193 lines
3.5 KiB
ArmAsm
193 lines
3.5 KiB
ArmAsm
; dsr rotate lores
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; by deater (Vince Weaver) <vince@deater.net>
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; 147 bytes -- original attempt
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; 145 bytes -- hires address tables in zero page
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; 143 bytes -- optimize table init some more
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; 138 bytes -- swap X and Y in lores code
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; 136 bytes -- remove unnecessary compare
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; 135 bytes -- realize with shift, hclr is unneccesary
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; 134 bytes -- optimize Y usage in inner loop
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; 132 bytes -- don't need to init rotate?
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; 135 bytes -- bot jump
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; Zero Page
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GBASL = $26
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GBASH = $27
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COLOR = $30
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HGR_X = $E0
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HGR_Y = $E2
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HGR_COLOR = $E4
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HGR_HORIZ = $E5
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HGR_PAGE = $E6
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HGR_SCALE = $E7
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ROTATION = $FA
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COUNT = $FC
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YY = $FD
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BB = $FE
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XX = $FF
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; Soft Switches
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SET_GR = $C050
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SET_TEXT = $C051
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FULLGR = $C052
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TEXTGR = $C053
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PAGE1 = $C054 ; Page1
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PAGE2 = $C055 ; Page2
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LORES = $C056 ; Enable LORES graphics
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HIRES = $C057 ; Enable HIRES graphics
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; ROM routines
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HGR = $F3E2
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HGR2 = $F3D8
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HCLR = $F3F2
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HPLOT0 = $F457 ; plot at (Y,X), (A)
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WAIT = $FCA8 ; delay 1/2(26+27A+5A^2) us
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HPOSN = $F411 ; (Y,X),(A) (valued stores in HGRX,XH,Y)
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PLOT = $F800 ;; PLOT AT Y,A
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SETCOL = $F864 ;; COLOR=A
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XDRAW0 = $F65D
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hgr_lookup_h = $40 ; $40-$70
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hgr_lookup_l = $70 ; $70-$A0
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;hgr_lookup_h = $1000
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;hgr_lookup_l = $1100
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dsr_rotate:
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;===================
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; init screen
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jsr HGR ; clear PAGE1
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; A,Y are 0?
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bit FULLGR
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;===================
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; init vars
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; sta ROTATION ; start at 0
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; not needed if don't care start?
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ldx #4
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stx HGR_SCALE
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;===================
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; int tables
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ldx #47
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init_loop:
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txa
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jsr HPOSN ; important part is A=ycoord
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ldx HGR_Y ; A value stored in HGR_Y
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lda GBASL
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sta hgr_lookup_l,X
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lda GBASH
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sta hgr_lookup_h,X
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dex
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bpl init_loop
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bit LORES
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big_loop:
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;=====================================
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; draw dsr
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draw_dsr:
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ldy #0 ; Y 0 here from HCLR
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ldx #15
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lda #20
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jsr HPOSN ; set screen position to X= (y,x) Y=(a)
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; saves X,Y,A to zero page
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; after Y= orig X/7
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; A and X are ??
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ldx #<shape_dsr ; point to bottom byte of shape address
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ldy #>shape_dsr ; point to top byte of shape address
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; ROT in A
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lda ROTATION ; ROT=0
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jsr XDRAW0 ; XDRAW 1 AT X,Y
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; Both A and X are 0 at exit
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; Z flag set on exit
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;===============================
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; copy to lores
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; X654 3210 X654 3210
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ldy #47
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sty YY ; set y-coord to 47
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lsier_outer:
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ldx YY ; a bit of a wash
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lda hgr_lookup_l,X
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sta hgr_scrn_smc+1
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lda hgr_lookup_h,X
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sta hgr_scrn_smc+2
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ldx #0
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ldy #0 ; COUNT
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lsier_inner:
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lda #6
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sta BB
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lsier_inner_inner:
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hgr_scrn_smc:
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lsr $2000,X ; note this also clears screen
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lda #0
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bcs no_color
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lda YY ; get Y-coord into A
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no_color:
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jsr SETCOL
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lda YY ; y-coord in A
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; x-coord already in Y
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jsr PLOT ; plot at Y,A
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iny ; increment count
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cpy #40 ; if hit 40, done
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beq done_line
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dec BB ; decrement byte count
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bpl lsier_inner_inner ; if <7 then keep shifting
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inx ; increment hires-x value
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bne lsier_inner ; bra
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done_line:
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dec YY ; decrement y-coord
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bpl lsier_outer ; until less than 0
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end:
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inc ROTATION
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inc ROTATION
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jmp big_loop
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shape_dsr:
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.byte $2d,$36,$ff,$3f
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.byte $24,$ad,$22,$24,$94,$21,$2c,$4d
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.byte $91,$3f,$36,$00
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; $3F5 - 130 = $373
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for_bot:
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jmp dsr_rotate
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