blob: a62a050e1225d50496ee53d5b2d8cbcaa508f2a9 [file] [log] [blame]
mov r6, #0x100 @ base memory address
mov r0, #0 @ r0 = low-order word of result
mov r1, #0 @ r1 = high-order word of result
mov r2, #0x69 @ r2<-low-order word of multiplicand
str r2, [r6, #0x10] @ store multiplicand
mov r3, #0x0 @ r3<-high-order word of multiplicand
mov r4, #0x5a @ load multiplier
str r4, [r6, #0x24] @ store multiplicand
mov r5, #0
loop: tst r4, #1 @ is y odd?
addnes r0, r0, r2 @ add and set flags if y is odd
tst r4, #1 @ previous add may have changed flags
adcne r1, r1, r3 @ add and use carry flag if y is odd
lsls r2, r2, #1 @ shift lsw of x left into carry bit
lsl r3, r3, #1 @ make room for the carry bit is msw
adc r3, r3, #0 @ add carry bit to msw of x
lsrs r4, r4, #1 @ shift y right
bne loop @ if y==0, we are done
str r0, [r6, #8] @ store result