2010-06-20, 11:46 PM
Updated version. This allows you to turn OVER on and off (so you can merge characters without them destroying bits of each other. There's another example included that might have a familiar character in it).
It also shows this is NOT really fast enough for sprites. 8 calls gets flickery...
This version adds the OVER parameter: 0 for overprint, 1 for merge.
It also shows this is NOT really fast enough for sprites. 8 calls gets flickery...
This version adds the OVER parameter: 0 for overprint, 1 for merge.
Code:
SUB HRPrint (x as uByte, y as uByte, char as uInteger, attribute as uByte, overprint as uByte)
'High res Printing, based on code produced, with thanks, by Turkwel over on the WOS boards.
'Brought to ZX Basic by Britlion, June 2010.
asm
ld a,(IX+13)
AND a
JR Z,HRP_No_Over
LD a,182
JP HRP_Change_Code
HRP_No_Over:
LD a,0
HRP_Change_Code:
LD (HRPOver1),a
LD (HRPOver2),a
ld b,(IX+7)
ld c,(IX+5)
push BC ; save our co-ordinates.
;print_char:
ld d,(IX+09)
inc d
dec d
jr z, HRPrint_From_Charset
ld e,(IX+08)
jp HR_Print
HRPrint_From_Charset:
ld de,(23606)
ld h,0
ld l,(IX+8) ; character
add hl,hl
add hl,hl
add hl,hl
add hl,de
HR_Print:
call HRPat
;convert the Y and X pixel values to the correct Screen Address - Address in DE
ld a,8
;set counter to 8 - Bytes of Character Data to put down
HRPrint0:
push af
;save off Counter
ld a,b
cp 192
jr c,HRprint1
pop af
jp HRPrintEnd
;don't print character if > 191 - off the bottom of the screen - restore AF and exit Print routine
;[this can be removed if you are keeping tight control of your Y values]
HRprint1:
push hl
push de
push de
;save off Address of Character Data, Screen Address, Screen Address
ld a,c
and 7
ld d,a
;get lowest 3 bits of Screen address
ld e,255
;set up E with the Mask to use - 11111111b = All On
ld a,(hl)
jr z,HRprint3
;get a Byte of Character Data to put down - but ignore the following Mask shifting
;if the the X value is on an actual Character boundary i.e. there's no need to shift anything
HRprint2:
rrca
srl e
dec d
jp nz,HRprint2
;Rotate the Character Data Byte D times - and Shift the Mask Byte as well, forcing Zeroes into the
;Left hand side. The Mask will be used to split the Rotated Character Data over a Character boundary
HRprint3:
pop hl
;POP one of the Screen Addresses (formerly in DE) into HL
ld d,a
ld a,e
and d
HRPOver1: or (hl)
ld (hl),a
;take the Rotated Character Data, mask it with the Mask Byte and the OR it with what's already on the Screen,
;this takes care of the first part of the Byte
;[remove the OR (HL) if you just want a straight write rather than a merge]
inc l
ld a,l
and 31
jr z,HRprint4
;Increment the Screen Address and check to see if it's at the end of a line,
;if so then there's no need to put down the second part of the Byte
ld a,e
cpl
and d
HRPOver2: or (hl)
ld (hl),a
;Similar to the first Byte, we need to Invert the mask with a CPL so we can put down the second part of the Byte
;in the next Character location
;[again, remove the OR (HL) if you just want a straight write rather than a merge]
HRprint4:
pop de
inc d
inc b
;get the Screen Address back into DE, increment the MSB so it points the the Address immediately below
;it and Increment the Y value in B as well
ld a,b
and 7
call z,HRPat
;now check if the Y value has gone over a Character Boundary i.e. we will need to recalculate the Screen
;Address if we've jumped from one Character Line to another - messy but necessary especially for lines 7 and 15
pop hl
inc hl
;get the Address of the Character Data back and increment it ready for the next byte of data
pop af
dec a
jp nz,HRPrint0
;get the Counter value back, decrement it and go back for another write if we haven't reached the end yet
jp HRPrintAttributes
;HRPAT is a subroutine to convert pixel values into an absolute screen address
;On Entry - B = Y Value C = X Value On Exit - DE = Screen Address
HRPat:
ld a,b
srl a
srl a
srl a
ld e,a
and 24
or 64
ld d,a
ld a,b
and 7
add a,d
ld d,a
ld a,e
and 7
rrca
rrca
rrca
ld e,a
ld a,c
srl a
srl a
srl a
add a,e
ld e,a
ret
HRPrintAttributes:
POP BC ; recover our X-Y co-ordinates.
ld d,0
ld a,(IX+11) ; attribute
and a
jr z, HRPrintEnd ; if attribute=0, then we don't do attributes.
ld e,a ; pass to e
;transfer Attribute Byte to e for easier use
ld a,b
cp 192
jr nc, HRPrintEnd
;check Y position and exit if off bottom of screen
push bc
;save off Y and X values for later
and 248
ld h,22
ld l,a
add hl,hl
add hl,hl
srl c
srl c
srl c
ld b,d
add hl,bc
;calculate the correct Attribute Address for the Y\X values
ld (hl),e
;set the Attribute - this is ALWAYS set no matter what the valid Y\X values used
pop bc
;get the Y and X values back into BC
;call print_attribute2
;call the subroutine to see if an adjacent Horizontal Attribute needs to be set
print_attributes1:
ld a,c
cp 248
jr nc,endPrintAttributes1
;check to see if we are at Horizontal character 31 - if so then no need to set adjacent Horizontal Attribute
and 7
jr z, endPrintAttributes1
;and don't set the adjacent Horizontal Attribute if there's no need to
inc l
ld (hl),e
dec l
;increment the Attribute address - set the adjacent horizontal Attribute - then set the Attribute Address back
endPrintAttributes1:
;
ld a,b
cp 184
jr nc, HRPrintEnd
;check to see if we are at Vertical character 23 - if so then no need to set adjacent Vertical Attribute & Exit routine
and 7
jr z, HRPrintEnd
;and don't set the adjacent Vertical Attribute if there's no need to & Exit routine
ld a,l
add a,32
ld l,a
ld a,d
adc a,h
ld h,a
ld (hl),e
;set the Attribute address to the line below - and set the adjacent Vertical Attribute
;
;drop through now into adjacent Horizontal Attribute subroutine - all RETs will now Exit the routine completely
;
HRPrintAttribute2: ld a,c
cp 248
jr nc, HRPrintEnd
;check to see if we are at Horizontal character 31 - if so then no need to set adjacent Horizontal Attribute
and 7
jr z, HRPrintEnd
;and don't set the adjacent Horizontal Attribute if there's no need to
inc l
ld (hl),e
dec l
;increment the Attribute address - set the adjacent horizontal Attribute - then set the Attribute Address back
;ret
HRPrintEnd:
end asm
END SUB
CLS
DIM x,y as uByte
DIM xd,yd as byte
x=100
y=10
xd=1
yd=1
DO
PAUSE 2
HRPrint(x,y,32,56,0)
HRPrint(x+8,y,32,56,0)
HRPrint(x,y+8,32,56,0)
HRPrint(x+8,y+8,32,56,0)
x=x+xd
y=y+yd
HRPrint(x,y,@gentle,76,0)
HRPrint(x+8,y,@gentle+8,76,1)
HRPrint(x,y+8,@gentle+16,76,0)
HRPrint(x+8,y+8,@gentle+24,76,1)
IF x<=0 OR x>=247 THEN xd=-xd : END IF
IF y<=0 OR y>=184 THEN yd=-yd : END IF
LOOP
end
gentle:
asm
defb 15,15,15,15,15,15,13,15
defb 240,144,208,208,240,240,176,240
defb 15,14,63,0,0,12,26,30
defb 176,112,252,0,0,24,104,120
end asm