====== 32 bit hexadecimal to decimal conversion ======
By Graham.
In cases you need to print decimal values, you can use this routine to convert any unsigned 32 bit value to decimal. It doesn't use the BCD mode. The conversion is done by repeatedly dividing the 32 bit value by 10 and storing the remainder of each division as decimal digits.
; prints a 32 bit value to the screen
printdec
jsr hex2dec
ldx #9
l1 lda result,x
bne l2
dex ; skip leading zeros
bne l1
l2 lda result,x
ora #$30
jsr $ffd2
dex
bpl l2
rts
; converts 10 digits (32 bit values have max. 10 decimal digits)
hex2dec
ldx #0
l3 jsr div10
sta result,x
inx
cpx #10
bne l3
rts
; divides a 32 bit value by 10
; remainder is returned in akku
div10
ldy #32 ; 32 bits
lda #0
clc
l4 rol
cmp #10
bcc skip
sbc #10
skip rol value
rol value+1
rol value+2
rol value+3
dey
bpl l4
rts
value .byte $ff,$ff,$ff,$ff
result .byte 0,0,0,0,0,0,0,0,0,0
16-bit version with tightened up loops and routine structure:
// Converts 16 bit values to 5 decimal digits.
ldx #-5
!Loop:
ldy #16 // Divides a 16 bit value by 10 (Remainder in A)
lda #0
clc
!: rol
cmp #10
bcc !+
sbc #10
!: rol value
rol value+1
dey
bpl !--
sta result-[255-4],x
inx
bne !Loop-
// Print result, skip leading zeros
ldx #4
!: lda result,x
beq !Skip+
ora #$30
jsr $ffd2
!Skip:
dex
bpl !-
rts
value: .word 65535
result: .byte 0,0,0,0,0
NB! If you're only looking to convert, not print; Replace jsr $ffd2 with sta result,x.
NB!! If you want to maintain digit positioning, replacing proceeding zero's with #$20.
NB!!! If you wish to extend to 24, 32 or whatever size, adjust the following values:
ldx #-5 // How many digits as a negative number
ldy #16 // How many bits as a positive number
sta result-[255-4],x // Change the "-4" to the negative quantity of digits-1 (i.e. 24 bit => [255-23]
ldx #4 // How many digits-1 as a positive number
value: .word 65535 // Adjust to quantity of bits needed
result: .byte 0,0,0,0,0 // Adjust to quantity of digits needed
Finally adjust the quantity of "rol value+n" to: roundup(bits/8)