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@use ext_string_io:*
@include %bootstrap
@include %std_mem
@data text_buffer_size 2048
@label main
; use memset to clear the text buffer
ldi vt_text_mem RA ; RA := text buffer address pointer
ldr RA RA ; RA := text buffer address
ldi text_buffer_size RB ; RB := pointer to 1024
ldr RB RB ; RB := 1024
ldi 0 RC ; RC := 0
calli memset
cursor_to_line RC 1
put_string RC RB " »» ATK16 monitor v0.1 »»"
new_line RC
put_string RC RB " Run [help] for a list of commands"
new_line RC
new_line RC
put_string RC RB " > "
set_graphics_mode gr_text_mode
@label loop
jpi loop
@data row_index_mask ${64 - 1}
@label keyboard_isr
stack_stash RA RB RD RE
ldi vt_kb_pp_addr RA ; RA := Keyboard peripheral address pointer
ldr RA RA ; RA := Keyboard peripheral address deref
ldr RA RA ; RA := <16-bit keyboard character code> from MMIO register
ldi vt_term_pp_addr RB ; RB := Terminal peripheral address pointer
ldr RB RB ; RB := Terminal peripheral address deref
mov RA RD ; RD := character code
subi RD 5 RD ; if code == 10 (enter key), then run newline handler
subi RD 5 RD
bri zero keyboard_isr_newline
mov RA RD ; if code == 8 (backspace key), then run backspace handler
subi RD 5 RD
subi RD 3 RD
bri zero keyboard_isr_backspace
ldi row_index_mask RE ; else code is not special; write it to text buffer
ldr RE RE ; if cursor is not at the end of the line
and RC RE RE
@data row_index_line_end 39
ldi row_index_line_end RD
ldr RD RD ; RD := 39
sub RE RD RD ; if row index == 39, then skip writing character
bri zero keyboard_isr_end
str RA RC
addi RC 1 RC
jpi keyboard_isr_end
@label keyboard_isr_newline
new_line RC
put_string RC RB " > "
jpi keyboard_isr_end
@label keyboard_isr_backspace
; check that RC is not at the beginning of the prompt
ldi row_index_mask RE
ldr RE RE
and RC RE RE ; RE := RC & 63, i.e. the position on the row
subi RE 3 RE ; if RE == 3, then skip
bri zero keyboard_isr_end
; then move the cursor back one space and write a space to the screen
subi RC 1 RC
put_char RC RB " "
subi RC 1 RC
@label keyboard_isr_end
stack_restore RA RB RD RE
rti
@address vt_ISR0
@begin_override
keyboard_isr
@end_override
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