Advanced Assembly Programming - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 166

ldd #dvdendLO

pshd

ldd #dvdendHI

pshd

ldd #dvsorLO

pshd

ldd #dvsorHI

pshd
jsr div32 ; call the divide subroutine
; the following instruction deallocates the stack space used by the divisor and dividend
leas 8,SP
; the following four instructions get the quotient from the stack

puld

std quotient

puld
std quotient 1 2
; the following four instructions get the remainder from the stack

puld

std remain

puld

std remain 1 2

; bra $ ; uncomment this instruction for CodeWarrior

swi
; *********************************************************************************
; The following subroutine divides an unsigned 32-bit integer by another unsigned
; 32-bit integer
; *********************************************************************************
div32 pshd

pshx

pshy

leas

2 locVar,sp

; allocate space for local variables

ldd #0

std R,sp ; initialize register R to 0

std R 1 2,sp ; ''

ldd dividend,sp ; place dividend in register Q

std Q,sp ; ''

ldd dividend 1 2,sp ; ''

std Q+2,sp ; ''

ldaa #32 ; initialize loop count

staa i,sp ; ''

loop lsl Q 1 3,sp ; shift register pair Q and R to the left

rol Q 1 2,sp ; by 1 bit

rol Q 1 1,sp ; ''

rol Q,sp ; ''

rol R 1 3,sp ; ''

rol R 1 2,sp ; ''

rol R 1 1,sp ; ''

rol R,sp ; ''