Ajurna
918c9020b5
Introduced symbol files for various Game Boy systems (CGB, AGB, MGB, SGB) to define boot sequences and functionalities. Included CPU instruction behavior tests, with detailed coverage of standard operations and interrupt handling. Added documentation for test execution and internal framework operations.
292 lines
5.3 KiB
ArmAsm
292 lines
5.3 KiB
ArmAsm
; Scrolling text console
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; Console is 20x18 characters. Buffers lines, so
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; output doesn't appear until a newline or flush.
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; If scrolling isn't supported (i.e. SCY is treated
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; as if always zero), the first 18 lines will
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; still print properly). Also works properly if
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; LY isn't supported (always reads back as the same
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; value).
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.define console_width 20
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.define console_buf bss+0
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.define console_pos bss+console_width
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.define console_mode bss+console_width+1
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.define console_scroll bss+console_width+2
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.redefine bss bss+console_width+3
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; Waits for start of LCD blanking period
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; Preserved: BC, DE, HL
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console_wait_vbl:
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push bc
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; Wait for start of vblank, with
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; timeout in case LY doesn't work
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; or LCD is disabled.
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ld bc,-1250
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- inc bc
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ld a,b
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or c
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jr z,@timeout
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lda LY
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cp 144
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jr nz,-
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@timeout:
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pop bc
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ret
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; Initializes text console
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console_init:
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call console_hide
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; CGB-specific inits
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ld a,(gb_id)
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and gb_id_cgb
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call nz,@init_cgb
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; Clear nametable
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ld a,' '
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call @fill_nametable
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; Load tiles
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ld hl,TILES+$200
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ld c,0
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call @load_tiles
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ld hl,TILES+$A00
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ld c,$FF
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call @load_tiles
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; Init state
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ld a,console_width
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ld (console_pos),a
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ld a,0
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ld (console_mode),a
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ld a,-8
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ld (console_scroll),a
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call console_scroll_up_
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jr console_show
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@fill_nametable:
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ld hl,BGMAP0
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ld b,4
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- ld (hl),a
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inc l
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jr nz,-
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inc h
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dec b
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jr nz,-
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ret
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@init_cgb:
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; Clear palette
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wreg $FF68,$80
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ld b,16
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- wreg $FF69,$FF
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wreg $FF69,$7F
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wreg $FF69,$00
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wreg $FF69,$00
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wreg $FF69,$00
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wreg $FF69,$00
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wreg $FF69,$00
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wreg $FF69,$00
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dec b
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jr nz,-
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; Clear attributes
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ld a,1
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ld (VBK),a
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ld a,0
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call @fill_nametable
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ld a,0
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ld (VBK),a
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ret
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@load_tiles:
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ld de,ASCII
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ld b,96
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-- push bc
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ld b,8
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- ld a,(de)
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inc de
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xor c
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ldi (hl),a
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ldi (hl),a
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dec b
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jr nz,-
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pop bc
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dec b
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jr nz,--
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ret
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; Shows console display
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; Preserved: AF, BC, DE, HL
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console_show:
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push af
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; Enable LCD
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call console_wait_vbl
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wreg LCDC,$91
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wreg SCX,0
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wreg BGP,$E4
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jp console_apply_scroll_
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; Hides console display by turning LCD off
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; Preserved: AF, BC, DE, HL
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console_hide:
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push af
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; LCD off
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call console_wait_vbl
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wreg LCDC,$11
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pop af
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ret
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; Changes to normal text mode
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; Preserved: BC, DE, HL
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console_normal:
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xor a
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jr console_set_mode
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; Changes to inverse text mode
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; Preserved: BC, DE, HL
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console_inverse:
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ld a,$80
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; Changes console mode to A.
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; 0: Normal, $80: Inverse
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; Preserved: BC, DE, HL
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console_set_mode:
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and $80
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ld (console_mode),a
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ret
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; Prints char A to console. Will not appear until
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; a newline or flush occurs.
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; Preserved: AF, BC, DE, HL
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console_print:
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push af
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cp 10
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jr z,console_newline_
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push hl
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push af
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ld hl,console_pos
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ldi a,(hl)
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cp <console_buf
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jr nz,@not_at_end
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; Newline if at end of current line. If this
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; were done after writing to buffer, calling
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; console_newline would print extra newline.
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; Doing it before eliminates this.
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; Ignore any spaces at end of line
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pop af
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cp ' '
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jr z,@ignore_space
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call console_newline
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push af
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@not_at_end:
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pop af
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or (hl) ; apply current attributes
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dec l ; hl = console_pos
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dec (hl) ; console_pos = console_pos - 1
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ld l,(hl) ; hl = position in buffer
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ld (hl),a
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@ignore_space
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pop hl
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pop af
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ret
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; Displays current line and starts new one
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; Preserved: AF, BC, DE, HL
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console_newline:
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push af
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console_newline_:
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call console_wait_vbl
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call console_flush_
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call console_scroll_up_
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call console_flush_
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jp console_apply_scroll_
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console_scroll_up_:
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push bc
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push hl
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; Scroll up 8 pixels
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ld a,(console_scroll)
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add 8
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ld (console_scroll),a
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; Start new clear line
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ld a,' '
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ld hl,console_buf + console_width - 1
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ld b,console_width
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- ldd (hl),a
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dec b
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jr nz,-
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ld a,<(console_buf + console_width)
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ld (console_pos),a
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pop hl
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pop bc
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ret
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; Displays current line's contents without scrolling.
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; Preserved: A, BC, DE, HL
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console_flush:
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push af
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call console_wait_vbl
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call console_flush_
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console_apply_scroll_:
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ld a,(console_scroll)
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sub 136
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sta SCY
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pop af
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ret
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console_flush_:
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push de
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push hl
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; Address of row in nametable
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ld a,(console_scroll)
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ld l,a
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ld h,(>BGMAP0) >> 2
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add hl,hl
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add hl,hl
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; Copy line
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ld de,console_buf + console_width
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- dec e
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ld a,(de)
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ldi (hl),a
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ld a,e
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cp <console_buf
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jr nz,-
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pop hl
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pop de
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ret
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ASCII:
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.incbin "console.bin"
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