mirror of
https://frontier.innolan.net/github/AmigaExamples.git
synced 2026-09-12 04:31:46 +00:00
221 lines
5.2 KiB
ArmAsm
221 lines
5.2 KiB
ArmAsm
include "includes.i"
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xdef DrawText8
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xdef font
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BLIT_LF_MINTERM equ $ca ; cookie cut
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BLIT_WIDTH_WORDS equ 2 ; blit 2 words to allow shifting
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BLIT_WIDTH_BYTES equ 4
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FONT_HEIGHT equ 8
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FONT_WIDTH equ 8
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FONTMAP_WIDTH_BYTES equ 32
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_SCREEN_BIT_DEPTH equ 4
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_BITPLANE_WIDTH_BYTES equ 320/8
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DrawText8:
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;; a0 - bitplane
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;; a1 - text
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;; d0 - xpos
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;; d1 - ypos
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movem.l d0-d3/a1-a2,-(sp)
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WaitBlitter
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;; blitter config that is shared for every character
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move.w #BC0F_SRCB|BC0F_SRCC|BC0F_DEST|BLIT_LF_MINTERM,d3 ; BLTCON0 value
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move.w #FONTMAP_WIDTH_BYTES-BLIT_WIDTH_BYTES,BLTBMOD(a6) ; B modulo
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move.w #_BITPLANE_WIDTH_BYTES-BLIT_WIDTH_BYTES,BLTCMOD(a6) ; C modulo
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move.w #_BITPLANE_WIDTH_BYTES-BLIT_WIDTH_BYTES,BLTDMOD(a6) ; D modulo
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move.w #$0000,BLTALWM(a6) ; mask out extra word used for shifting
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move.w #$ffff,BLTADAT(a6) ; preload source mask so only BLTA?WM mask is used
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move.l #font,a5 ; font pointer
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move.l a0,a2 ; bitplane pointer
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mulu.w #_BITPLANE_WIDTH_BYTES*_SCREEN_BIT_DEPTH,d1 ; d1 = ypos bytes
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adda.w d1,a2 ; dest += YPOS_BYTES
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move.w d0,d1 ; xpos
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lsr.w #3,d1 ; d2 = xpos bytes
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adda.w d1,a2 ; dest += XPOS_BYTES
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.loop:
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moveq #0,d1
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move.b (a1)+,d1 ; get next character
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cmp.b #0,d1 ; 0 terminates the string
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beq .done ; finished!
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lsl.w #2,d1 ; font atlas index = char * 4
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move.l d0,d2 ; xpos
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WaitBlitter
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btst #2,d1 ; check if odd or even char
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beq .evenChar ;
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.oddChar
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subq #8,d2 ; offset the x position for the odd character
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move.w #$00FF,BLTAFWM(a6) ; select the second (odd) character in the word
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subq #1,a2 ; move the destination pointer left by one byte
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move.l a2,BLTCPTH(a6) ; background top left corner
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move.l a2,BLTDPTH(a6) ; destination top left corner
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addq #1,a2
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bra .continue
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.evenChar:
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move.w #$FF00,BLTAFWM(a6) ; select the first character in the word
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move.l a2,BLTCPTH(a6) ; background top left corner
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move.l a2,BLTDPTH(a6) ; destination top left corner
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.continue:
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;; this shift will give us the bits to shift (bits 0-3) in bits (12-15) of d2
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swap d2 ; d2 << 12
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lsr.l #4,d2 ;
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move.w d2,BLTCON1(A6) ; set the shift bits 12-15, bits 00-11 cleared
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move.l fontAtlas(pc,d1.w),BLTBPTH(a6) ; source bitplane
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or.w d3,d2 ; d2 = BLTCON0 value
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move.w d2,BLTCON0(a6) ; set minterm, dma channel and shift
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move.w #(FONT_HEIGHT*_SCREEN_BIT_DEPTH)<<6|(BLIT_WIDTH_WORDS),BLTSIZE(a6) ;rectangle size, starts blit
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add.l #FONT_WIDTH,d0 ; increment the x position
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addq #1,a2 ; increment the dest buffer pointer
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bra .loop
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.done:
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movem.l (sp)+,d0-d3/a1-a2
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rts
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CharAddress: macro
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dc.l font+(((\1)/FONTMAP_WIDTH_BYTES)*(FONT_HEIGHT*FONTMAP_WIDTH_BYTES*_SCREEN_BIT_DEPTH))+((\1)-(((\1)/FONTMAP_WIDTH_BYTES)*FONTMAP_WIDTH_BYTES))
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endm
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fontAtlas:
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CharAddress 0
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CharAddress 1
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CharAddress 2
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CharAddress 3
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CharAddress 4
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CharAddress 5
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CharAddress 6
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CharAddress 7
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CharAddress 8
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CharAddress 9
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CharAddress 10
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CharAddress 11
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CharAddress 12
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CharAddress 13
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CharAddress 14
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CharAddress 15
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CharAddress 16
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CharAddress 17
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CharAddress 18
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CharAddress 19
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CharAddress 20
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CharAddress 21
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CharAddress 22
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CharAddress 23
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CharAddress 24
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CharAddress 25
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CharAddress 26
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CharAddress 27
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CharAddress 28
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CharAddress 29
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CharAddress 30
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CharAddress 31
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CharAddress 32
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CharAddress 33
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CharAddress 34
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CharAddress 35
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CharAddress 36
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CharAddress 37
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CharAddress 38
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CharAddress 39
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CharAddress 40
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CharAddress 41
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CharAddress 42
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CharAddress 43
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CharAddress 44
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CharAddress 45
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CharAddress 46
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CharAddress 47
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CharAddress 48
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CharAddress 49
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CharAddress 50
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CharAddress 51
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CharAddress 52
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CharAddress 53
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CharAddress 54
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CharAddress 55
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CharAddress 56
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CharAddress 57
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CharAddress 58
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CharAddress 59
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CharAddress 60
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CharAddress 61
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CharAddress 62
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CharAddress 63
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CharAddress 64
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CharAddress 65
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CharAddress 66
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CharAddress 67
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CharAddress 68
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CharAddress 69
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CharAddress 70
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CharAddress 71
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CharAddress 72
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CharAddress 73
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CharAddress 74
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CharAddress 75
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CharAddress 76
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CharAddress 77
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CharAddress 78
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CharAddress 79
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CharAddress 80
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CharAddress 81
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CharAddress 82
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CharAddress 83
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CharAddress 84
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CharAddress 85
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CharAddress 86
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CharAddress 87
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CharAddress 88
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CharAddress 89
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CharAddress 90
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CharAddress 91
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CharAddress 92
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CharAddress 93
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CharAddress 94
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CharAddress 95
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CharAddress 96
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CharAddress 97
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CharAddress 98
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CharAddress 99
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CharAddress 100
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CharAddress 101
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CharAddress 102
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CharAddress 103
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CharAddress 104
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CharAddress 105
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CharAddress 106
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CharAddress 107
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CharAddress 108
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CharAddress 109
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CharAddress 110
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CharAddress 111
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CharAddress 112
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CharAddress 113
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CharAddress 114
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CharAddress 115
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CharAddress 116
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CharAddress 117
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CharAddress 118
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CharAddress 119
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CharAddress 120
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CharAddress 121
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CharAddress 122
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CharAddress 123
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CharAddress 124
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CharAddress 125
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CharAddress 126
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CharAddress 127
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font:
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incbin "out/font8x8.bin"
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