Another attempt to repeat the famous Atari rainbow Logo.
Here I'm trying to use PL65 internal assembler and GRAPHICS library.
At first, we need to draw Atari Fuji, thus we need to convert Polar to Decart and so we need INTEGER algorithm for Square Root calculation.
(Not float. Sic! No one really needs semipicsels!)
Something from Internet:
Let's begin to substruct ALL INCREASING INTEGER ODD NUMBERS, while the result is not negative...
And the quantity of steps will be the square root.
SQRT(32)=5
32-1=31 -> 31-3=28 -> 28-5=23 -> 23-7=16 -> 16-9=7 -> 7-11<0
1 2 3 4 5
The PL65 Code of Sqrt() Function (in MATH.LIB):
! -----------------------------------
! Calculating Square Root from Integer
! On entry INP contains input Integer
! On exit OUT contains SQRT, OUT+1 contains Reminder
FUNC Sqrt(INT INP)
INT OUT
BEGIN
STX XSAVE
LDY #$01; STY OUT; DEY; STY OUT+1
:again
SEC
LDA INP
TAX
SBC OUT STA INP
LDA INP+1 SBC OUT+1 STA INP+1
BCC nomore
INY
LDA OUT ADC #$01 STA OUT
BCC again
INC OUT+1 BNE again
:nomore STY OUT STX OUT+1
LDX XSAVE
END OUT
Really, OUT is a temporary accumulative varyable ...
1 - The hard rule of PL65 is:
Using 6502 X-register in any way without it's previous saving will kill software stack pointer of PL65!!! (and your beloved program...)
THUS: Save X to XSAVE before!!! And restore it from XSAVE after ...
2 - When we ADC 1 with CARRY being previously set we adds CARRY value too!
Thus in fact we adds 2! And our numbers stay odd anyway!
3 - Using ; - sign in assembler part of PL65 prevents compiler from mixing for example assembler ;AND operator with high level PL65 AND statement!
The next assembler part is rainbow effect itself.
The Code!
! =================================
! ALOGO.PRG
! Draws Fuji with Raibow effect
! CopyLEFT (C) 2013 EZsoft
! Uses MATH.LIB & PEEKPOKE.LIB !!!
! =================================
INCLUDE D:MATH.LIB
INCLUDE D:PEEKPOKE.LIB
INCLUDE D:GRAPHICS.LIB
! -----------------------------------
! Draws rectangle Canvas
PROC Canvas(BYTE Col INT X0,X1 BYTE Y0,Y1)
BEGIN
COLOR=Col
PLOT(X0,Y1) DRAW(X1,Y1) DRAW(X1,Y0) DRAW(X0,Y0)
POKE(765,3) ! Color of canvas frame
GFILL(X0,Y1)
END
! -----------------------------------
! Draws ATARI Fuji Logo
PROC Fuji(BYTE Col)
BYTE T,B INT R
BEGIN
COLOR=Col T=20 B=76
FOR R=80 TO 84 DO
PLOT(R,T) DRAW(R,B) PLOT(160-R,T) DRAW(160-R,B)
NEXT
FOR R=86 TO 115 DO
IF R>90 THEN T=43+Sqrt(626-(116-R)*(116-R)) ENDIF
B=45+Sqrt(962-(116-R)*(116-R))
PLOT(R,T) DRAW(R,B) PLOT(160-R,T) DRAW(160-R,B)
NEXT
END
! -----------------------------------
! The famous Atari Rainbow effect
PROC Rainbow()
BEGIN
REPEAT
LDA $D200 ! POT0
ADC $14 ! RTCLOK+2
STA $D017 ! COLPF1
LDA $D40B ! VCOUNT
SBC $14 ! RTCLOK+2
STA $D01A ! COLBK
STA $D40A ! WSYNC
UNTIL (PEEK(764)=28)
END
! -----------------------------------
! Main program
MAIN()
BYTE Col INT X0,X1 BYTE Y0,Y1
BEGIN
GRAPHICS(7+16)
POKE(708,28) POKE(709,52) POKE(710,0) POKE(712,148)
Col=1 X0=35 X1=125 Y0=12 Y1=85
Canvas(Col,X0,X1,Y0,Y1)
Col=2
Fuji(Col)
Rainbow()
END
It works!
Here I'm trying to use PL65 internal assembler and GRAPHICS library.
At first, we need to draw Atari Fuji, thus we need to convert Polar to Decart and so we need INTEGER algorithm for Square Root calculation.
(Not float. Sic! No one really needs semipicsels!)
Something from Internet:
Let's begin to substruct ALL INCREASING INTEGER ODD NUMBERS, while the result is not negative...
And the quantity of steps will be the square root.
SQRT(32)=5
32-1=31 -> 31-3=28 -> 28-5=23 -> 23-7=16 -> 16-9=7 -> 7-11<0
1 2 3 4 5
The PL65 Code of Sqrt() Function (in MATH.LIB):
! -----------------------------------
! Calculating Square Root from Integer
! On entry INP contains input Integer
! On exit OUT contains SQRT, OUT+1 contains Reminder
FUNC Sqrt(INT INP)
INT OUT
BEGIN
STX XSAVE
LDY #$01; STY OUT; DEY; STY OUT+1
:again
SEC
LDA INP
TAX
SBC OUT STA INP
LDA INP+1 SBC OUT+1 STA INP+1
BCC nomore
INY
LDA OUT ADC #$01 STA OUT
BCC again
INC OUT+1 BNE again
:nomore STY OUT STX OUT+1
LDX XSAVE
END OUT
Really, OUT is a temporary accumulative varyable ...
1 - The hard rule of PL65 is:
Using 6502 X-register in any way without it's previous saving will kill software stack pointer of PL65!!! (and your beloved program...)
THUS: Save X to XSAVE before!!! And restore it from XSAVE after ...
2 - When we ADC 1 with CARRY being previously set we adds CARRY value too!
Thus in fact we adds 2! And our numbers stay odd anyway!
3 - Using ; - sign in assembler part of PL65 prevents compiler from mixing for example assembler ;AND operator with high level PL65 AND statement!
The next assembler part is rainbow effect itself.
The Code!
! =================================
! ALOGO.PRG
! Draws Fuji with Raibow effect
! CopyLEFT (C) 2013 EZsoft
! Uses MATH.LIB & PEEKPOKE.LIB !!!
! =================================
INCLUDE D:MATH.LIB
INCLUDE D:PEEKPOKE.LIB
INCLUDE D:GRAPHICS.LIB
! -----------------------------------
! Draws rectangle Canvas
PROC Canvas(BYTE Col INT X0,X1 BYTE Y0,Y1)
BEGIN
COLOR=Col
PLOT(X0,Y1) DRAW(X1,Y1) DRAW(X1,Y0) DRAW(X0,Y0)
POKE(765,3) ! Color of canvas frame
GFILL(X0,Y1)
END
! -----------------------------------
! Draws ATARI Fuji Logo
PROC Fuji(BYTE Col)
BYTE T,B INT R
BEGIN
COLOR=Col T=20 B=76
FOR R=80 TO 84 DO
PLOT(R,T) DRAW(R,B) PLOT(160-R,T) DRAW(160-R,B)
NEXT
FOR R=86 TO 115 DO
IF R>90 THEN T=43+Sqrt(626-(116-R)*(116-R)) ENDIF
B=45+Sqrt(962-(116-R)*(116-R))
PLOT(R,T) DRAW(R,B) PLOT(160-R,T) DRAW(160-R,B)
NEXT
END
! -----------------------------------
! The famous Atari Rainbow effect
PROC Rainbow()
BEGIN
REPEAT
LDA $D200 ! POT0
ADC $14 ! RTCLOK+2
STA $D017 ! COLPF1
LDA $D40B ! VCOUNT
SBC $14 ! RTCLOK+2
STA $D01A ! COLBK
STA $D40A ! WSYNC
UNTIL (PEEK(764)=28)
END
! -----------------------------------
! Main program
MAIN()
BYTE Col INT X0,X1 BYTE Y0,Y1
BEGIN
GRAPHICS(7+16)
POKE(708,28) POKE(709,52) POKE(710,0) POKE(712,148)
Col=1 X0=35 X1=125 Y0=12 Y1=85
Canvas(Col,X0,X1,Y0,Y1)
Col=2
Fuji(Col)
Rainbow()
END
It works!
