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192 lines
3.2 KiB
ArmAsm
192 lines
3.2 KiB
ArmAsm
*
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* Playing with BCD
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*
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* (c) 2018, Brutal Deluxe Software
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*
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xc
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xc
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mx %00
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org $1000
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lst off
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*---
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clc
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xce
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rep #$30
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lda #$1000
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jsr BCD2HEX
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lda #$9999
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jsr BCD2HEX
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lda #$270f
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jsr HEX2BCD
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sec
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xce
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sep #$30
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rts
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*---
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mx %00
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BCD2HEX pha
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* milliers
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and #$f000
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lsr
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lsr
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lsr
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xba
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tax
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lda tblBM,x
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sta result
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* centaines
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lda 1,s
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and #$0f00
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asl
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xba
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tax
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lda tblBC,x
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clc
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adc result
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sta result
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* dizaines
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lda 1,s
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and #$00f0
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lsr
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lsr
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lsr
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tax
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lda tblBD,x
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clc
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adc result
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sta result
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* unites
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lda 1,s
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and #$000f
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asl
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tax
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lda tblBU,x
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clc
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adc result
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sta result
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plx
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jmp printME
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*--- BCD 2 HEX table
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tblBM dw 0000,1000,2000,3000,4000,5000,6000,7000,8000,9000
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tblBC dw 0000,0100,0200,0300,0400,0500,0600,0700,0800,0900
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tblBD dw 0000,0010,0020,0030,0040,0050,0060,0070,0080,0090
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tblBU dw 0000,0001,0002,0003,0004,0005,0006,0007,0008,0009
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*---
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HEX2BCD pha
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* Step 1
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and #$f000
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lsr
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lsr
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lsr
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xba
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tax
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lda tblH1,x
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sta result
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* Step 2
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lda 1,s
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and #$0f00
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asl
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xba
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tax
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sed
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lda tblH2,x
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clc
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adc result
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sta result
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cld
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* Step 3
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lda 1,s
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and #$00f0
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lsr
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lsr
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lsr
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tax
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sed
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lda tblH3,x
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clc
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adc result
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sta result
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cld
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* Step 4
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lda 1,s
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and #$000f
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asl
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tax
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sed
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lda tblH4,x
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clc
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adc result
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sta result
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cld
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exit plx
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jmp printME
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*--- HEX 2 BCD table
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tblH1 dw $0000,$4096,$8192
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tblH2 dw $0000,$0256,$0512,$0768,$1024,$1280,$1536,$1792
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dw $2048,$2304,$2560,$2816,$3072,$3328,$3584,$3840
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tblH3 dw $0000,$0016,$0032,$0048,$0064,$0080,$0096,$0112
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dw $0128,$0144,$0160,$0176,$0192,$0208,$0224,$0240
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tblH4 dw $0000,$0001,$0002,$0003,$0004,$0005,$0006,$0007
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dw $0008,$0009,$0010,$0011,$0012,$0013,$0014,$0015
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*---
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printME sta result
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sec
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xce
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sep #$30
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lda result+1
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jsr $fdda
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lda result
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jsr $fdda
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lda #$8d
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jsr $fded
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clc
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xce
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rep #$30
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rts
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*---
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result ds 2
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