Arm/pow2

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Write a function that will return whether its parameter is a power of 2. The parameter is an unsigned integer and will not be 0.

int pow2(unsigned int num);

Expected solution length: Around 5 lines.

Sample Input

pow2(4)

Sample Output

r0=1

.global _start
_start:
	ldr r0, =4
	bl pow2
1:	b 1b    // Done

pow2:

Hint...

It is possible to do this without a loop. Consider the binary representations of (2ⁿ) and (2ⁿ-1).

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.global _start _start:

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• arm/odd
• arm/abs
• arm/add
• arm/shiftu
• arm/shifts
• arm/shiftl
• arm/bswap
• arm/popcount ·

arm/pow2

• · arm/mask
• arm/mask2
• arm/zeroext
• arm/signext
• arm/extend
• arm/saturate
• arm/saturate2
• arm/bits1

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