; Instructions:

;

; ./stackvm build keyboard-input.asm -o out.bc

; ./stackvm run out.bc

; ./stackvm monitor machine.memory -s 2

;

; Focus the window opened by the monitor command

; and press some keys on your keyboard. You should now

; see some stuff popping up in the terminal off the run command

; Configure the interrupt handler's address

.org INTERRUPT_HANDLER_ADDRESS

.db _interrupt_handler_address t_address my_interrupt_handler

.org INTERRUPT_MEMORY

.db _interrupt_memory INTERRUPT_MEMORY_SIZE 0

.org 0x00

.db io_buffer 255 0

.def io_cursor r0

.label entry_addr

; execute the main function

push t_size, 0

call main

; exit the program

push byte, 0

push t_syscall, sys_exit

syscall

.label main

nop

jmp main

.label my_interrupt_handler

; skip if this is a keydown

readc r2b, INTERRUPT_KEYBOARD_KEYDOWN

loadi r3b, 1

cmp r2b, r3b

jz read_char

ret

.label read_char

; calculate the cursor offset

mov r1, io_cursor

loadi r2, io_buffer

add r1, r2

; copy the char

readc r2b, INTERRUPT_KEYBOARD_SYM

write r1, r2b

; increment the io cursor

push t_size, 0x0

call increment_io_cursor

push t_size, 0x0

call print_io_buffer

ret

.label increment_io_cursor

mov r1, io_cursor

loadi r2, 1

add r1, r2

mov io_cursor, r1

ret

.label print_io_buffer

mov r1, INTERRUPT_MEMORY

mov r2, io_cursor

add r2, r1

.label loop

cmp r1, r2

jz loop_end

rpush r1

push t_size, byte

push t_syscall, sys_write

syscall

loadi r3, 1

add r1, r3

jmp loop

.label loop_end

push byte, 13

rpush sp

push t_size, 1

push t_syscall, sys_write

syscall

loadi r59, 1

add sp, r59

ret

; Note to future self

; Somewhere is a bug which causes an invalid jump to 0x3a

; in the case when an interrupt happens inside an interrupt handler

;

; this is likely an issue of us not producing a correct stack frame

; and thus making it jump to some weird address

;

; something worth to investiage:

; 0x3a = 58 = syscall

;

; maybe the ret instruction tries to jump to an opcodes value ???