Code: Select all

.section .text
.thumb_func
_start:
 movs r0, #0 
 movs r1, #0 
 adcs r0, r1 @ 1 instead of 0
 movs r0, #0xFFFFFFFF
 movs r1, #1 
 adcs r0, r1 @ 0 instead of 1
 nop

Code: Select all

.section .text
.thumb_func
_start:
 movs r0, #0
 movs r0, #1
 cmp r0, r1 @ This clears carry bit in xpsr.
 mov r0, #0 @ r0 = 0
 mov r1, #0 @ r1 = 0
 adc r0, r1 @ r0 = r0 + r1 + carry(0) = 0
 movs r0, #0xFFFFFFFF @ r0 = max
 movs r1, #1 @ r1 = 1
 adds r0, r1 @ Overflowed, r0 becomes 0 and carry bit is set.
 adc r0, r0 @ r0 = r0 + r0 + carry(1) = 1
 
 nop