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antoine-source/4play/GR.DRIVER.S

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*
* A simple GR driver
* (c) 2016, Brutal Deluxe Software
* http://www.brutaldeluxe.fr/
*
* Use them at your own risk ;-)
*
mx %11
org $1800
lst off
*---------- Some info
*
* The GR page is similar to the 40-col screen
*
* There are two pixels per byte:
* - four high bits for the first pixel
* - four low bits for the second pixel
* - and so on...
* So, we have 40x48 pixels and 16 colors
*
* The routines are not optimized!
*
*---------- Entry point
jmp GROn ; Turn GR on
jmp GROff ; Turn GR off
jmp GRClear ; Clear screen
jmp GRPutPixel ; Draw a pixel on screen
jmp GRPutPixel2 ; Alt draw a pixel on screen
jmp GRGetPixel ; Get the color of a pixel on screen
jmp GRGetPixel2 ; Alt get the color of a pixel on screen
jmp GRSetColor ; Set the pen color
jmp GRSetXY ; Set X1/Y1 coordinates
jmp GRSetXY2 ; Set X2/Y2 coordinates
jmp GRSetPage ; Set page1/page2 data
jmp GRDrawHLine ; Draw an horizontal line
jmp GRDrawHLine2 ; Alt draw an horizontal line
jmp GRDrawVLine ; Draw a vertical line
jmp GRDrawVLine2 ; Alt draw a vertical line
*---------- Information
asc 8d
asc "GR routines v1.0"8d
asc "(c) 2016, Brutal Deluxe"
asc 8d
*---------- Equates
maskHIGH = %11110000 ; Get high bits
maskLOW = %00001111 ; Get low bits
page1 = $04 ; High RAM ptr of GR page 1 ($400..$7FF)
page2 = $08 ; same for page 2 ($800..$BFF)
dpSCREEN = $fe ; My usage of the zero page ;-)
minX = 0 ; 80px wide
maxX = 40
minY = 0 ; 48px height
maxY = 48
*--- Values
theCOLOR ds 1 ; color of
theCOLORHIGH ds 1 ; color for high bits (2 pixels per byte)
theCOLORFULL ds 1 ; 8-bit color (ORA of the two previous)
theX1 ds 1 ; where to draw a point
theY1 ds 1 ; again
theX2 ds 1 ; same for H and V lines
theY2 ds 1
thePAGE ds 1 ; may contain $04 (page 1) or $08 (page 2)
*--- Softswitches
KBD = $c000 ; the first softswitch
CLR80COL = $c000
SET80COL = $c001
RDMAINRAM = $c002
RDCARDRAM = $c003
WRMAINRAM = $c004
WRCARDRAM = $c005
SETSLOTCXROM = $c006
SETINTCXROM = $c007
SETSTDZP = $c008
SETALTZP = $c009
SETINTC3ROM = $c00a
SETSLOTC3ROM = $c00b
CLR80VID = $c00c
SET80VID = $c00d
TXTCLR = $c050
TXTSET = $c051
MIXCLR = $c052
MIXSET = $c053
TXTPAGE1 = $c054
TXTPAGE2 = $c055
LORES = $c056
HIRES = $c057
SETAN3 = $c05e
CLRAN3 = $c05f
*---------- Tables
ptrSCRl hex 0080008000800080
hex 28a828a828a828a8
hex 50d050d050d050d0
ptrSCRh hex 0000010102020303
hex 0000010102020303
hex 0000010102020303
*---------------------------
* GROn
* Turn the GR screen on
* Current video conf is not saved
*
GROn = *
sta TXTCLR ; switch in graphics (not text)
sta MIXCLR ; clear mixed mode
sta TXTPAGE1 ; force page 1
sta LORES ; low-resolution graphics
lda #page1 ; exit by forcing page 1
jmp GRSetPage
*---------------------------
* GROff
* Turn the GR screen off
* Previous video conf is not restored
*
GROff = *
sta TXTPAGE1 ; switch in text page 1
sta MIXSET ; set mixed mode (4 lines text)
sta TXTSET ; switch in text (not graphics)
rts
*---------------------------
* GRClear
* Clear the entire GR screen
* with color A (ie. HOME)
*
* We preserve the text holes
* - $0x00..$0x77
* - $0x80..$0xF7
*
GRClear = *
jsr GRSetColor ; set the colors
lda #0 ; point to the first page
sta dpSCREEN ; of the GR screen
lda thePAGE ; on PAGE1 or PAGE2
sta dpSCREEN+1
lda theCOLORFULL ; get the full 8-bit color
ldx #4-1 ; number of pages to clear
clear2 ldy #127-8 ; we clear the RAM page
]lp sta (dpSCREEN),y
dey
bpl ]lp
ldy #255-8 ; we clear the RAM page
]lp sta (dpSCREEN),y
dey
bmi ]lp
inc dpSCREEN+1 ; next page
dex ; until the
bpl clear2 ; four are done
rts ; we're done
*---------------------------
* GRPutPixel / GRPutPixel2
* Draw a pixel on screen
* of color A and coords X,Y
*
GRPutPixel = *
jsr GRSetColor ; Save color
stx theX1 ; and coordinates
sty theY1
GRPutPixel2 = *
lda theY1 ; Set the RAM pointer
lsr ; of the Y line
php ; save the carry!
tax
lda ptrSCRl,x
sta dpSCREEN
lda ptrSCRh,x
clc
adc thePAGE ; don't forget the page
sta dpSCREEN+1
*--- Put a pixel
ldy theX1 ; Now, determine where to put the pixel
plp ; we restore the carry to
bcs putpixel2 ; determine where to put the pixel
*--- Put in low bits
lda (dpSCREEN),y ; get the pixel
and #maskHIGH ; keep high bits
ora theCOLOR ; add the color
sta (dpSCREEN),y ; put the pixel
rts
*--- Put in high bits
putpixel2 lda (dpSCREEN),y ; get the pixel
and #maskLOW ; keep low bits
ora theCOLORHIGH ; add the color
sta (dpSCREEN),y ; put the color
rts
*---------------------------
* GRGetPixel / GRGetPixel2
* Get the color of a pixel
* at coords X,Y and return
* it in the Accumulator
*
GRGetPixel = *
stx theX1
sty theY1
GRGetPixel2 = *
lda theY1 ; Set the RAM pointer
lsr ; of the Y line
php ; save the carry!
tax
lda ptrSCRl,x
sta dpSCREEN
lda ptrSCRh,x
clc
adc thePAGE ; don't forget the page
sta dpSCREEN+1
*--- Get a pixel
ldy theX1 ; Now, determine where to get the pixel
plp ; we restore the carry to
bcs getpixel2 ; determine where to get the pixel
*--- Get in low bits
lda (dpSCREEN),y ; get the pixel
and #maskLOW ; keep high bits
rts
*--- Get in high bits
getpixel2 lda (dpSCREEN),y ; get the pixel
and #maskHIGH ; keep high bits
lsr
lsr
lsr
lsr ; and return
rts
*---------------------------
* GRSetColor
* Define the pen color
* provided in the Accumulator
*
GRSetColor = *
and #maskLOW ; keep low 4 bits
sta theCOLOR ; save color
asl ; calculate
asl ; color for
asl ; other pixel
asl ; in the same byte
sta theCOLORHIGH ; save it
ora theCOLOR ; add lower color
sta theCOLORFULL ; save the full one
rts
*---------------------------
* GRSetXY
* Set X/Y coords for all actions
* through registers X and Y
*
GRSetXY = *
stx theX1
sty theY1
rts
*---------------------------
* GRSetXY2
* Set X2/Y2 coords for line drawing
* through registers X and Y
*
GRSetXY2 = *
stx theX2
sty theY2
rts
*---------------------------
* GRSetPage
* Set PAGE1 or PAGE2
* as the default GR screen
* The routine does not force
* the page, it sets a value only
*
GRSetPage = *
sta thePAGE
rts
*---------------------------
* GRDrawHLine / GRDrawHLine2
* Draw a line of color A
* from X1/Y1 to coords in registers X/Y
*
* Incorrect coordinates are NOT checked
*
GRDrawHLine = *
jsr GRSetColor
stx theX2
sty theY2
GRDrawHLine2 = *
lda theY1 ; are Y the same?
cmp theY2
beq drawh1
sec ; error
rts
drawh1 lda theX2 ; X2>X1?
cmp theX1
bcs drawh2 ; OK
ldx theX1 ; exchange
stx theX2 ; the two
sta theX1 ; X coords
drawh2 jsr GRPutPixel2 ; put a pixel
inc theX1 ; next X
lda theX1
cmp theX2 ; until the last
bcc drawh2
beq drawh2
rts
*---------------------------
* GRDrawVLine / GRDrawVLine2
* Draw a line of color A
* from X1/Y1 to coords in registers X/Y
*
* Incorrect coordinates are NOT checked
*
GRDrawVLine = *
jsr GRSetColor
stx theX2
sty theY2
GRDrawVLine2 = *
lda theX1 ; are X the same?
cmp theX2
beq drawv1
sec ; error
rts
drawv1 lda theY2 ; Y2>Y1?
cmp theY1
bcs drawv2 ; OK
ldx theY1 ; exchange
stx theY2 ; the two
sta theY1 ; Y coords
drawv2 jsr GRPutPixel2 ; put a pixel
inc theY1 ; next Y
lda theY1
cmp theY2 ; until the last
bcc drawv2
beq drawv2
rts
*--- End of code
ds \
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