From 4528b2347ac72ffdabdbe4d9e7bf7789c81e664f Mon Sep 17 00:00:00 2001
From: Aleksa Vučković <aleksav013@gmail.com>
Date: Tue, 12 Oct 2021 21:53:40 +0200
Subject: Adding tty

---
 src/keyboard.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 src/keyboard.c

(limited to 'src/keyboard.c')

diff --git a/src/keyboard.c b/src/keyboard.c
new file mode 100644
index 0000000..987c7a2
--- /dev/null
+++ b/src/keyboard.c
@@ -0,0 +1,78 @@
+#include<stdbool.h>
+#include<stddef.h>
+#include<stdint.h>
+#include"keyboard.h"
+
+#define BUFFER_SIZE 200
+char buffer[BUFFER_SIZE];
+size_t buffer_index=0;
+
+#define PIC1_COMMAND_PORT 0x20
+#define PIC1_DATA_PORT 0x21
+#define PIC2_COMMAND_PORT 0xA0
+#define PIC2_DATA_PORT 0xA1
+// IO Ports for Keyboard
+#define KEYBOARD_DATA_PORT 0x60
+#define KEYBOARD_STATUS_PORT 0x64
+
+extern char ioport_in(uint8_t port);
+extern void ioport_out(uint8_t port, char data);
+
+void previous_field();
+void terminal_putchar(char c);
+void tty(char *buffer);
+void prompt();
+
+void init_keyboard()
+{
+    // 0xFD = 1111 1101 in binary. enables only IRQ1
+    // Why IRQ1? Remember, IRQ0 exists, it's 0-based
+    ioport_out(PIC1_DATA_PORT, 0xFD);
+}
+
+void backspace()
+{
+    if(buffer_index<=0) return;
+
+    previous_field();
+    terminal_putchar(' ');
+    previous_field();
+    buffer[--buffer_index]='\0';
+    return;
+}
+
+void enter()
+{
+    terminal_putchar('\n');
+    if(buffer_index>0)
+    {
+	tty(buffer);
+	for(int i=0;i<BUFFER_SIZE;i++) buffer[i]='\0';
+	buffer_index=0;
+    }
+    prompt();
+    return;
+}
+
+void handle_keyboard_interrupt()
+{
+    // Write end of interrupt (EOI)
+    ioport_out(PIC1_COMMAND_PORT, 0x20);
+    unsigned char status = ioport_in(KEYBOARD_STATUS_PORT);
+
+    // Lowest bit of status will be set if buffer not empty
+    if (status & 0x1)
+    {
+	int16_t keycode = ioport_in(KEYBOARD_DATA_PORT);
+	if (keycode < 0 || keycode >= 128) return;
+
+	if(keycode==14) backspace();
+	else if(keycode==28) enter();
+	else
+	{
+	    buffer[buffer_index++]=keyboard[keycode];
+	    terminal_putchar(keyboard[keycode]);
+	}
+
+    }
+}
-- 
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