mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-06-29 21:29:32 +00:00
273 lines
3.5 KiB
ArmAsm
273 lines
3.5 KiB
ArmAsm
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;===============================================
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; hgr 7x28 draw sprite, with bg mask in GR $400
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;===============================================
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; SPRITE in INL/INH
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; Location at CURSOR_X CURSOR_Y
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; for now, BG mask is only all or nothing
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; so we just skip drawing if behind
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; left sprite AT INL/INH
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; right sprite at INL/INH + 14
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; left mask at INL/INH + 28
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; right mask at INL/INH + 42
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hgr_draw_sprite_7x28:
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lda #0
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sta MASK_COUNTDOWN
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; set up pointers
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lda INL
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sta h728_smc1+1
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lda INH
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sta h728_smc1+2
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clc
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lda INL
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adc #28
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sta h728_smc3+1
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lda INH
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adc #0
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sta h728_smc3+2
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ldx #0 ; X is row counter
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hgr_7x28_sprite_yloop:
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lda MASK_COUNTDOWN
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and #$3 ; only update every 4th
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bne mask_good
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txa
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pha ; save X
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; recalculate mask
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txa
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clc
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adc CURSOR_Y
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tax
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ldy CURSOR_X
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jsr update_bg_mask
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pla ; restore X
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tax
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mask_good:
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lda MASK
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bne draw_sprite_skip
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txa ; X is current row
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clc
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adc CURSOR_Y ; add in cursor_y
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; calc GBASL/GBASH
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tay ; get output ROW into GBASL/H
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lda hposn_low,Y
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sta GBASL
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lda hposn_high,Y
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sta GBASH
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ldy CURSOR_X
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lda (GBASL),Y ; load background
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h728_smc3:
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and $d000,X ; mask with sprite mask
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h728_smc1:
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ora $d000,X ; or in sprite
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sta (GBASL),Y ; store out
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draw_sprite_skip:
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inc MASK_COUNTDOWN
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inx
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cpx #28
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bne hgr_7x28_sprite_yloop
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rts
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;======================
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; save bg 7x28
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;======================
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save_bg_7x28:
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ldx #0
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save_yloop:
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txa
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pha
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clc
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adc CURSOR_Y
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; calc GBASL/GBASH
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tax
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lda hposn_low,X
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sta GBASL
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lda hposn_high,X
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sta GBASH
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pla
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tax
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ldy CURSOR_X
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lda (GBASL),Y
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sta save_sprite_7x28,X
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inx
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cpx #28
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bne save_yloop
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rts
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;======================
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; restore bg 7x28
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;======================
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restore_bg_7x28:
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ldx #0
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restore_yloop:
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txa ; current row
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clc
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adc CURSOR_Y ; add in y start point
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; calc GBASL/GBASH using lookup table
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tay
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lda hposn_low,Y
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sta GBASL
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lda hposn_high,Y
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sta GBASH
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ldy CURSOR_X
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lda save_sprite_7x28,X
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sta (GBASL),Y
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inx
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cpx #28
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bne restore_yloop
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rts
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;===================
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; update_bg_mask
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;===================
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; newx/7 in Y
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; newy in X
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; updates MASK
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update_bg_mask:
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; calculate peasant priority
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; based on head
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; FIXME: only do this once at beginning
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lda PEASANT_Y
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sec
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sbc #48 ; Y=48
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lsr ; div by 8
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lsr
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lsr
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clc
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adc #2
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sta PEASANT_PRIORITY
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; rrrr rtii top 5 bits row, bit 2 top/bottom
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txa
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and #$04 ; see if odd/even
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beq bg_mask_even
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bg_mask_odd:
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lda #$f0
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bne bg_mask_mask ; bra
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bg_mask_even:
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lda #$0f
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bg_mask_mask:
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sta MASK
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txa
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lsr
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lsr ; need to divide by 8 then * 2
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lsr ; can't just div by 4 as we need to mask bottom bit
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asl
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tax
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lda gr_offsets,X
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sta BASL
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lda gr_offsets+1,X
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sta BASH
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lda (BASL),Y
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ldy MASK
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cpy #$f0
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bne mask_bottom
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mask_top:
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lsr
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lsr
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lsr
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lsr
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jmp mask_mask_mask
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mask_bottom:
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and #$0f
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mask_mask_mask:
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sta MASK
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cmp PEASANT_PRIORITY
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beq mask_false ; branch less than equal
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bcc mask_false ; blt
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mask_true:
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lda #$ff
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sta MASK
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rts
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mask_false:
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lda #$00
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sta MASK
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; priorities
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; 0 = collision
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; 1 = bg = always draw ; Y-48
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; 2 0-55
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; 3 56-63 ; 8/8+2 = 3
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; 4 64-71 ; 16/8+2 = 4
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; 5 72-79
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; 6 80-87 ; 32/8+2 = 6
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; 7 88-95
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; 8 96-103
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; 9 104-111
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; 10 112-119
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; 11 120-127
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; 12 128-135 ; 8
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; 13 136-143
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; 14 144-151
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; 15 152-159
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;====================
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; save area
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;====================
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save_sprite_7x28:
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.byte $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
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.byte $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
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