mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-06-26 00:29:29 +00:00
299 lines
3.9 KiB
ArmAsm
299 lines
3.9 KiB
ArmAsm
; random scroll bot
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; 162 bytes -- working code
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; 158 bytes -- play with bitmap
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; 156 bytes -- use HGR2 to init screen (and A)
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; 155 bytes -- remove use of LINE count
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; 155 bytes -- use ZP for output
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; 153 bytes -- count X backwards
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; 150 bytes -- use $28 to center Y trick
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; 146 bytes -- inline update scroll, makes it scroll right rather than up
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; 144 bytes -- share common sta OUTH
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; 141 bytes -- more wrapping loop stuff
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; ***** *****
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; ***** *****
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; ** ** @@ @@@@@@
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; ** ** @@ @@
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; ** ** @@@@@@ @@@@@@ @@@@@@
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; ***** ***** @@ @@ @@ @@
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; ***** ***** @@@@@@ @@@@@@ @@
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; by Vince `deater` Weaver
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FULLGR = $C052
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PAGE1 = $C054
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PAGE2 = $C055
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LORES = $C056 ; Enable LORES graphics
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HGR2 = $F3D8
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PLOT = $F800 ; PLOT AT Y,A (A colors output, Y preserved)
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GBASCALC = $F847 ; Y in A, put addr in GBASL/GBASH
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SETGR = $FB40
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WAIT = $FCA8 ; delay 1/2(26+27A+5A^2) us
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GBASL = $26
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GBASH = $27
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OUTL = $FC
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OUTH = $FD
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PAGE = $FE
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LINE = $FF
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pattern1 = $f000 ; location in memory
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random:
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jsr HGR2 ; set HIRES, FULLSCREEN
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bit LORES ; set LORES
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; A is 0 from HGR2
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sta OUTL
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; lda #$4
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main_loop:
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sta PAGE ; start at page 1
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asl ; make OUTH $4 or $8 depending on value in PAGE
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; which we have in A above or at end of loop
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asl ; C is 0
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adc #4
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sta OUTH
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lda #200
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jsr WAIT
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;============================
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; draw an interleaved line
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line_loop:
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ldy #119
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screen_loop:
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tya ; extrapolate Y from X
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and #$7
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tax
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pattern_smc:
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lda pattern1,X
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inner_loop_smc:
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sta (OUTL),Y
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dey
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bpl screen_loop
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;=================================
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; move to next pattern
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; jsr scroll_pattern
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scroll_pattern:
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clc
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lda pattern_smc+1
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adc #8
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and #$1f
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sta pattern_smc+1
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; rts
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; move to next line
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clc
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lda OUTL
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adc #$80
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sta OUTL
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bcc line_loop
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; A is $00 if we get here
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adc OUTH
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sta OUTH
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and #$3
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bne line_loop
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done_bg:
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;=======================================
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; done drawing frame
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;=======================================
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;======================
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; draw bitmap
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ldx #7
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boxloop:
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txa
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jsr GBASCALC ; calc address of X
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; note we center to middle of screen
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; by noting the middle 8 lines
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; are offset by $28 from first 8 lines
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; GBASL is in A at this point
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clc
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adc #12+$28
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sta GBASL ; center x-coord and y-coord at same time
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lda PAGE ; want to add 0 or 4 (not 0 or 1)
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asl
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asl ; this sets C to 0
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adc GBASH
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sta GBASH
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ldy #15
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draw_line_loop:
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lda bitmap2,X ; get low bit of bitmap2 into carry
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lsr
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lda #$00 ; black is default color
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ror bitmap,X ; 16-bit rotate (in memory)
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ror bitmap2,X
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bcc its_black
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lda #$ff
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its_black:
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sta (GBASL),Y ; partway down screen
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dey
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bpl draw_line_loop
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dex
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bpl boxloop
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;=========================
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; scroll one line
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; jsr scroll_pattern
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; to scroll up need to add 8?
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inc pattern_smc+1
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; switch page
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lda PAGE
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tax
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ldy PAGE1,X ; flip page
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eor #$1
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; sta PAGE ; is 0 or 1
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; reset page smc
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; OUTH is either C00 or 800
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; want C00 to go to 400 and 800 to stay the same
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; asl
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; asl ; C is 0
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; adc #4
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; sta OUTH
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; lda #200
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; jsr WAIT
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; A is 0 after
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jmp main_loop ; bra
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.if 0
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scroll_pattern:
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clc
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lda pattern_smc+1
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adc #8
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and #$1f
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sta pattern_smc+1
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rts
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.endif
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;01234567|01234567
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;
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; @@@@ @@@@
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; @@ @@
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; @@ @@
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; @@ @@
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; @@@@ @@@@
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;
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;@@@@@@@@@@@@@@@@
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bitmap:
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.byte $FF ;,$FF
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.byte $E1 ;,$87
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.byte $F9 ;,$9F
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.byte $F9 ;,$9F
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.byte $F9 ;,$9F
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.byte $E1 ;,$87
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.byte $FF ;,$FF
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.byte $00 ;,$00
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bitmap2:
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.byte $FF
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.byte $87
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.byte $9F
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.byte $9F
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.byte $9F
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.byte $87
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.byte $FF
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.byte $00
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; want this at $3F5
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; we are 141 bytes long, so 36b
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jmp random
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.if 0
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;======================
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; draw box
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ldx #16
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boxloop:
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txa
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jsr GBASCALC
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lda PAGE
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asl
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asl
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; clc
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adc GBASH
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sta GBASH
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color_smc:
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lda #$FF ; white bar
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ldy #30
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draw_line_loop:
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sta (GBASL),Y ; partway down screen
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dey
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cpy #10
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bne draw_line_loop
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dex
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cpx #6
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bne boxloop
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.endif
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