nesemu/tests/cpu_exec_space/source/common/console.s

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2023-12-03 00:27:07 -05:00
; Scrolling text console with line wrapping, 30x29 characters.
; Buffers lines for speed. Will work even if PPU doesn't
; support scrolling (until text reaches bottom). Keeps border
; along bottom in case TV cuts it off.
;
; Defers most initialization until first newline, at which
; point it clears nametable and makes palette non-black.
;
; ** ASCII font must already be in CHR, and mirroring
; must be vertical or single-screen.
; Number of characters of margin on left and right, to avoid
; text getting cut off by common TVs
console_margin = 1
console_buf_size = 32
console_width = console_buf_size - (console_margin*2)
zp_byte console_pos
zp_byte console_scroll
zp_byte console_temp
zp_byte text_color
bss_res console_buf,console_buf_size
; Initializes console
console_init:
; Flag that console hasn't been initialized
setb console_scroll,-1&$FF
lda #0
sta text_color
jmp console_clear_line_
; Hides console by blacking palette and disabling PPU.
; Preserved: A, X, Y
console_hide:
pha
txa
pha
tay
pha
jsr console_wait_vbl_
setb PPUMASK,0
lda #$0F
tax
tay
jsr console_load_palette_
pla
tay
pla
tax
pla
rts
console_wait_vbl_:
lda console_scroll
cmp #-1&$FF
jne wait_vbl_optional
; Deferred initialization of PPU until first use of console
; In case PPU doesn't support scrolling, start a
; couple of lines down
setb console_scroll,16
jsr console_hide
txa
pha
; Fill nametable with spaces
setb PPUADDR,$20
setb PPUADDR,$00
ldx #240
;lda #$E0
;sta text_color
lda #0
: sta PPUDATA
sta PPUDATA
sta PPUDATA
sta PPUDATA
dex
bne :-
; Clear attributes
lda #0
ldx #$40
: sta PPUDATA
dex
bne :-
pla
tax
jmp console_show
; Shows console display
; Preserved: X, Y
console_show:
pha
txa
pha
tay
pha
jsr console_wait_vbl_
setb PPUMASK,PPUMASK_BG0
lda #$22 ; red
ldx #$27 ; green
ldy #$30 ; white
jsr console_load_palette_
pla
tay
pla
tax
jmp console_apply_scroll_
; Shows console display
; Preserved: X, Y
console_show_nowait:
pha
txa
pha
tay
pha
setb PPUMASK,PPUMASK_BG0
lda #$22 ; red
ldx #$27 ; green
ldy #$30 ; white
jsr console_load_palette_
pla
tay
pla
tax
jmp console_apply_scroll_
console_load_palette_:
pha
setb PPUADDR,$3F
setb PPUADDR,$00
setb PPUDATA,$0F ; black
pla
sta PPUDATA
stx PPUDATA
sty PPUDATA
rts
; Prints char A to console. Will not appear until
; a newline or flush occurs.
; Preserved: A, X, Y
console_print:
cmp #10
beq console_newline
stx console_temp
; Newline if buf full and next char isn't space
ldx console_pos
bpl :+
cmp #' '
beq @ignore_space
ldx console_temp
jsr console_newline
stx console_temp
ldx console_pos
:
; Write to buffer
clc
adc text_color
sta console_buf+console_margin,x
dex
stx console_pos
@ignore_space:
ldx console_temp
rts
; Displays current line and starts new one
; Preserved: A, X, Y
console_newline:
pha
jsr console_wait_vbl_
jsr console_flush_
jsr console_clear_line_
; Scroll up 8 pixels and clear one line AHEAD
lda console_scroll
jsr console_add_8_to_scroll_
sta console_scroll
jsr console_add_8_to_scroll_
jsr console_flush_a
jmp console_apply_scroll_
; A = (A + 8) % 240
console_add_8_to_scroll_:
cmp #240-8
bcc :+
adc #16-1;+1 for set carry
: adc #8
rts
console_clear_line_:
stx console_temp
; Start new clear line
lda #0
ldx #console_buf_size-1
: sta console_buf,x
dex
bpl :-
ldx #console_width-1
stx console_pos
ldx console_temp
rts
; Displays current line's contents without scrolling.
; Preserved: A, X, Y
console_flush:
pha
jsr console_wait_vbl_
jsr console_flush_
console_apply_scroll_:
lda #0
sta PPUADDR
sta PPUADDR
sta PPUSCROLL
lda console_scroll
jsr console_add_8_to_scroll_
jsr console_add_8_to_scroll_
sta PPUSCROLL
pla
rts
console_flush_:
lda console_scroll
console_flush_a:
; Address line in nametable
sta console_temp
lda #$08
asl console_temp
rol a
asl console_temp
rol a
sta PPUADDR
lda console_temp
sta PPUADDR
; Copy line
stx console_temp
ldx #console_buf_size-1
: lda console_buf,x
sta PPUDATA
dex
bpl :-
ldx console_temp
rts