Invert Bit Ranges in Registers | Dataford Interview Questions

An AMD firmware component must update selected bits in a hardware register without changing unrelated control bits. Given a register value, its width, and an inclusive bit range, invert only the bits in that range.

Bit positions are numbered from 0 for the least significant bit to width - 1 for the most significant bit. A bit inversion changes 0 to 1 and 1 to 0.

Formal Specification

Implement invert_bit_range(register, width, left, right).

Input: register, a non-negative integer containing the register value; width, a positive integer; left and right, inclusive bit positions.
Output: The register value after inverting bits from left through right, inclusive.
Bits outside the requested range must remain unchanged.

Constraints

1 <= width <= 64
0 <= register < 2^width
0 <= left <= right < width
The bit range endpoints are inclusive

Function Signature

def invert_bit_range(register, width, left, right):

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