mirror of
https://github.com/hsoft/collapseos.git
synced 2024-11-10 02:18:04 +11:00
351 lines
7.2 KiB
NASM
351 lines
7.2 KiB
NASM
; lcd
|
|
;
|
|
; Implement PutC on TI-84+ (for now)'s LCD screen.
|
|
;
|
|
; The screen is 96x64 pixels. The 64 rows are addressed directly with CMD_ROW
|
|
; but columns are addressed in chunks of 6 or 8 bits (there are two modes).
|
|
;
|
|
; In 6-bit mode, there are 16 visible columns. In 8-bit mode, there are 12.
|
|
;
|
|
; Note that "X-increment" and "Y-increment" work in the opposite way than what
|
|
; most people expect. Y moves left and right, X moves up and down.
|
|
;
|
|
; *** Z-Offset ***
|
|
;
|
|
; This LCD has a "Z-Offset" parameter, allowing to offset rows on the
|
|
; screen however we wish. This is handy because it allows us to scroll more
|
|
; efficiently. Instead of having to copy the LCD ram around at each linefeed
|
|
; (or instead of having to maintain an in-memory buffer), we can use this
|
|
; feature.
|
|
;
|
|
; The Z-Offet goes upwards, with wrapping. For example, if we have an 8 pixels
|
|
; high line at row 0 and if our offset is 8, that line will go up 8 pixels,
|
|
; wrapping itself to the bottom of the screen.
|
|
;
|
|
; The principle is this: The active line is always the bottom one. Therefore,
|
|
; when active row is 0, Z is FNT_HEIGHT+1, when row is 1, Z is (FNT_HEIGHT+1)*2,
|
|
; When row is 8, Z is 0.
|
|
;
|
|
; *** 6/8 bit columns and smaller fonts ***
|
|
;
|
|
; If your glyphs, including padding, are 6 or 8 pixels wide, you're in luck
|
|
; because pushing them to the LCD can be done in a very efficient manner.
|
|
; Unfortunately, this makes the LCD unsuitable for a Collapse OS shell: 6
|
|
; pixels per glyph gives us only 16 characters per line, which is hardly
|
|
; usable.
|
|
;
|
|
; This is why we have this buffering system. How it works is that we're always
|
|
; in 8-bit mode and we hold the whole area (8 pixels wide by FNT_HEIGHT high)
|
|
; in memory. When we want to put a glyph to screen, we first read the contents
|
|
; of that area, then add our new glyph, offsetted and masked, to that buffer,
|
|
; then push the buffer back to the LCD. If the glyph is split, move to the next
|
|
; area and finish the job.
|
|
;
|
|
; That being said, it's important to define clearly what CURX and CURY variable
|
|
; mean. Those variable keep track of the current position *in pixels*, in both
|
|
; axes.
|
|
;
|
|
; *** Requirements ***
|
|
; fnt/mgm
|
|
;
|
|
; *** Constants ***
|
|
.equ LCD_PORT_CMD 0x10
|
|
.equ LCD_PORT_DATA 0x11
|
|
|
|
.equ LCD_CMD_6BIT 0x00
|
|
.equ LCD_CMD_8BIT 0x01
|
|
.equ LCD_CMD_DISABLE 0x02
|
|
.equ LCD_CMD_ENABLE 0x03
|
|
.equ LCD_CMD_XDEC 0x04
|
|
.equ LCD_CMD_XINC 0x05
|
|
.equ LCD_CMD_YDEC 0x06
|
|
.equ LCD_CMD_YINC 0x07
|
|
.equ LCD_CMD_COL 0x20
|
|
.equ LCD_CMD_ZOFFSET 0x40
|
|
.equ LCD_CMD_ROW 0x80
|
|
.equ LCD_CMD_CONTRAST 0xc0
|
|
|
|
; *** Variables ***
|
|
; Current Y position on the LCD, that is, where re're going to spit our next
|
|
; glyph.
|
|
.equ LCD_CURY LCD_RAMSTART
|
|
; Current X position
|
|
.equ LCD_CURX @+1
|
|
; two pixel buffers that are 8 pixels wide (1b) by FNT_HEIGHT pixels high.
|
|
; This is where we compose our resulting pixels blocks when spitting a glyph.
|
|
.equ LCD_BUF @+1
|
|
.equ LCD_RAMEND @+FNT_HEIGHT*2
|
|
|
|
; *** Code ***
|
|
lcdInit:
|
|
; Initialize variables
|
|
xor a
|
|
ld (LCD_CURY), a
|
|
ld (LCD_CURX), a
|
|
|
|
; Clear screen
|
|
call lcdClrScr
|
|
|
|
; We begin with a Z offset of FNT_HEIGHT+1
|
|
ld a, LCD_CMD_ZOFFSET+FNT_HEIGHT+1
|
|
call lcdCmd
|
|
|
|
; Enable the LCD
|
|
ld a, LCD_CMD_ENABLE
|
|
call lcdCmd
|
|
|
|
; Hack to get LCD to work. According to WikiTI, we're not sure why TIOS
|
|
; sends these, but it sends it, and it is required to make the LCD
|
|
; work. So...
|
|
ld a, 0x17
|
|
call lcdCmd
|
|
ld a, 0x0b
|
|
call lcdCmd
|
|
|
|
; Set some usable contrast
|
|
ld a, LCD_CMD_CONTRAST+0x34
|
|
call lcdCmd
|
|
|
|
; Enable 8-bit mode.
|
|
ld a, LCD_CMD_8BIT
|
|
call lcdCmd
|
|
|
|
ret
|
|
|
|
; Wait until the lcd is ready to receive a command
|
|
lcdWait:
|
|
push af
|
|
.loop:
|
|
in a, (LCD_PORT_CMD)
|
|
; When 7th bit is cleared, we can send a new command
|
|
rla
|
|
jr c, .loop
|
|
pop af
|
|
ret
|
|
|
|
; Send cmd A to LCD
|
|
lcdCmd:
|
|
out (LCD_PORT_CMD), a
|
|
jr lcdWait
|
|
|
|
; Send data A to LCD
|
|
lcdDataSet:
|
|
out (LCD_PORT_DATA), a
|
|
jr lcdWait
|
|
|
|
; Get data from LCD into A
|
|
lcdDataGet:
|
|
in a, (LCD_PORT_DATA)
|
|
jr lcdWait
|
|
|
|
; Turn LCD off
|
|
lcdOff:
|
|
push af
|
|
ld a, LCD_CMD_DISABLE
|
|
call lcdCmd
|
|
out (LCD_PORT_CMD), a
|
|
pop af
|
|
ret
|
|
|
|
; Set LCD's current column to A
|
|
lcdSetCol:
|
|
push af
|
|
; The col index specified in A is compounded with LCD_CMD_COL
|
|
add a, LCD_CMD_COL
|
|
call lcdCmd
|
|
pop af
|
|
ret
|
|
|
|
; Set LCD's current row to A
|
|
lcdSetRow:
|
|
push af
|
|
; The col index specified in A is compounded with LCD_CMD_COL
|
|
add a, LCD_CMD_ROW
|
|
call lcdCmd
|
|
pop af
|
|
ret
|
|
|
|
; Send the glyph that HL points to to the LCD, at its current position.
|
|
; After having called this, the LCD's position will have advanced by one
|
|
; position
|
|
lcdSendGlyph:
|
|
push af
|
|
push bc
|
|
push hl
|
|
push ix
|
|
|
|
ld a, (LCD_CURY)
|
|
call lcdSetRow
|
|
ld a, (LCD_CURX)
|
|
srl a \ srl a \ srl a ; div by 8
|
|
call lcdSetCol
|
|
|
|
; First operation: read the LCD memory for the "left" side of the
|
|
; buffer. We assume the right side to always be empty, so we don't
|
|
; read it. After having read each line, compose it with glyph line at
|
|
; HL
|
|
|
|
; Before we start, what is our bit offset?
|
|
ld a, (LCD_CURX)
|
|
and 0b111
|
|
; that's our offset, store it in C
|
|
ld c, a
|
|
|
|
ld a, LCD_CMD_XINC
|
|
call lcdCmd
|
|
ld ix, LCD_BUF
|
|
ld b, FNT_HEIGHT
|
|
; A dummy read is needed after a movement.
|
|
call lcdDataGet
|
|
.loop1:
|
|
; let's go get that glyph data
|
|
ld a, (hl)
|
|
ld (ix), a
|
|
call .shiftIX
|
|
; now let's go get existing pixel on LCD
|
|
call lcdDataGet
|
|
; and now let's do some compositing!
|
|
or (ix)
|
|
ld (ix), a
|
|
inc hl
|
|
inc ix
|
|
djnz .loop1
|
|
|
|
; Buffer set! now let's send it.
|
|
ld a, (LCD_CURY)
|
|
call lcdSetRow
|
|
|
|
ld hl, LCD_BUF
|
|
ld b, FNT_HEIGHT
|
|
.loop2:
|
|
ld a, (hl)
|
|
call lcdDataSet
|
|
inc hl
|
|
djnz .loop2
|
|
|
|
; And finally, let's send the "right side" of the buffer
|
|
ld a, (LCD_CURY)
|
|
call lcdSetRow
|
|
ld a, (LCD_CURX)
|
|
srl a \ srl a \ srl a ; div by 8
|
|
inc a
|
|
call lcdSetCol
|
|
|
|
ld hl, LCD_BUF+FNT_HEIGHT
|
|
ld b, FNT_HEIGHT
|
|
.loop3:
|
|
ld a, (hl)
|
|
call lcdDataSet
|
|
inc hl
|
|
djnz .loop3
|
|
|
|
; Increase column and wrap if necessary
|
|
ld a, (LCD_CURX)
|
|
add a, FNT_WIDTH+1
|
|
ld (LCD_CURX), a
|
|
cp 96-FNT_WIDTH
|
|
jr c, .skip ; A < 96-FNT_WIDTH
|
|
call lcdLinefeed
|
|
.skip:
|
|
pop ix
|
|
pop hl
|
|
pop bc
|
|
pop af
|
|
ret
|
|
; Shift glyph in (IX) to the right C times, sending carry into (IX+FNT_HEIGHT)
|
|
.shiftIX:
|
|
dec c \ inc c
|
|
ret z ; zero? nothing to do
|
|
push bc ; --> lvl 1
|
|
xor a
|
|
ld (ix+FNT_HEIGHT), a
|
|
.shiftLoop:
|
|
srl (ix)
|
|
rr (ix+FNT_HEIGHT)
|
|
dec c
|
|
jr nz, .shiftLoop
|
|
pop bc ; <-- lvl 1
|
|
ret
|
|
|
|
; Changes the current line and go back to leftmost column
|
|
lcdLinefeed:
|
|
push af
|
|
ld a, (LCD_CURY)
|
|
call .addFntH
|
|
ld (LCD_CURY), a
|
|
call lcdClrLn
|
|
; Now, lets set Z offset which is CURROW+FNT_HEIGHT+1
|
|
call .addFntH
|
|
add a, LCD_CMD_ZOFFSET
|
|
call lcdCmd
|
|
xor a
|
|
ld (LCD_CURX), a
|
|
pop af
|
|
ret
|
|
.addFntH:
|
|
add a, FNT_HEIGHT+1
|
|
cp 64
|
|
ret c ; A < 64? no wrap
|
|
; we have to wrap around
|
|
xor a
|
|
ret
|
|
|
|
; Clears B rows starting at row A
|
|
; B is not preserved by this routine
|
|
lcdClrX:
|
|
push af
|
|
call lcdSetRow
|
|
.outer:
|
|
push bc ; --> lvl 1
|
|
ld b, 11
|
|
ld a, LCD_CMD_YINC
|
|
call lcdCmd
|
|
xor a
|
|
call lcdSetCol
|
|
.inner:
|
|
call lcdDataSet
|
|
djnz .inner
|
|
ld a, LCD_CMD_XINC
|
|
call lcdCmd
|
|
xor a
|
|
call lcdDataSet
|
|
pop bc ; <-- lvl 1
|
|
djnz .outer
|
|
pop af
|
|
ret
|
|
|
|
lcdClrLn:
|
|
push bc
|
|
ld b, FNT_HEIGHT+1
|
|
call lcdClrX
|
|
pop bc
|
|
ret
|
|
|
|
lcdClrScr:
|
|
push bc
|
|
ld b, 64
|
|
call lcdClrX
|
|
pop bc
|
|
ret
|
|
|
|
lcdPutC:
|
|
cp LF
|
|
jp z, lcdLinefeed
|
|
cp BS
|
|
jr z, .bs
|
|
push hl
|
|
call fntGet
|
|
jr nz, .end
|
|
call lcdSendGlyph
|
|
.end:
|
|
pop hl
|
|
ret
|
|
.bs:
|
|
ld a, (LCD_CURX)
|
|
or a
|
|
ret z ; going back one line is too complicated.
|
|
; not implemented yet
|
|
sub FNT_WIDTH+1
|
|
ld (LCD_CURX), a
|
|
ret
|