0,	/* All other keys are undefined */
 };
 
+static char keyboard_buffer[KEYBOARD_BUFFER_SIZE];
+static unsigned int keyboard_buffer_start = 0;
+static unsigned int keyboard_buffer_end = 0;
+
 void keyboard_handler()
 {
 	unsigned char scancode;
@@ -53,7 +59,12 @@ void keyboard_handler()
 	}
 	else 
 	{
-		putc(kbdus[scancode]);
+		char c = kbdus[scancode];
+		if (c)
+		{
+			keyboard_buffer[keyboard_buffer_end] = c;
+			keyboard_buffer_end = (keyboard_buffer_end+1) % KEYBOARD_BUFFER_SIZE;
+		}
 	}
 }
 
@@ -61,3 +72,12 @@ void keyboard_install()
 {
 	irq_install_handler(1, keyboard_handler);
 }
+
+char keyboard_getchar()
+{
+	while (keyboard_buffer_start == keyboard_buffer_end);
+
+	char c = keyboard_buffer[keyboard_buffer_start];
+	keyboard_buffer_start = (keyboard_buffer_start+1) % KEYBOARD_BUFFER_SIZE;
+	return c;
+}