Serial input if no-LFB

- Enable serial interrupt
- Add serial interrupt handler
- `b_output_serial` will automatically output CR if LF is detected

Author: Ian Seyler

src/drivers/serial.asm

@@ -15,11 +15,26 @@ serial_init:
 	bt ax, 0			; LEGACY_DEVICES
 	jnc serial_init_error
 
-	; TODO - Enable interrupts if needed
-
 	; Set flag that Serial was enabled
 	or qword [os_SysConfEn], 1 << 2
 
+%ifdef NO_LFB
+	; Configure interrupt handler
+	mov edi, 0x24
+	mov rax, int_serial
+	call create_gate
+
+	; Enable specific interrupts
+	mov ecx, 4			; Serial IRQ
+	mov eax, 0x24			; Serial Interrupt Vector
+	call os_ioapic_mask_clear
+
+	; Enable serial port interrupts
+	mov dx, COM_PORT_INTERRUPT_ENABLE
+	mov al, 1			; Set bit 0 for Received Data Available
+	out dx, al
+%endif
+
 serial_init_error:
 	ret
 ; -----------------------------------------------------------------------------
@@ -90,6 +105,19 @@ serial_recv_backspace:
 ; -----------------------------------------------------------------------------
 
 
+; -----------------------------------------------------------------------------
+; serial_interrupt -- Receives a character via the configured serial port
+serial_interrupt:
+	push rax
+
+	call serial_recv
+	mov [key], al			; Treat the character as being from the keyboard
+
+	pop rax
+	ret
+; -----------------------------------------------------------------------------
+
+
 ; Port Registers
 COM_BASE			equ 0x3F8
 COM_PORT_DATA			equ COM_BASE + 0

src/interrupt.asm

@@ -49,6 +49,29 @@ int_keyboard:
 ; -----------------------------------------------------------------------------
 
 
+; -----------------------------------------------------------------------------
+; Serial interrupt. IRQ 0x04, INT 0x24
+; This IRQ runs whenever there is input on the serial port
+align 8
+int_serial:
+	push rcx
+	push rax
+
+	call serial_interrupt	; Call interrupt code in serial driver
+
+	; Acknowledge the IRQ
+	mov ecx, APIC_EOI
+	xor eax, eax
+	call os_apic_write
+
+	call b_smp_wakeup_all		; A terrible hack
+
+	pop rax
+	pop rcx
+	iretq
+; -----------------------------------------------------------------------------
+
+
 ; -----------------------------------------------------------------------------
 ; Mouse interrupt. IRQ 0x0C, INT 0x2C
 ; This IRQ runs whenever there is input on the mouse

src/syscalls/io.asm

@@ -7,15 +7,15 @@
 
 
 ; -----------------------------------------------------------------------------
-; b_input -- Scans keyboard for input
+; b_input -- Scans for input
 ;  IN:	Nothing
 ; OUT:	AL = 0 if no key pressed, otherwise ASCII code, other regs preserved
 ;	All other registers preserved
 b_input:
-	mov al, [key]
+	mov al, [key]			; Keyboard/Serial interrupt handler sets key
 	test al, al
 	jz b_input_no_key
-	mov byte [key], 0x00		; clear the variable as the keystroke is in AL now
+	mov byte [key], 0x00		; Clear the variable as the keystroke is in AL now
 b_input_no_key:
 	ret
 ; -----------------------------------------------------------------------------
@@ -44,6 +44,12 @@ b_output_serial:
 
 b_output_serial_next:
 	lodsb				; Load a byte from the string into AL
+	cmp al, 10			; Check for Line Feed
+	jne b_output_serial_send
+	mov al, 13			; Carriage Return
+	call serial_send
+	mov al, 10
+b_output_serial_send:
 	call serial_send		; Output it via serial
 	dec cx				; Decrement the counter
 	jnz b_output_serial_next	; Loop if counter isn't zero