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%ifndef _TERMINAL_ASM
%define _TERMINAL_ASM
T_BUFSZ equ 255 ; maximum length of terminal input buffer
terminal:
push bp
mov bp, sp
push ds
push es
mov ax, ds
mov es, ax
sub sp, T_BUFSZ ; reserve space for tokens
cld
.clear_buffer:
xor ax, ax
mov cx, T_BUFSZ / 2
lea di, [bp - T_BUFSZ]
mov dx, di
repne stosb ; zero out token storage
xor ax, ax
mov cx, T_BUFSZ / 2 ; counter is length of buffer
mov di, t_buffer ; destination is buffer
repne stosw ; zero buffer
.do_prompt:
xor cx, cx ; reset counter
; this tracks keyboard presses
mov al, ASCII_LF
call putc ; write carriage return to console
push t_msg_prompt ; address of prompt string
push t_msg_prompt_fmt ; address of prompt format string
call printf ; print prompt to console
add sp, 2 * 2 ; clean up stack
mov di, t_buffer ; input destination is buffer
.read_command:
call kbd_read ; get input from user
cmp al, ASCII_CR ; return pressed?
jne .update_buffer
mov al, ASCII_LF ; convert CR to LF
.update_buffer:
cmp al, ASCII_LF
je .flush_buffer ; if carriage return, flush buffer
cmp cx, T_BUFSZ
jge .read_command ; trap lines to long to fit in memory
; we cannot continue until user hits return
stosb ; write input character to buffer
inc cx ; increment character count
jmp .output ; output character (default)
.flush_buffer:
cmp [di-1], byte 0 ; stosb above increments di.
; (di - 1) is the previous input
je .do_prompt ; if no input (null), start over
mov al, ASCII_LF
call putc ; print carriage return
push ' '
push dx
push t_buffer
call strtok
add sp, 2 * 3
push ax
call printh
add sp, 2
; ---- TEMPORARY ---
; a command parser will be here eventually
; TODO: write string tokenizer
;push t_buffer ; push buffer string address
;push t_buffer_fmt ; push buffer format string address
;call printf ; write input to console
;add sp, 2 * 2 ; clean up stack
; --- END TEMPORARY ---
jmp .clear_buffer ; zero out buffer / start over
.output:
call putc
jmp .read_command ; print input to screen as we type
jmp .do_prompt ; start over
add sp, 2
pop es
pop ds
mov sp, bp
pop bp
ret
; data
t_msg_prompt_fmt: db '%s', 0
t_msg_prompt: db '$ ', 0
t_buffer_fmt: db '%s', 0
t_buffer: times T_BUFSZ db 0
%endif
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