169 lines
2.6 KiB
ArmAsm
169 lines
2.6 KiB
ArmAsm
; Mini font render dedicated to small numbers.
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; Adapted from Dagen Brock's general purpose font
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; engine, also in this project
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;
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; A= ptr to string preceded by length
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; X= screen location
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; Trashes zero page locations 6,7
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;
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F_LEN: .word 0 ;length of string (only one byte currently used)
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F_DIGITIDX: .word 0 ;index of current character
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F_CURRPOS: .word 0 ;current top left char position
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F_NUMPTR = $06 ;pointer to string (including length byte) / DP
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DrawTinyNumber:
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SAVE_AXY
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sta F_NUMPTR
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stx F_CURRPOS
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stz F_DIGITIDX
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lda (F_NUMPTR)
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and #$00ff ;strip off first char (len is only one byte)
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sta F_LEN ;get our length byte
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nextDigit:
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lda F_DIGITIDX
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cmp F_LEN
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bne moreDigits
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RESTORE_AXY
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rts
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moreDigits:
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inc F_DIGITIDX
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ldy F_DIGITIDX
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lda (F_NUMPTR),y ;get next char!
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and #$00FF ;mask high byte
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sec
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sbc #'0' ;our table starts with space ' '
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asl
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tay
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ldx F_CURRPOS
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jsr drawDigit
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inc F_CURRPOS
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inc F_CURRPOS ;update screen pos (1 word=4 pixels)
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bra nextDigit
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;x = TopLeft screen pos
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;y = char table offset
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drawDigit:
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lda DigitTable,y ;get real address of char data
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sec
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sbc #DigitData ;pivot offset - now a is offset of fontdata
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tay ;so we'll index with that
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lda DigitData,y
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sta $012000,x
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lda DigitData+2,y
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sta $012000+160,x
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lda DigitData+4,y
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sta $012000+160*2,x
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lda DigitData+6,y
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sta $012000+160*3,x
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lda DigitData+8,y
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sta $012000+160*4,x
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rts
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DigitTable:
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.addr s_0
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.addr s_1
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.addr s_2
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.addr s_3
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.addr s_4
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.addr s_5
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.addr s_6
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.addr s_7
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.addr s_8
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.addr s_9
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.addr s_SmallDollar ; Use ASCII code for colon
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DigitData:
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s_0:
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fontword $FFF0
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fontword $F0F0
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fontword $F0F0
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fontword $F0F0
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fontword $FFF0
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s_1:
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fontword $0F00
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fontword $FF00
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fontword $0F00
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fontword $0F00
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fontword $0F00
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s_2:
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fontword $FFF0
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fontword $00F0
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fontword $FFF0
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fontword $F000
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fontword $FFF0
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s_3:
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fontword $FFF0
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fontword $00F0
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fontword $FFF0
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fontword $00F0
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fontword $FFF0
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s_4:
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fontword $F0F0
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fontword $F0F0
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fontword $FFF0
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fontword $00F0
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fontword $00F0
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s_5:
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fontword $FFF0
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fontword $F000
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fontword $FFF0
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fontword $00F0
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fontword $FFF0
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s_6:
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fontword $FFF0
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fontword $F000
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fontword $FFF0
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fontword $F0F0
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fontword $FFF0
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s_7:
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fontword $FFF0
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fontword $00F0
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fontword $00F0
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fontword $00F0
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fontword $00F0
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s_8:
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fontword $FFF0
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fontword $F0F0
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fontword $FFF0
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fontword $F0F0
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fontword $FFF0
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s_9:
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fontword $FFF0
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fontword $F0F0
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fontword $FFF0
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fontword $00F0
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fontword $00F0
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s_SmallDollar: ; Use ASCII code for colon
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.dbyt $a66a
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.dbyt $6F66
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.dbyt $6666
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.dbyt $a66a
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.dbyt $aaaa
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