mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-06-04 03:29:29 +00:00
219 lines
3.6 KiB
ArmAsm
219 lines
3.6 KiB
ArmAsm
; Display a 40x48d lo-res image
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; Uses the 40x48d page1/page2 every-1-scanline pageflip mode
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; by deater (Vince Weaver) <vince@deater.net>
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; Zero Page
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;FRAME = $60
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;BLARGH = $69
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;DRAW_PAGE = $EE
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;LASTKEY = $F1
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;PADDLE_STATUS = $F2
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;TEMP = $FA
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WHICH = $E3
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book:
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lda #0
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sta WHICH
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;===================
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; init screen
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jsr TEXT
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jsr HOME
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bit KEYRESET
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;===================
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; init vars
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lda #0
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sta DRAW_PAGE
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;=============================
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; Load graphic page0
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lda WHICH
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asl
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asl ; which*4
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tay
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lda pictures,Y
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sta GBASL
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lda pictures+1,Y
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sta GBASH
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lda #$c ; load image to $c00
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jsr load_rle_gr
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lda #4
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sta DRAW_PAGE
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jsr gr_copy_to_current ; copy to page1
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; GR part
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bit PAGE1
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bit LORES ; 4
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bit SET_GR ; 4
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bit FULLGR ; 4
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jsr wait_until_keypressed
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;=============================
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; Load graphic page1
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lda WHICH
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asl
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asl ; which*4
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tay
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lda pictures+2,Y
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sta GBASL
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lda pictures+3,Y
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sta GBASH
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lda #$c ; load image to $c00
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jsr load_rle_gr
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lda #0
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sta DRAW_PAGE
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jsr gr_copy_to_current
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; GR part
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bit PAGE0
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jsr wait_until_keypressed
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;==============================
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; setup graphics for vapor lock
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;==============================
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jsr vapor_lock
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; vapor lock returns with us at beginning of hsync in line
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; 114 (7410 cycles), so with 5070 lines to go
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; GR part
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bit LORES ; 4
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bit SET_GR ; 4
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bit FULLGR ; 4
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jsr gr_copy_to_current ; 6+ 9292
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; now we have 322 left
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; 322 - 12 = 310
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; - 3 for jmp
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; 307
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; Try X=9 Y=6 cycles=307
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ldy #6 ; 2
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loopQ: ldx #9 ; 2
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loopR: dex ; 2
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bne loopR ; 2nt/3
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dey ; 2
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bne loopQ ; 2nt/3
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jmp book_loop ; 3
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.align $100
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;================================================
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; Display Loop
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;================================================
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; each scan line 65 cycles
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; 1 cycle each byte (40cycles) + 25 for horizontal
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; Total of 12480 cycles to draw screen
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; Vertical blank = 4550 cycles (70 scan lines)
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; Total of 17030 cycles to get back to where was
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; We want to alternate between page1 and page2 every 65 cycles
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; vblank = 4550 cycles to do scrolling
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; 2 + 48*( (4+2+25*(2+3)) + (4+2+23*(2+3)+4+5)) + 9)
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; 48*[(6+125)-1] + [(6+115+10)-1]
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book_loop:
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ldy #96 ; 2
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book_outer_loop:
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bit PAGE0 ; 4
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ldx #12 ; 65 cycles with PAGE0 ; 2
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book_page0_loop: ; delay 61+bit
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dex ; 2
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bne book_page0_loop ; 2/3
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; bit(4) -1(fallthrough) + loop*5 -1(fallthrouh)+4 extra = 61
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; 5L = 55
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bit PAGE1 ; 4
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ldx #11 ; 65 cycles with PAGE1 ; 2
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;
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book_page1_loop: ; delay 115+(7 loop)+4 (bit)+4(extra)
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dex ; 2
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bne book_page1_loop ; 2/3
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dey ; 2
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bne book_outer_loop ; 2/3
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;======================================================
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; We have 4550 cycles in the vblank, use them wisely
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;======================================================
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; do_nothing should be 4550+1 -2-9 -7= 4533
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jsr book_do_nothing ; 6
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lda KEYPRESS ; 4
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bpl book_no_keypress ; 3
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rts
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book_no_keypress:
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jmp book_loop ; 3
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;=================================
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; do nothing
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;=================================
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; and take 4533-6 = 4527 cycles to do it
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book_do_nothing:
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; Try X=4 Y=174 cycles=4525 R2
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nop ; 2
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ldy #174 ; 2
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bloop1:
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ldx #4 ; 2
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bloop2:
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dex ; 2
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bne bloop2 ; 2nt/3
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dey ; 2
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bne bloop1 ; 2nt/3
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rts ; 6
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pictures:
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.word book_low,book_high
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.include "book_40_48d.inc"
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