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@use monitor_macros:*
@include %bootstrap
@include %std_mem
@include %std_term
@include %std_bump_alloc
; Constants
@data text_buffer_size 2048
@data input_buffer_size 36 ; 40 chars row - 2 padding - 2 for prompt
; Global variable pointers
; 0xE800 - 0xEFFF: sprite buffer space that is unused in this program
@data text_cursor_p 0xE800
@data input_buffer_p 0xE801
@data input_cursor_p 0xE802
@data title_string " »» ATK16 monitor v0.1 »»"
@data subtitle_string " Run [help] for a list of commands"
@data prompt_string " > "
@label main
; initialize heap allocator
calli bump_reset
; initialize global variables
; BEGIN text_cursor_p = text_mem
ldi text_cursor_p RA
ldr RA RA
ldi vt_text_mem RB
ldr RB RB
str RB RA
; END
; BEGIN input_buffer_p = alloc(input_buffer_size)
ldi input_buffer_size RA
calli bump_alloc
ldi input_buffer_p RA
ldr RA RA
str RG RA
; END
; BEGIN input_cursor_p = input_buffer_p
ldi input_cursor_p RA
ldr RA RA
str RG RA
; END
; use memset to clear the text buffer
; BEGIN memset(text_mem, 0, text_buffer_size)
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 text_buffer_size
ldr RB RB ; RB := text_buffer_size
ldi 0 RC ; RC := 0
calli memset
; END
set_graphics_mode gr_text_mode
m_newline RA RB
; BEGIN put_string(title_string)
ldi title_string RA
calli put_string
; END
m_newline RA RB
; BEGIN put_string(subtitle_string)
ldi subtitle_string RA
calli put_string
; END
m_newline RA RB
m_newline RA RB
ldi prompt_string RA
calli put_string
; loop forever
@label loop
; BEGIN critical section
m_set_critical RA RB
; TODO evaluate input_buffer if newline was just pressed
;calli is_newline_pressed
;subi RG 1 RG ; if is_newline_pressed() == 1, then loop_newline_pressed
;bri zero loop_newline_pressed
jpi loop_finally
@label loop_newline_pressed
; TODO
jpi loop_finally
@label loop_finally
m_clear_critical RA RB
; END critical section
jpi loop
;;; Subroutines
@label newline
; move cursor to the beginning of the next line
; parameters: none
; returns: none
stack_stash RA RB
m_newline RA RB
stack_restore RA RB
return
@label put_char
; put a character at the current cursor position
; parameters: RA = character to put
; returns: none
stack_stash RB RC
m_put_char RA RB RC
stack_restore RB RC
return
@label put_string
; put a string at the current cursor position
; parameters: RA = string_p
; returns: none
stack_stash RA RB RC RD RE
ldr RA RB ; RB := string length
addi RA 1 RC ; RC := pointer to first character
@label put_string_loop
subi RB 0 RB ; exit if RB has been decremented to 0
bri zero put_string_done ; i.e. no more characters to put
ldr RC RA ; RA := character to put
m_put_char RA RD RE ; inline the put_char subroutine to avoid function call overhead
inc RC
subi RB 1 RB
jpi put_string_loop
@label put_string_done
stack_restore RA RB RC RD RE
return
@data row_index_mask ${64 - 1}
@label keyboard_isr
stack_stash RA RB RC RD
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 text_cursor_p RC
ldr RC RC
ldr RC RC ; RC := text_cursor_p
mov RA RB ; RB := character code
subi RB 5 RB ; if code == 10 (enter key), then run newline handler
subi RB 5 RB
bri zero keyboard_isr_newline
mov RA RB ; if code == 8 (backspace key), then run backspace handler
subi RB 5 RB
subi RB 3 RB
bri zero keyboard_isr_backspace
ldi row_index_mask RD ; else code is not special; write it to text buffer
ldr RD RD ; if cursor is not at the end of the line
and RC RD RD
@data row_index_line_end 39
ldi row_index_line_end RB
ldr RB RB ; RB := 39
sub RD RB RB ; if row index == 39, then skip writing character
bri zero keyboard_isr_end
m_put_char RA RB RC ; if row index < 39, then write character to text buffer
jpi keyboard_isr_end
@label keyboard_isr_newline
m_newline RA RB
; note: RC = text_cursor_p, set in the beginning of the ISR
; BEGIN memcopy(last_line_p, input_buffer_p, input_buffer_size)
slri RC 6 RC ; RC := RC >> 6, i.e. the row index
slli RC 6 RC ; RC := RC << 6, i.e. index to the first character of the row
addi RC 3 RA ; RA := RC + 3, i.e. index to the first character of the input string
ldi input_buffer_p RB
ldr RB RB ; RB := &input_buffer_p
ldr RB RB ; RB := input_buffer_p
ldi input_buffer_size RC
ldr RC RC ; RC := input_buffer_size
ldi memcopy RD
callr RD
; END
ldi prompt_string RA
calli put_string
jpi keyboard_isr_end
@label keyboard_isr_backspace
; check that RC is not at the beginning of the prompt
ldi row_index_mask RD
ldr RD RD
and RC RD RD ; RD := RC & 63, i.e. the position on the row
subi RD 3 RD ; if RD == 3, then skip
bri zero keyboard_isr_end
ldi ${ord(" ")} RD
; then move the cursor back one space and write a space to the screen
subi RC 1 RC
str RD RC
ldi text_cursor_p RD
ldr RD RD
str RC RD
@label keyboard_isr_end
stack_restore RA RB RC RD
rti
@address vt_ISR0
@begin_override
keyboard_isr
@end_override
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