Analog-to-Digital Converter - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 618

negb ; compute two's complement of quotient

stab quo

movb #1,sign ; temperature is negative

ldab rem ; if remainder is 0, skip a few instructions

beq convert ;

ldab #62 ; compute 62 2 rem

subb rem ; “

stab rem ; “

bra cal_fract

save_quo stab quo ; save updated quotient

cal_fract ldab rem

beq convert ; come here when positive

ldaa #10 ; compute fractional digit

mul ; “

ldx #62 ; “

idiv ; “

cmpb #31 ; round off fractional digit

blt no_round ; “

inx ; “

cpx #10 ; “

bne no_round ; “

inc quo ; “

bra convert ; prepare to separate integer digits

no_round tfr x,d ; convert fractional digit to ASCII code

addb #$30 ; “

stab fract ; “

convert ldab quo

clra ; “

ldx #10 ; use repeated divide by 10 to separate

idiv ; integral digits

addb #$30 ; “

stab buf 1 2 ; save the one's digit

tfr x,d ; transfer quotient to D

tstb ; is quo zero?

beq add_fra ; if integral part is 0, then add fraction digit

ldx #10 ; separate the ten's digit

idiv

addb #$30 ; convert and store the tens digit

stab buf 1 1 ; “

tfr x,d ; test hundreds digit

tstb ; is quotient 0?

beq add_fra

movb #$31,buf ; hundreds digit, if any, is 1 only

add_fra movb fract,buf 1 4 ; insert fraction digit

ldaa sign ; check the sign

beq out_it

movb #$2D,buf ; when minus, add minus character

out_it ldaa #$C0 ; set cursor to 2nd row

jsr cmd2lcd ; “

ldx #spaces ; clear the 2nd row of the LCD