SX Microcontroller Radix Math Method

Binary to BCD half-packed 8 bit to 3 digit

From: Scott Dattalo, notes

Translated and optimized for the Scenix SX by Nikolai Golovchenko

;********************************
;binary_to_bcd - 8-bits
;
;Input
;  bin  - 8-bit binary number
;       A1*16+A0
;Outputs
; hundreds - the hundreds digit of the BCD conversion
; tens_and_ones - the tens and ones digits of the BCD conversion
binary_to_bcd:

        clr     hundreds
        mov     W, <>bin                ;w  = A0*16+A1
        add     W, bin                  ;w  = A0+A1
        and     W, #00001111b           ;w  = A0+A1 % 16

        mov     tens_and_ones, W        ;tens_and_ones = A0+A1 % 16
        mov     W, #$16
        snb     DC                      ;if A0+A1 > 16
        add     tens_and_ones, W        ;  tens_and_ones  += 16
        mov     W, #$06
        snb     DC                      ;if tens_and_ones % 16 > 10
        add     tens_and_ones, W        ;  tens_and_ones  += 6

        add     tens_and_ones, W        ;tens_and_ones  += 6
        sb      DC                      ;if tens_and_ones < 10
        sub     tens_and_ones, W        ;  tens_and_ones  -= 6

        mov     W, #$16 - 1 + $6
        snb     bin.4
        add     tens_and_ones, W
        mov     W, #-$06
        sb      DC
        add     tens_and_ones, W
        mov     W, #$30
        snb     bin.5
        add     tens_and_ones, W

        mov     W, #$20
        snb     bin.7
        add     tens_and_ones, W

        mov     W, #$60
        snb     bin.6
        add     tens_and_ones, W

        add     tens_and_ones, W

        rl      hundreds
        sb      hundreds.0
        sub     tens_and_ones, W

        snb     bin.7
        inc     hundreds

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